Principal Host Research Articles

First report of brown rot of nectarine caused by Monilia yunnanensis in Tibet.

Brown rot caused by Monilinia spp. is one of the most important diseases of stone fruits. To date, three species of Monilinia have been found to occur on Prunus species worldwide: Monilinia fructicola (G. Winter) Honey, Monilinia fructigena (Aderhold & Ruhland) Honey, and Monilinia laxa (Aderhold & Ruhland) Honey (Zhu et al. 2005; Hu et al. 2011a). While M. fructicola is widespread in the Americas, and parts of Europe and Asia (CABI, 2010), M. laxa and M. fructigena are the primary species causing brown rot of peach in Europe (Bryde et al. 1977). In China, a new species Monilia yunnanensis was identified in 2011 (Hu et al. 2011b; Zhao et al. 2013; Yin et al. 2015; Yin et al. 2017). However, the species causing brown rot of nectarine (Prunus persica var. nectarina) in Tibet have not been undertaken. In the summer of 2017-2018, brown rot disease of nectarine was observed in Nyingchi, Tibet, and approximately 30% of nectarines were affected annually. Therefore, the brown rot disease of nectarine is one of the main factors that restrict the yield and quality of nectarine fruit production, and causes severe economic losses in Tibet. Thirty-six nectarine fruit with typical brown rot symptoms were collected from Tibet during the summer of 2017-2018. In order to isolate the causal agent, small pieces of pericarp were disinfected with 75% ethanol for 1 min, and then for 1 min in 1% NaOCl, rinsed in sterile distilled water for three times, dried on sterile paper and placed on potato dextrose agar (PDA). Thirty-six single-spore isolates were obtained and all morphologically similar, and three representative isolates 2-1, 2-16 and 2-31 which were from different period and years in 2017-2018 were characterized phylogenetically and morphologically to identify them to species level. Pathogenicity of each representative isolate was confirmed by inoculating five surface-disinfected mature nectarines with mycelial plugs in the wound of the fruit. Nectarine fruit inoculated with sterile PDA plugs served as the negative control. The inoculated nectarines developed brown lesions after 6 days incubation at 22°C, and the pathogen was successfully re-isolated. There were no symptoms on the control nectarine fruit. The isolates 2-1, 2-16 and 2-31 produced gray-green colonies with even margins and concentric rings of sporogenous mycelium after 3 days incubation, and abundant black-colored stromata on the media after 16 days of incubation at 22°C, resembling those described for M. yunnanensis (Hu et al. 2011b). Conidia were one-celled, hyaline, ellipsoid to lemon shape (9.24 to 15.58 μm), and borne in branched monilioid chains. The average daily growth of mycelium on PDA at 22°C was 11.56 mm. Therefore, the isolates 2-1, 2-16 and 2-31 were preliminarily identified as M. yunnanensis based on the morphological investigations (Hu et al. 2011b). Morphological identification was confirmed by phylogenetic analysis based on sequences of glyceraldehyde-3-phosphate dehydrogenase (G3PDH) and β-tubulin (TUB2) genes of 2-1, 2-16 and 2-31 which were amplified using primers Mon-G3pdhF/Mon-G3pdhR and Mon-TubF1/Mon-TubR1 (Hu et al. 2011b). In both G3PDH and TUB2 phylogenetic trees, the isolates 2-1, 2-16 and 2-31 formed monophyletic clades within a derived clade with the M. yunnanensis isolates. Additionally, the three isolates were more closely related to M. yunnanensis (HQ908782.1 and HQ908783.1) than to other Monilinia species. Based on morphological and molecular identification, the isolates 2-1, 2-16 and 2-31 were identified as M. yunnanensis. Previously, M. yunnanensis has been reported as a new species causing brown rot of peach in China (Hu et al, 2011b). To our knowledge, this is the first report of M. yunnanensis causing nectarine fruit brown rot in Tibet. These findings suggest that M. yunnanensis is spreading on its principal host plants and causing substantial economic losses in the Tibet fruit production.

Higher mortality of the less suitable brown trout host compared to the principal Atlantic salmon host when infested with freshwater pearl mussel (Margaritifera margaritifera) glochidia

The freshwater pearl mussel (Margaritifera margaritifera) is a highly host-specific parasite, with an obligate parasitic stage on salmonid fish. Atlantic salmon (Salmo salar) and brown trout (Salmo trutta f. trutta and Salmo trutta f. fario) are the only hosts in their European distribution. Some M. margaritifera populations exclusively infest either Atlantic salmon or brown trout, while others infest both hosts with one salmonid species typically being the principal host and the other a less suitable host. Glochidial abundance, prevalence and growth are often used as parameters to measure host suitability, with the most suitable host species displaying the highest parameters. However, it is not known if the degree of host specialisation will negatively influence host fitness (virulence) among different host species. In this study we examined the hypothesis that glochidial infestation would result in differential virulence in two salmonid host species and that lower virulence would be observed on the most suitable host. Atlantic salmon and brown trout were infested with glochidia from two M. margaritifera populations that use Atlantic salmon as their principal host, and the difference in host mortality among infested and control (sham infested) fish was examined. Higher mortality was observed in infested brown trout (the less suitable host) groups, compared to the other test groups. Genetic assignment was used to identify offspring from individual mother mussels. We found that glochidia from individual mothers can infest both the salmonid hosts; however, some mothers displayed a bias towards either salmon or trout. We believe that the differences in host-dependent virulence and the host bias displayed by individual mothers were a result of genotype × genotype interactions between the glochidia and their hosts, indicating that there is an underlying genetic component for this parasite-host interaction.

Enhanced Glycolysis Is Required for Antileishmanial Functions of Neutrophils Upon Infection With Leishmania donovani.

Visceral leishmaniasis (VL) is a fatal parasitic disease if untreated. Treatment options of VL diminish due to emerging drug resistance. Although the principal host cells for the multiplication of Leishmania are macrophages, neutrophils are the first cells infected with the parasites rapidly after parasite inoculation. Leishmania can survive in neutrophils despite the potent antimicrobial effector functions of neutrophils that can eliminate the parasites. Recently, the growing field of immunometabolism provided strong evidence for the therapeutic potential in targeting metabolic processes as a means of controlling immune effector functions. Therefore, the understanding of the immunometabolic profile of neutrophils during Leishmania infection could provide new promising targets for host-directed therapies against VL. To our knowledge, this is the first study addressing the bioenergetics profile of L. donovani-infected primary human neutrophils. Transcriptome analysis of L. donovani-infected neutrophils revealed an early significant upregulation of several glycolytic enzymes. Extracellular flux analysis showed that glycolysis and glycolytic capacity were upregulated in L. donovani-infected neutrophils at 6 h post infection. An increased glucose uptake and accumulation of glycolytic end products were further signs for an elevated glycolytic metabolism in L. donovani-infected neutrophils. At the same time point, oxidative phosphorylation provided NADPH for the oxidative burst but did not contribute to ATP production. Inhibition of glycolysis with 2-DG significantly reduced the survival of L. donovani promastigotes in neutrophils and in culture. However, this reduction was due to a direct antileishmanial effect of 2-DG and not a consequence of enhanced antileishmanial activity of neutrophils. To further address the impact of glucose metabolism during the first days of infection in vivo, we treated C57BL/6 mice with 2-DG prior to infection with L. donovani and assessed the parasite load one day and seven days post infection. Our results show, that seven days post-infection the parasite load of 2-DG treated animals was significantly higher than in mock treated animals. This data indicates that glycolysis serves as major energy source for antimicrobial effector functions against L. donovani. Inhibition of glycolysis abrogates important neutrophil effector functions that are necessary the initial control of Leishmania infection.

Taxonomic revision of Blumeria based on multi-gene DNA sequences, host preferences and morphology.

A taxonomic revision of the hitherto monotypic genus Blumeria was conducted incorporating multi-gene sequence analyses, host preference data and morphological criteria. The sequenced loci included rDNA ITS, partial chitin synthase gene (CHS1), as well as fragments of two unnamed orthologous genes (Bgt-1929, Bgt-4572). The combined evidence led to a reassessment and a new neotypification of B. graminiss. str. (emend.), and the description of seven additional species, viz. B. americana sp. nov. (mainly on hosts of the Triticeae), B. avenae sp. nov. (on Avena spp.), B. bromi-cathartici sp. nov. (on Bromus catharticus), B. bulbigera comb. nov. (on Bromus spp.), B. dactylidis sp. nov. (on Dactylis glomerata as the main host, but also on various other hosts), B. graminicola sp. nov. (on Poa spp. as principal hosts, but also on various other hosts), and B. hordei sp. nov. (on Hordeum spp.). Synonyms were assessed, some were lectotypified, and questionable names previously associated with powdery mildew on monocots were discussed although their identities remained unresolved. Keys to the described species were developed.

Halogen Bearing Amphiboles, Aqueous Fluids, and Melts in Subduction Zones: Insights on Halogen Cycle From Electrical Conductivity

AbstractAmphiboles are hydrous minerals that are formed in the oceanic crust via hydrothermal alteration. The partial substitution of halogens for OH− makes amphibole one of the principal hosts of Cl and F in the subducting slab. In this study, we investigated the electrical conductivity of a suite of halogen bearing amphibole minerals at 1.5 GPa up to 1,400 K. The discontinuous electrical behavior indicates dehydration of amphibole at ∼915 K. This is followed by dehydration induced hydrous melting at temperatures above 1,070 K. We find that the released aqueous fluids have an electrical conductivity of ∼0.1 S/m. This high electrical conductivity is likely to explain anomalously high electrical conductivity observed in certain subduction zone settings. This high electrical conductivity of an order of magnitude greater than the electrical conductivity of pure aqueous fluids at similar conditions is likely due to the partitioning of the F and Cl into the aqueous fluids. We also noted that subsequent to the dehydration, secondary phases form due to the breakdown of the primary halogen bearing amphibole. Chemical analyses of these secondary phases indicate that they are repositories of F and Cl. Hence, we infer that upon dehydration of the primary halogen bearing amphibole, first the F and Cl are partitioned into the aqueous fluids and then the halogens are partitioned back to the secondary mineral phases. These secondary minerals are likely to transport the halogen to the deep Earth and may in part explain the halogen concentration observed in ocean island basalt.

Atopic endotypes as a modulating factor for SARS-CoV-2 infection: mechanisms and implications.

Asthma patients are typically at increased risk for severe outcomes from viral respiratory infections. However, asthma and atopy do not appear to be overrepresented comorbidities in COVID-19 patients, and hypotheses attempt to explain this observation. As COVID-19 continues to spread globally, it is imperative to understand how disease outcomes may be influenced in this population to guide patient care. Angiotensin converting enzyme 2 (ACE2) is the principal host cell receptor for SARS-CoV-2 entry and Transmembrane Protease Serine 2 (TMRSS2) is the main priming protease. Models have linked atopic endotypes to reductions in ACE2 and increases in TMRSS2 on respiratory epithelia. Epidemiologic and experimental findings imply alterations in ACE2 expression correlate with clinical COVID-19 disease, but limitations restrict the ability to draw direct conclusions. There is reasonable evidence to assert atopic endotypes modulate COVID-19 susceptibility, but it remains premature to classify this association as protective or deleterious. Asthma is a heterogeneous disease and epidemiologic studies should focus on investigating COVID-19 outcomes by underlying endotype. Direct experimental and clinical evidence is needed to draw definitive conclusions on how the complex interplay of ACE2 and TMRSS2 affect viral entry. https://www.dropbox.com/sh/9sfwqhz2h78sio3/AAB0JYd4MFzM5JjDFcYwz4CXa?dl=0.

Colonization of a novel host by fleas: changes in egg production and egg size

We studied the success of fleas, Synosternus cleopatrae and Xenopsylla ramesis, in switching to a novel host by establishing experimental lines maintained on different hosts for 18 generations. Fleas fed on principal (P-line) or novel hosts, either sympatric with (S-line) or allopatric to (A-line) a flea and its principal host, then we assessed their reproductive performance via the number and size of eggs. We compared reproductive performance between hosts within a line and between lines within a host asking: (a) whether fleas adapt to a novel host species after multiple generations; (b) if yes, whether the pattern of adaptation differs between novel host species sympatric with or allopatric to a flea and its principal host; and (c) adaptation to a novel host is accompanied with a loss of success in exploitation of an original host. Fleas from the S- and A-lines increased their egg production on a novel host (except X. ramesis from the S-line). S. cleopatrae from the S-line but not the A-line increased egg size on a novel host, whereas X. ramesis from the A-line but not the S-line produced larger eggs from a novel host. We found no indication of a loss of reproductive performance on the original host while adapting to a novel host. We conclude that fleas are able to switch rapidly to a new host with the pattern of a switch to either sympatric or an allopatric host depending on the identities of both flea and host species.

Impact of long-term fertilizer and summer warming treatments on bulk soil and birch rhizosphere microbial communities in mesic arctic tundra

ABSTRACT Recent climate warming in the Arctic is enhancing microbial decomposition of soil organic matter, which may result in globally significant greenhouse gas releases to the atmosphere. To better predict future impacts, bacterial and fungal community structures in both the bulk soil and the rhizosphere of Arctic birch, Betula glandulosa, were determined in control, greenhouse summer warming, and annual factorial nitrogen (N) and phosphate (P) addition treatments twelve years after their establishment. DNA sequence analyses at multiple taxonomic levels consistently indicated substantial bulk soil and rhizosphere microbial community differences among the fertilization treatments but no significant greenhouse effects. These results suggest that climate warming will likely increase the activity rates of soil microbial decomposers but without substantially altering the structure of either the bacterial or fungal communities. Differential abundance testing revealed changes in ectomycorrhizal fungal species of the genus Thelephora in both bulk soil and rhizosphere, with increases in their relative abundance in P and N + P amended plots compared with warming and controls. Because birch is the principal low Arctic ectomycorrhizal host, our results suggest that these fungi may promote this shrub’s competitiveness where tundra soil nutrient availability is enhanced by warming or other means, ultimately contributing to arctic vegetation “greening.”

The Nasal Symbiont <i>Staphylococcus Epidermidis</i> Restricts the Transcription of SARS-CoV-2 Entry Factors in Human Nasal Epithelium

Emerging evidence indicates that severe acute respiratory syndrome-related coronavirus-2 (SARS-CoV-2) targets the human nasal epithelium via the principal entry factors angiotensin-converting enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2), which are highly expressed in the nasal epithelium. However, little is known about suppressive biologics against SARS-CoV-2 entry factors. Here, we show that the nasal commensal Staphylococcus epidermidis altered the host transcriptional response against SARS-CoV-2 by reducing ACE2 and TMPRSS2 gene expression in concert with an increase in serine protease inhibitors. Our data reveal that ACE2 was more abundantly expressed in nasal epithelial (NHNE) cells than bronchial epithelial cells, and inoculation with S. epidermidis reduced ACE2 transcription in NHNE cells. TMPRSS2 mRNA was significantly decreased in NHNE cells and S. epidermidis colony number in human nasal mucus was inversely correlated with ACE2 and TMPRSS2 gene expression in nasal mucosa. In addition, levels of the serine protease inhibitors SERPINE1 and SERPINE2 were significantly increased by S. epidermidis , and this accompanied reduction of TMPRSS2 transcription in nasal epithelial cells. These results characterize the S. epidermidis -regulated host transcriptional response restricting SARS-CoV-2 entry to the nasal epithelium via downregulation of cellular receptors and principal host protease of SARS-CoV-2 coupled with SERPINE1 and SERPINE2 induction.Funding: This work was supported by the Basic Science Research Program through the National Research Foundation of Korea funded by the Ministry of Education (2016R1D1A1B01014116 and 2019M3C9A6091945 to HJK). This research was also supported by a grant from the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare of the Republic of Korea (HI20C0546 to HJK).Declaration of Interest: The authors declare that the research was conducted in the absence of anycommercial or financial relationships that could be construed as potential conflicts ofinterest.Ethical Approval: Participation was voluntary, with written informed consent obtained from all subjects.This study was approved by the Institutional Review Board (IRB) of the SeoulNational University College of Medicine (no. 1709-049-883).

Towards Crossfire Distributed Denial of Service Attack Protection Using Intent-Based Moving Target Defense Over Software-Defined Networking

Crossfire is an indirect target area link-flooding Distributed Denial of Service (DDoS) attack determined to affect the neighbors of the real target. Currently, Crossfire DDoS attacks are acquiring impetus because of their indistinguishability and undetectability. SDN (Software Defined Networking) is a progressing technique because of its adaptability and programmability. Moving Target Defense (MTD) is an arising security strategy to counter attacks by progressively changing the attacked plane. IBN (Intent-based Networking) is another promising methodology for providing dynamic network management. IBN-based MTD can provide efficient MTD solutions because of the concentrated control and observing capacities of the intents when translated into rules inside the SDN control plane. In this paper, a framework for the security of Crossfire DDoS attacks is proposed by making use of Intent-based Traffic modifications through the Open Networking Operating System (ONOS) Rest API and Domain Name System (DNS) port redirection. In this paper, we exploited Intent-based MTD to divert traffic from the principal host to virtual shadow hosts to counter this attack. Traffic redirection helps in masquerading the attacker headed for shadow host and consequently getting the erroneous path towards the network and, hence, the Crossfire attack couldn’t be executed as expected. The proposed technique is simulated using Mininet and ONOS SDN controllers. The outcomes showed traffic is successfully redirected at a low computational expense. Therefore, Crossfire DDoS is efficiently mitigated as promising results are found.

English

Smallholder dairy cattle rumen microbiotas are subjected to a wide range of antimicrobials as well as sudden fluctuations in diets. As such, they develop an enormous reservoir of resistant genes, mobilome and stress response genes. However, information on metagenomic reactions to such dietary variations, especially for cattle reared in the tropics, remains largely unexplored. This meta-analysis was conducted to assess if antibiotic and toxic compound resistance genes (ARGs), stress response genes and bacterial phages, prophages and transposable element genes were present, and to what extent, in three dairy cattle genotypes (Friesian, FriesianXJersey crossbreed, Jersey) reared in a farm that practiced judicious use of antimicrobials. Potential bacterial hosts to these genes were also explored. The rumen metagenomes generated from Next Generation Sequencing (NGS) technology were analyzed using MG-RAST. According to the results stress reaction, resistance and mobilome genes were present in similar amounts in all the three genotypes. Cobalt-zinc-cadmium resistance, fluoroquinolone resistance, methicillin resistance in Staphylococci and multidrug resistance efflux pumps were the most abundant resistant genes and were spread across 20, 24, 16 and 21 bacterial classes, respectively. Bacteria in charge of phage integration and excision, phages replication and phage packaging were mostly allocated to the phyla Firmicutes, Bacteroides and Proteobacteria. Within the stress response genes, metagenomic assembly-based host-tracking analysis identified the extended heat shock dnaK gene cluster as the most abundant genes, while Bacteroides and Clostridium were the principal bacterial hosts. The results show that even with proper use of antimicrobials, the cattle rumen contained an immense distribution of responses to stress, ARGs and mobilome genes distributed in a vast assemblage of hosts. There is also a high correlation between these three functional groups. Key words: Resistome, metagenome, MG-RAST, Stress genes, mobilome

Ixodes silvanus n. sp. (Acari: Ixodidae), a new member of the subgenus Trichotoixodes Reznik, 1961 from northwestern Argentina

Females, nymphs, and larvae of Ixodes silvanus n. sp. collected from birds and from the vegetation in northwestern Argentina (Yungas Phytogeographic Province) are described herein. The new species belongs to the subgenus Trichotoixodes (Acari: Ixodidae). The female is diagnosed by a combination of the following characters: scutum with setae moderately long and more numerous in central field, fewer and moderately long setae on lateral fields, and inconspicuous setae in anterior field; basis capituli subtriangular dorsally; porose areas large and irregular in shape, lacking distinct margins; auriculae with straight edges diverging posterolaterally and ending with small blunt processes; hypostome narrow and pointed with dental formula 4/4 in the anterior third, then 3/3 and 2/2 near the base; coxae I with two spurs, sub-equal in size, internal slightly slimmer than external. The nymph is diagnosed by notum with numerous and long setae, ventral surface covered by numerous whitish setae, scutum with short scapulae and few and shallow punctations, setae on scutum few, short and irregularly distributed, basis capituli sub-triangular dorsally with posterior margin straight, cornua large and directed postero-laterally, auriculae large and projected laterally, lateral margin of basis capituli above auriculae with a lateral and triangular projection, hypostome pointed with dental formula 3/3 in the anterior third and then 2/2, and coxa I with two short, sub-equal, triangular spurs. The diagnostic characters of the larva are: basis capituli dorsally sub-triangular with lateral angles acute and posterior margin straight, auriculae as large triangular lateral projections, hypostome with apex bluntly pointed and dental formula 3/3 in the anterior third and then 2/2, coxa I with two short, sub-equal, triangular spurs, and pattern of dorsal and ventral body setae. This new species is phylogenetically related to Ixodes brunneus, Ixodes turdus and Ixodes frontalis, and the principal hosts for all its parasitic stages are birds.

Geology of the Yeşilyurt (Malatya) fluorite-gold deposit: an example of low-angle normal fault related mineralization, Eastern Anatolia-Turkey

Yeşilyurt gold mineralization is located within the provincial borders of Malatya and Adıyaman in the East Anatolian Region. This mineralization is one of the gold deposits which correlated with low-angle normal/detachment fault. Low-angle normal fault associated with a tectonic setting which is potential extensional in Paleogene-Neogene (?) term. Marble-recrystallized limestone which belongs to the metamorphic core is the dominant rock (footwall) type in the bottom plate of the fault zone. There are deformed graphitic calc-schists (hanging wall) in the upper plate of the fault zone. The fault zone is characterized by fault gauge, cataclasite, and breccia. While the cataclasite, and breccia are the principal ore host, there is weaker mineralization in fault gauge. Alteration assemblages are: (1) silica replacements/veinlets and, (2) quartz-pyrite replacements / veinlets. High gold contents are closely related to silicification and quartz-pyrite alteration which damaged the primary textures. Small volume syn-tectonic magmatic rocks are simultaneous and typically monitored in the silicified areas which are border on the high-grade gold mineralization. Mineralization is a non-base metalliferous Au depositthat contains Au/Ag ~ 1.07, As (~0.27%), F (1.59%), and a trace amount of Sb. This deposit will lead to finding new gold deposits in Eastern Taurus Orogenic Belt.

The Role of Escherichia coli Shiga Toxins in STEC Colonization of Cattle.

Many cattle are persistently colonized with Shiga toxin-producing Escherichia coli (STEC) and represent a major source of human infections with human-pathogenic STEC strains (syn. enterohemorrhagic E. coli (EHEC)). Intervention strategies most effectively protecting humans best aim at the limitation of bovine STEC shedding. Mechanisms enabling STEC to persist in cattle are only partialy understood. Cattle were long believed to resist the detrimental effects of Shiga toxins (Stxs), potent cytotoxins acting as principal virulence factors in the pathogenesis of human EHEC-associated diseases. However, work by different groups, summarized in this review, has provided substantial evidence that different types of target cells for Stxs exist in cattle. Peripheral and intestinal lymphocytes express the Stx receptor globotriaosylceramide (Gb3 syn. CD77) in vitro and in vivo in an activation-dependent fashion with Stx-binding isoforms expressed predominantly at early stages of the activation process. Subpopulations of colonic epithelial cells and macrophage-like cells, residing in the bovine mucosa in proximity to STEC colonies, are also targeted by Stxs. STEC-inoculated calves are depressed in mounting appropriate cellular immune responses which can be overcome by vaccination of the animals against Stxs early in life before encountering STEC. Considering Stx target cells and the resulting effects of Stxs in cattle, which significantly differ from effects implicated in human disease, may open promising opportunities to improve existing yet insufficient measures to limit STEC carriage and shedding by the principal reservoir host.

Genetic Diversity and Phylogeography of Thottapalayam thottimvirus (Hantaviridae) in Asian House Shrew (Suncus murinus) in Eurasia.

Murid and cricetid rodents were previously believed to be the principal reservoir hosts of hantaviruses. Recently, however, multiple newfound hantaviruses have been discovered in shrews, moles, and bats, suggesting a complex evolutionary history. Little is known about the genetic diversity and geographic distribution of the prototype shrew-borne hantavirus, Thottapalayam thottimvirus (TPMV), carried by the Asian house shrew (Suncus murinus), which is widespread in Asia, Africa, and the Middle East. Comparison of TPMV genomic sequences from two Asian house shrews captured in Myanmar and Pakistan with TPMV strains in GenBank revealed that the Myanmar TPMV strain (H2763) was closely related to the prototype TPMV strain (VRC66412) from India. In the L-segment tree, on the other hand, the Pakistan TPMV strain (PK3629) appeared to be the most divergent, followed by TPMV strains from Nepal, then the Indian-Myanmar strains, and finally TPMV strains from China. The Myanmar strain of TPMV showed sequence similarity of 79.3–96.1% at the nucleotide level, but the deduced amino acid sequences showed a high degree of conservation of more than 94% with TPMV strains from Nepal, India, Pakistan, and China. Cophylogenetic analysis of host cytochrome b and TPMV strains suggested that the Pakistan TPMV strain was mismatched. Phylogenetic trees, based on host cytochrome b and cytochrome c oxidase subunit I genes of mitochondrial DNA, and on host recombination activating gene 1 of nuclear DNA, suggested that the Asian house shrew and Asian highland shrew (Suncus montanus) comprised a species complex. Overall, the geographic-specific clustering of TPMV strains in Asian countries suggested local host-specific adaptation. Additional in-depth studies are warranted to ascertain if TPMV originated in Asian house shrews on the Indian subcontinent.

Mineralogy and geochemistry of the Berong Ni-Co laterite deposit, Palawan, Philippines

Intense weathering of the serpentinized peridotite resulted in the formation of the Berong Ni-Co laterite deposit in Palawan (Philippines). The studied laterite profiles are divided from base to top into: (i) serpentinized bedrock, (ii) saprolite horizon, and (iii) limonite horizon. Olivine in the peridotite contains a significant amount of Ni (average 0.38 wt% NiO), thus representing the main source of the ore in the laterite horizons. Six types of Ni-bearing serpentines (up to 6.65 wt% NiO) in the saprock are discriminated based on their textures and Raman signatures. Garnierite (a mixture of serpentine-, kerolite- and sepiolite-like clays) typically occurs as coatings or fracture fillings in the saprock and is characterized by strikingly high NiO content up to 34.86 wt%. Goethite and Mn-oxy-hydroxides (i.e. lithiophorite-asbolane intermediates) are the principal hosts of Ni in the limonite (up to 2.15 wt% NiO and 23.89 wt% NiO, respectively) with the latter also being the main Co carriers (up to 12.59 wt% CoO). The whole-rock XRF data show typical trends observed in other Ni laterite deposits, where Mg and Si are depleted toward the surface, and the transition metals (i.e. Fe, Al, Ni, Co, and Mn) are retained in the weathered horizons. The saprolite horizon is particularly enriched in Ni, while the lower section of the limonite horizon is enriched in Co. The mildly acidic environmental condition (pH ≤ 6.57) in the limonite horizon was found to enhance the mobilization and re-distribution of Ni from the limonite towards the lower section of the profiles. Geological observations, coupled with mineralogical and geochemical data, show that the Berong Ni-Co laterite deposit formed in two weathering processes: (i) development of the saprolite and the limonite horizons, and (ii) late precipitation of secondary phyllosilicates (i.e. garnierite), Mn-oxy-hydroxides and silica.

Partitioning and distribution of silver in sediment-hosted Cu-Ag deposits: Evidence from the Ghanzi-Chobe Belt portion of the Kalahari Copper Belt

The Khoemacau Mining (KCM) Cu-Ag deposits in northwestern Botswana are comprised of several mineralised zones, including from south to north: the Banana Zone (made up of the Chalcocite Zone, New Discovery, North Limb, South Limb Definition, and the North East Fold), Mango, Zone 5, Zone 5 North, Boseto, Zeta NE, and Zone 6. The KCM Cu-Ag deposits are characterised by two styles of mineralisation that include disseminated and structurally controlled styles of mineralisation, both typified by the scarcity of Ag-bearing minerals. Laser ablation inductively coupled mass spectrometry (LA-ICP-MS) and electron probe microanalysis (EPMA) techniques were employed to (i) track the sources of Ag by assessing the Ag budget of the sulphide phases, (ii) assess the partitioning and distribution of Ag in coexisting sulphide phases, and (iii) outline the mode of occurrence of Ag in the host sulphides. Bornite, chalcocite, wittichenite, tetrahedrite-like mineral, covellite, and galena were observed to be Ag-endowed. Bornite and tetrahedrite-like mineral are the principal hosts of Ag and contain, on average, up to 2090 and 4107 ppm Ag, respectively. But when bornite coexists with chalcocite, Ag preferentially partitions into chalcocite (mean Ag concentrations range from 423 to 1050 ppm) than in bornite (mean Ag concentrations range from 201 to 309 ppm). In the chalcocite-wittichenite assemblage, Ag partitions equally in these phases with mean concentrations of 1890 and 1854 ppm, respectively. Galena from the North East Fold contains a significant amount of Ag (mean 477 ppm) than that one from Zone 5, which is Ag-poor (mean up to 87 ppm). Unlike the spatially associated sulphides, chalcopyrite, however, is a poor host for Ag (mean concentration 1.3–104 ppm). The LA-ICP-MS data demonstrated that Ag is essentially bound in the crystal lattice of bornite, chalcocite, wittichenite, tetrahedrite-like mineral, covellite, and locally galena, as shown by the homogeneous distribution of Ag in the elemental maps, small to medium standard deviations (averaging 2–44% of the mean) and relatively flat time-resolved depth profiles. However, large variations in the Ag concentration between laser spots (averaging 51–70% of the mean) from the same sample, as observed in some bornite II grains from the New Discovery and the North East Fold mineralised zones, may indicate the presence of Ag-rich micro to nanoparticles in bornite II. The initial mineralising fluid is thought to have been saturated in Ag and precipitated Ag-rich phases in the mineralised zones southwest of the KCM Property, including the Chalcocite Zone, New Discovery, North Limb, South Limb Definition, and the North East Fold. Subsequently, it became Ag-under-saturated with time as it precipitated Ag-poor phases in the mineralised zones northeast of the KCM Project (such as Zone 5). The positive correlations (R > 0.60) displayed between Ag and As, Se, Sb, Hg, Te, and Bi in the Cu-(Fe)-sulphides demonstrate that these elements could be used as pathfinder elements in sediment-hosted Cu-Ag deposit exploration.

A latitudinal gradient of plant–insect interactions during the late Permian in terrestrial ecosystems? New evidence from Southwest China

Abstract The Permian–Triassic transition is concerned with a critical time interval during the evolutionary history of terrestrial ecosystems. However, the ecological underpinnings of terrestrial ecosystems during this time interval are poorly understood due to an impoverished fossil record. One of the more understudied episodes in the history of life is the ecological state of terrestrial ecosystems immediately before the Permian–Triassic ecological crisis. We address this issue by a quantitative study of a floral assemblage and its herbivorous insect damage based on 1086 plant specimens from the uppermost Permian of Southwest China. This bulk flora comprises 25 genera and 36 species of plants representing a typical, tropical rainforest vegetation of the upper Permian. We record 171 insect damage occurrences belonging to 24 distinctive damage types (DTs) from six functional feeding groups that were recognised in the flora. Statistical analyses of the occurrence, richness, diversity and frequency of DTs reveal that gigantopterids are the principal host plants for insect herbivores in the flora. Compared with other late Permian floras, a significant distinction of the insect damage spectrum can be recognised palaeolatitudinally based on the global position of phytogeographic regions. Despite the different, major targeted plant hosts in these floras, the richness and diversity of insect DTs and their herbivory levels from mid- to high latitudinal floras are remarkably lower than those of low latitudinal to equatorial floras. Our study indicates that terrestrial ecosystems from lower latitudes have higher levels of ecological complexity, and a distinct latitudinal gradient that probably was well established in terrestrial ecosystems during the late Permian. This assessment provides the first comprehensive overview of the ecological relationships among plants and insects, as well as their representation in terrestrial ecosystems of the late Paleozoic Cathaysia Flora.

Isotope systematics and fluid inclusion studies of the Hongtaiping Cu–Pb–Zn deposit in Yanbian, NE China: Implications for ore genesis

The Hongtaiping Cu–Pb–Zn deposit is located in the central part of the Yanbian–Dongning region, NE China, which is the eastern segment of the Central Asian Orogenic Belt. The Cu–Pb–Zn mineralization occurs in the contact zone of the Lower Permian Miaoling and Kedao formations with tuff lavas, tuffs, and marlstones as the principal host rocks. The orebodies are distributed in stratiform, stratiform‐like and lenticular morphologies, consistent with the host strata. Field investigations indicate three ore facies consisting of stringer–stockwork, massive, and laminated ores in the Hongtaiping deposit, which show apparent variation spatially from bottom to top of sulphide types. A lot of liquid‐rich fluid inclusions were identified in mineral crystals from the three types of ore facies with complete homogenization temperatures varying from 162 to 249°C and salinities in the range of 3.3 to 9.6 wt% NaCl equiv. The δD and values of calcite samples from the stringer or stockwork ores range from −82.0 to −75.1‰ and 3.3 to 3.7‰, respectively, lower than those (δD values of −64.1 to −38.8‰, values of −0.9 to 2.2‰) of the massive and laminated ores. In addition, the calcite samples show restricted δ13C values from −6.8 to −4.0‰. These fluid inclusions and H–O–C isotope geochemistry suggest that ore‐forming fluids of the Hongtaiping deposit were mainly sourced from heated seawater or brine derived, with the carbon from marine carbonates by water–rock interaction. The δ34S values of sulphide separates from the stringer–stockwork, massive and laminated ores range from −15.2 to −9.2‰ with an average value of −12.3‰. The sulphide minerals yield 206Pb/204Pb ratios from 18.025 to 19.758, 207Pb/204Pb ratios from 15.601 to 15.795, and 208Pb/204Pb ratios from 37.202 to 39.305. These S and Pb isotope compositions indicate that the sulphur had an origin in seawater sulphates from which sulphur was most possibly transformed into sulphide by thermochemical reduction, while the lead in ores originated mainly from the Miaoling Formation, with small amounts directly derived from the subvolcanic intrusion. Taken together, the Hongtaiping deposit can be classified as a volcanogenic massive sulphide (VMS) deposit, for which the possible mineralization process is interpreted in terms of a long‐lived convective circulation of mobile heated seawater mixed with some magmatic fluids along submarine faults and fissures during the Early Permian. The metals were migrated and subsequently enriched in the hydrothermal circulation system by being leached from the underlying volcanic rocks, with the metal‐rich ore‐forming fluids combined with contributions of water–rock reaction, thermochemical sulphate reduction and temperature change leading to the precipitation of polymetallic sulphides.

Evaluating the tradeoffs of a generalist parasitoid fungus, Ophiocordyceps unilateralis, on different sympatric ant hosts

It is essential for the survival and reproduction of parasitoids to adapt to the fluctuating host resources. Phenotypic plasticity may enable a parasitoid species to successfully achieve its control over a range of host species to maximize fitness in different hosts that may each require dissimilar, possibly conflicting, specific adaptations. However, there is limited information on how the fitness effects of host switching partition into costs due to the novelty of host species, where unfamiliarity with host physiological and morphological changes and its anti-parasite defenses reduces parasitoid growth, survivorship and/or reproductive success. In this study, the parasitoid fungus Ophiocordyceps unilateralis sensu lato was found to sympatrically infect a principal host ant species and other alternative sympatric hosts in the forest of central Taiwan. We herein report that the occurrence of ant infections by O. unilateralis s.l. shows spatial and temporal variation patterns on different host species. Results showed that the height from the ground to the leaf where the infected ants grip on, perithecia-forming ability, and growth rate of the stroma of the parasitoid fungus were dissimilar on different host species. These host range expansions not only related the fitness of O. unilateralis s.l. but also influenced the expression of extended phenotypic traits. Our findings revealed that a generalist parasitoid fungus suffered an evolutionary tradeoff between host breadth expansion and host-use efficiency.