Original Host Research Articles

Interaction between the parasitic barnacle Polyascus planus (Cirripedia: Rhizocephala) and its brachyuran host Metopograpsus thukuhar during the development of the externa of the parasite: Control of the gonadal development and vitellogenin synthesis of the host

Developmental profile of the female reproductive apparatus (the externa) of Polyascus planus parasitizing the thukuhar shore-crab Metopograpsus thukuhar is described. The development is divided into 4 stages, which are named based on the distinct color of the externa at each stage. The effects of parasitism on the gonad and hepatopancreas of the host were then examined. The ovary was heavily infiltrated by the rootlet of the parasite, with the oocytes being arrested at the pre-vitellogenic state, whereas the testis, not being infiltrated, still contained abundant amounts of spermatozoa. The hepatopancreas of the hosts of both sexes was heavily infiltrated by the rootlets. Regarding the synthesis of vitellogenin (Vg), the hemolymph precursor of the major yolk protein (vitellin, Vn), expression of host Vg gene was detected in the ovary and hepatopancreas of both non-parasitized and parasitized females, and, importantly, its expression found to be induced in the hepatopancreas of parasitized males. Furthermore, results of quantitative gene expression assays showed that expression levels of the host Vg in the ovary and hepatopancreas did not change significantly among the various parasitization status (i.e., host bearing externa of different developmental stages), nor did those of the parasite Vg in the externa among the developmental stage of the externa. The Vg expression levels in the hepatopancreas of parasitized males and in the externa were however negatively correlated. Finally, analysis of tryptic peptide fragments derived from hemolymph proteins of high molecular weight in the parasitized males confirmed the induction of synthesis of the host Vg, whereas analysis of externa proteins of similar molecular weight revealed that Vg of both host and parasite origins contributes to the formation of parasite Vn. The combined results indicate that the parasitized hosts, regardless of sex, synthesize Vg for the ovarian maturation of the parasite, to which Vg of parasite origin also contributes. Discussion is also made with regard to the strategy the parasite adopts toward hosts of different sexes. The profile of the development of externa established would serve as a temporal framework against which studies of host/parasite interaction can be conducted in a developmental context.

Size and shape variation of Hypsipyla grandella Zeller (Lepidoptera: Pyralidae) in two hosts: A morphometric approach

The mahogany shoot borer (Hypsipyla grandella) attacks different Meliaceae species and impedes its plantation. Its biology is poorly known, but some results show a preference for Cedrela odorata L. over Swietenia macrophylla King, which could generate intraspecific variations. We studied the effect of these hosts on H. grandella right-forewing size and shape variation, using a geometric morphometry approach. We collected larvae in plantations of each host, rose them in seedlings of the same original host and set 13 landmarks on 63 right-forewings. Sexual-shape dimorphism was present and the right-forewings of individuals collected in C. odorata were larger. Removing the allometric effect and comparing magnitude and direction in the plastic responses of the sexual-shape dimorphism, we only found differences in the direction. Differences in the right-forewing shape within sexes were present when comparing hosts and removing the allometric effects. Only the right-forewing of males differs between hosts in terms of shape. The differences found could influence the species' flying system. Individuals with the larger right-forewings could be more frequent in C. odorata plated areas, with an increased ability for long-distance flights, which is undesired in integrated pest management systems.

The Evolutionary Dynamics of Infectious Diseases on an Unstable Planet: Insights from Modeling the Stockholm Paradigm

Emerging infectious diseases (EIDs) are, besides a question of food safety and public health, an ecological and evolutionary issue. The recognition of this condition combined with the accumulation of evidence that pathogens are not specialists in their original hosts evidences the need for understanding how the dynamics of interaction between pathogens and hosts occurs. The Stockholm Paradigm (SP) provides the theoretical fundaments to understand the dynamics of diseases and design proactive measures to avoid the emergence and reemergence of infectious diseases. In this review, we revisit the models that evaluate several aspects of the proposed dynamics of the SP, including the complexity nature of the elements that have been associated with this new framework for the evolution of associations. We integrate the results from these studies into a putative dynamic of infectious diseases, discuss subordinate elements of this dynamic, and provide suggestions on how to integrate these findings into the DAMA (Document, Assess, Monitor, Act) protocol.

Characteristics, pathogenic mechanism, zoonotic potential, drug resistance, and prevention of avian pathogenic Escherichia coli (APEC).

Although most Escherichia coli (E. coli) strains are commensal and abundant, certain pathogenic strains cause severe diseases from gastroenteritis to extraintestinal infections. Extraintestinal pathogenic E. coli (ExPEC) contains newborn meningitis E. coli (NMEC), uropathogenic E. coli (UPEC), avian pathogenic E. coli (APEC), and septicemic E. coli (SEPEC) based on their original host and clinical symptom. APEC is a heterogeneous group derived from human ExPEC. APEC causes severe respiratory and systemic diseases in a variety of avians, threatening the poultry industries, food security, and avian welfare worldwide. APEC has many serotypes, and it is a widespread pathogenic bacterium in poultry. In addition, ExPEC strains share significant genetic similarities and similar pathogenic mechanisms, indicating that APEC potentially serves as a reservoir of virulence and resistance genes for human ExPEC, and the virulence and resistance genes can be transferred to humans through food animals. Due to economic losses, drug resistance, and zoonotic potential, APEC has attracted heightened awareness. Various virulence factors and resistance genes involved in APEC pathogenesis and drug resistance have been identified. Here, we review the characteristics, epidemiology, pathogenic mechanism zoonotic potential, and drug resistance of APEC, and summarize the current status of diagnosis, alternative control measures, and vaccine development, which may help to have a better understanding of the pathogenesis and resistance of APEC, thereby reducing economic losses and preventing the spread of multidrug-resistant APEC to humans.

Redescription of Holocolax nemipteri (Pilllai, 1973) (Copepoda, Cyclopoida, Bomolochidae) parasitic on the Japanese threadfin bream Nemipterus japonicus (Bloch, 1791) (Pisces, Nemipteridae) in Japan, with description of copepodid III sex undetermined of the species

Abstract Holocolax nemipteri (Pillai, 1973) is redescribed based on specimens of the female recovered from the bucco-branchial cavity of the original host, the Japanese threadfin bream Nemipterus japonicus (Bloch, 1791) in Japan. Copepodid III sex undetermined of the species recovered from the same host is described for the first time in the genus.

Host and abiotic constraints on the distribution of the pine fungal pathogen Sphaeropsis sapinea (= Diplodia sapinea)

Plant fungal pathogens are an increasing emerging threat as climate change progresses. Sphaeropsis sapinea (syn. Diplodia sapinea), the causal fungal agent of Diplodia tip blight, is a major pathogen of pines of forestry and ornamental relevance in Europe and worldwide. Here, we combined molecular-based field surveys in a common-garden setting and across an elevation gradient with historical records, cultivation-based growth experiments and microscopy to report on host and abiotic constraints on the distribution of S. sapinea. Using the arboretum at the Botanical Garden Berlin, Germany, to control for environmental variability, S. sapinea was detected on all seven host Pinus species we studied. However, P. sylvestris is the only species in which the fungus was detected in symptomless needles at the arboretum, and the most frequently recorded host for over a century, suggesting that it is the main, and perhaps, potential original host. In addition, sampling symptomatic needles in four out of the seven same species across a gradient from 200 to 2,100 m of elevation in the French Alps, S. sapinea was not detected at elevation higher than 800 m. Abiotic constraints were also supported by reduced growth of isolates of S. sapinea at low temperature under controlled conditions, but a 35°C prior stress exposure increased the subsequent growth of S. sapinea within its optimal temperature range (20-30°C). Altogether, our study thus not only suggests that S. sapinea is more likely to cause tip blight in P. sylvestris compared to the other species we studied, but also that in the current context of global climate change with predicted temperature increases, the fungus could infect a wider range of pine hosts and locations worldwide.

First report of intra-species morphological variation of Fasciola gigantica from different host origins (cattle and buffalo)

First report of intra-species morphological variation of Fasciola gigantica from different host origins (cattle and buffalo)

Simultaneous detection of odontoglossum ringspot virus (ORSV) and cymbidium mosaic virus (CymMV) infecting orchids in Meghalaya, India by Multiplex RT-PCR

• ORSV was found to be more prevalent than CymMV with the incidence percentages of 53.5% and 46.4% respectively. • Mixed infection of ORSV and CymMV was found to be 35.7%. • The Nucleotide sequences of ORSV and CymMV CP genes from Meghalaya showed high sequence identities of 96.90–99.56% and 96.91–99.66% respectively with other available sequences in Genbank. Odontoglossum ringspot virus (ORSV) and cymbidium mosaic virus (CymMV) are the most prevalent viruses infecting orchids all around the world. These viruses cause a serious threat to the orchid industry as they can spread from infected plants to healthy plants through vegetative propagation, contaminated tools, and human hands. This result in negative vigour of infected plants, showing stunted growth, producing fewer flowers, and decreasing flower quality. In this study, 84 leaf samples of orchids were collected from nine horti-hubs and orchid nurseries in Meghalaya. The orchid leaf samples were subjected to multiplex RT-PCR amplification using gene-specific primers targeting the coat protein (CP) genes of CymMV and ORSV. The most prevalent virus detected was ORSV with a 53.5% incidence while CymMV showed a 46.4% incidence. Mixed infections of ORSV and CymMV were detected in 30 samples (35.7%). The nucleotide sequences of ORSV and CymMV CP genes from Meghalaya showed high sequence identities of 96.90–99.56% and 96.91–99.66%, respectively when compared to other sequences in GenBank. The phylogenetic relationship among ORSV isolates and CymMV, based on infected host or geographical origin, showed no clear-cut clustering of isolates.

Strong Genetic Differentiation between Generalist Populations of Venturia inaequalis and Populations from Partially Resistant Apple Cultivars Carrying Rvi3 or Rvi5

The ascomycete fungus Venturia inaequalis causes scab disease, a major problem in apple production. The utilization of resistant cultivars is hindered by emerging new pathogen races, which erode their resistance. Increasing our knowledge on the population genetic processes of the fungus can contribute to the development of resistance gene deployment strategies and more durable resistance. We investigated the effect of four scab race indicator cultivars, ‘Gala’ (no R-gene), ‘Golden Delicious’ (Rvi1), ‘Geneva’ (Rvi3, complex), and OR45t132 (Rvi5), on the V. inaequalis population genetic structure and diversity. Sixty-six monosporic fungal isolates from the four cultivars were genotyped with seven simple sequence repeat primers. Furthermore, the partial resistance of the indicators and the pathogenicity profile of the conidia from each host were assessed. The genetic diversity and structure of the investigated V. inaequalis subpopulations correspond to the partial resistance of the original hosts as well as the subpopulations’ pathogenicity profiles. Indicators carrying Rvi3 and Rvi5 had strongly diverged and specialized V. inaequalis populations on them and fewer symptoms on the field. In line with the complete breakdown of the Rvi1 gene, the population from ‘Golden Delicious’ did not segregate from the susceptible ‘Gala’, and virulence towards Rvi1 was present in all subpopulations.

Nature-inspired Material – A Step Ahead in Dental Materials

Glass-ionomer is first choice widely used biomaterial in caries disease. The evolution of dental material science includes insertion of new components into conventional material. A literature-based review outline of biomaterials for dental restorations development was presented in nature-inspired context. This article is a tribute to the entire research community, for all listed and unlisted, involved throughout the ages in the science of dental materials with the key inventions and milestones for humanity well-being on Earth. Results. Since the Neolithic, the human mind has been seeking for a matter to replace missing tooth tissue imitating/mimicking natural organ in appearance and function, what we call biomimetic/biomimicry approach. However, this restoring philosophy does not refer to the natural composition of hard tooth tissues. Possibly, there is another one concept of drawing inspiration from nature for the design of future dental materials. Nature-inspired synthesis goes beyond aesthetic/and anatomical similarities, and delves into the mechanistic, physico-chemical features or structure-phase of natural systems. In this context, pure glass-ionomer might be taken into consideration as a starting material. However, the search for synthetic nature-inspired mesomaterial with a structural-phase composition analogous to enamel/dentine/cementum, transforming into the original host hard tissues, should focus on elongated hydroxyapatite dipole control for creating and organizing into enamel prisms, and the interwoven alignment of perpendicular clusters/bunches in a picket-fence resembling three-dimensional order. The results of previous studies confirming the possibility of the formation of apatite-enamel-like tissue in glass-ionomer are promising. The concept of inclusion of calcium phosphate nanocrystals/substitution of glass filler seems to be forward-looking. The future role of polyelectrolyte organic matrix based on synthetic tooth polypeptides crosslinked with modified analogues of natural adhesives is still undiscovered.

The Mechanisms of Systemic Inflammatory and Immunosuppressive Acute-on-Chronic Liver Failure and Application Prospect of Single-Cell Sequencing.

Acute-on-chronic liver failure (ACLF) is a complex clinical syndrome, and patients often have high short-term mortality. It occurs with intense systemic inflammation, often accompanied by a proinflammatory event (such as infection or alcoholic hepatitis), and is closely related to single or multiple organ failure. Liver inflammation begins when innate immune cells (such as Kupffer cells (KCs)) are activated by binding of pathogen-associated molecular patterns (PAMPs) from pathogenic microorganisms or damage-associated molecular patterns (DAMPs) of host origin to their pattern recognition receptors (PRRs). Activated KCs can secrete inflammatory factors as well as chemokines and recruit bone marrow-derived cells such as neutrophils and monocytes to the liver to enhance the inflammatory process. Bacterial translocation may contribute to ACLF when there are no obvious precipitating events. Immunometabolism plays an important role in the process (including mitochondrial dysfunction, amino acid metabolism, and lipid metabolism). The late stage of ACLF is mainly characterized by immunosuppression. In this process, the dysfunction of monocyte and macrophage is reflected in the downregulation of HLA-DR and upregulation of MER tyrosine kinase (MERTK), which weakens the antigen presentation function and reduces the secretion of inflammatory cytokines. We also describe the specific function of bacterial translocation and the gut-liver axis in the process of ACLF. Finally, we also describe the transcriptomics in HBV-ACLF and the recent progress of single-cell RNA sequencing as well as its potential application in the study of ACLF in the future, in order to gain a deeper understanding of ACLF in terms of single-cell gene expression.

Micro RNAs-The Small Big Players in Hepatitis E Virus Infection: A Comprehensive Review.

The molecular mechanism of hepatitis E virus (HEV) pathology is still unclear. The micro RNAs (miRNAs), of host or viral origin, interfere with virus replication and host environment in order to create an appropriate condition for the production of mature HEV progeny. Understanding the biogenesis and the interference of miRNAs with HEV will help to revile the mechanism of viral pathogenesis.

Comparative genomic and transcriptomic analyses of trans-kingdom pathogen Fusarium solani species complex reveal degrees of compartmentalization

BackgroundThe Fusarium solani species complex (FSSC) comprises fungal pathogens responsible for mortality in a diverse range of animals and plants, but their genome diversity and transcriptome responses in animal pathogenicity remain to be elucidated. We sequenced, assembled and annotated six chromosome-level FSSC clade 3 genomes of aquatic animal and plant host origins. We established a pathosystem and investigated the expression data of F. falciforme and F. keratoplasticum in Chinese softshell turtle (Pelodiscus sinensis) host.ResultsComparative analyses between the FSSC genomes revealed a spectrum of conservation patterns in chromosomes categorised into three compartments: core, fast-core (FC), and lineage-specific (LS). LS chromosomes contribute to variations in genomes size, with up to 42.2% of variations between F. vanettenii strains. Each chromosome compartment varied in structural architectures, with FC and LS chromosomes contain higher proportions of repetitive elements with genes enriched in functions related to pathogenicity and niche expansion. We identified differences in both selection in the coding sequences and DNA methylation levels between genome features and chromosome compartments which suggest a multi-speed evolution that can be traced back to the last common ancestor of Fusarium. We further demonstrated that F. falciforme and F. keratoplasticum are opportunistic pathogens by inoculating P. sinensis eggs and identified differentially expressed genes also associated with plant pathogenicity. These included the most upregulated genes encoding the CFEM (Common in Fungal Extracellular Membrane) domain.ConclusionsThe high-quality genome assemblies provided new insights into the evolution of FSSC chromosomes, which also serve as a resource for studies of fungal genome evolution and pathogenesis. This study also establishes an animal model for fungal pathogens of trans-kingdom hosts.

A molecular characterization of marsupial filarioid nematodes of the genus Breinlia.

Here we present the genetic relationships of 26 specimens of the genus Breinlia (Nematoda: Filarioidea) from a range of Australian marsupials using markers in the small subunit of nuclear ribosomal RNA and mitochondrial cytochrome c oxidase subunit 1 (cox1) genes and compare them with morphological determinations. The molecular data support the validity of most of the morpho-species included in the study and provide provisional insights into the phylogeny of the genus in Australian mammals, with dasyuroid marsupials appearing to be the original hosts. The recent discovery of Breinlia annulipapillata in the eye of a human brings this genus of parasites into the group of emerging infectious parasitic diseases.

The Characterization of the Tobacco-Derived Wild Tomato Mosaic Virus by Employing Its Infectious DNA Clone.

Simple SummaryWild tomato mosaic virus (WTMV, genus Potyvirus, family Potyviridae) is an emerging viral pathogen that endangers Nicotiana tabacum production. The field survey conducted in this study shows that WTMV is becoming an epidemic in China. An infectious DNA clone of the tobacco-derived WTMV is constructed. It can infect wild eggplant, black nightshade, and tobacco plants but can not infect various local pepper varieties. WTMV evolves into three groups that coincide with their original hosts, tobacco, pepper, or wild eggplant. Thus, the tobacco-derived WTMV might divergently evolves to adapt to tobacco other than peppers. We show that WTMV is compatible with the coinfection of cucumber mosaic virus (CMV) or tobacco mosaic virus (TMV) in tobacco but not other potyviruses. Specifically, WTMV can interfere with the infection of other potyvirus species in tobacco, a phenomenon known as superinfection exclusion previously observed within the same potyviral species. This study contributes essential knowledge on the evolution, infectivity, and recent epidemics of WTMV, and provides the key tool for further disease-resistance and field management studies.Viral diseases of cultivated crops are often caused by virus spillover from wild plants. Tobacco (N. tabacum) is an important economic crop grown globally. The viral pathogens of tobacco are traditional major subjects in virology studies and key considerations in tobacco breeding practices. A positive-strand RNA virus, wild tomato mosaic virus (WTMV), belonging to the genus potyvirus in the family potyviridae was recently found to infect tobacco in China. In this study, diseased tobacco leaf samples were collected in the Henan Province of China during 2020–2021. Several samples from different locations were identified as WTMV positive. An infectious DNA clone was constructed based on one of the WTMV isolates. By using this clone, we found that WTMV from tobacco could establish infections on natural reservoir hosts, demonstrating a possible route of WTMV spillover and overwintering in the tobacco field. Furthermore, the WTMV infection was found to be accompanied by other tobacco viruses in the field. The co-inoculation experiments indicate the superinfection exclusion (SIE) between WTMV and other potyvirus species that infect tobacco. Overall, our work reveals novel aspects of WTMV evolution and infection in tobacco and provides an important tool for further studies of WTMV.

CORONAVIRUSES AND POTENTIAL VACCINES

It is believed that CoVs might have been transmitted to humans via animals. Those causing SARS, MERS and COVID-19 probably have originated from bats. Possibly the transfer of the new CoV strain from the original host species to humans must have involved another animal species which acted as an intermediate host. The SARS-CoV-2, is most closely related to a group of SARS-CoVs found in humans, bats, pangolins and civets. As the virus was new, it potentially infected very large numbers of people all around the globe and thus resulted into pandemic. Even though the number of very severe cases was low in terms of percentage but taking it into terms of number it becomes a very large count of people with acute illness. SARS-CoV-2 infected patients reportedly develop low titre neutralizing antibody and usually suffered prolonged illness, that showed a more effective SARS-CoV-2 immune surveillance evasion when compared with SARS-CoV. Various treatments were tried and different vaccines were tested out to ght against this deadly virus all around the globe. In this article , a brief review of information on different CoVs and its various vaccine has been made.

In-depth investigation of microRNA-mediated cross-kingdom regulation between Asian honey bee and microsporidian.

Asian honey bee Apis cerana is the original host for Nosema ceranae, a unicellular fungal parasite that causes bee nosemosis throughout the world. Currently, interaction between A. cerana and N. ceranae is largely unknown. Our group previously prepared A. c. cerana workers’ midguts at 7 days post inoculation (dpi) and 10 dpi with N. ceranae spores as well as corresponding un-inoculated workers’ midguts, followed by cDNA library construction and a combination of RNAs-seq and small RNA-seq. Meanwhile, we previously prepared clean spores of N. ceranae, which were then subjected to cDNA library construction and deep sequencing. Here, based on the gained high-quality transcriptome datasets, N. ceranae differentially expressed mRNAs (DEmiRNAs) targeted by host DEmiRNAs, and A. c. cerana DEmRNAs targeted by microsporidian DEmiRNAs were deeply investigated, with a focus on targets involved in N. ceranae glycolysis/glyconeogenesis as well as virulence factors, and A. c. cerana energy metabolism and immune response. In A. c. cerana worker’s midguts at 7 (10) dpi (days post inoculation), eight (seven) up-regulated and six (two) down-regulated miRNAs were observed to target 97 (44) down-regulated and 60 (15) up-regulated N. ceranae mRNAs, respectively. Additionally, two up-regulated miRNAs (miR-60-y and miR-676-y) in host midgut at 7 dpi could target genes engaged in N. ceranae spore wall protein and glycolysis/gluconeogenesis, indicating potential host miRNA-mediated regulation of microsporidian virulence factor and energy metabolism. Meanwhile, in N. ceranae at 7 (10) dpi, 121 (110) up-regulated and 112 (104) down-regulated miRNAs were found to, respectively, target 343 (247) down-regulated and 138 (110) down-regulated mRNAs in A. c. cerana workers’ midguts. These targets in host were relevant to several crucial cellular and humoral immune pathways, such as phagasome, endocytosis, lysosomes, regulation of autophagy, and Jak–STAT signaling pathway, indicative of the involvement of N. ceranae DEmiRNAs in regulating these cellular and humoral immune pathways. In addition, N. ceranae miR-21-x was up-regulated at 7 dpi and had a target relative to oxidative phosphorylation, suggesting that miR-21-x may be used as a weapon to modulate this pivotal energy metabolism pathway. Furthermore, potential targeting relationships between two pairs of host DEmiRNAs-microsporidian DEmRNAs and two pairs of microsporidian DEmiRNAs-host DEmRNAs were validated using RT-qPCR. Our findings not only lay a foundation for exploring the molecular mechanism underlying cross-kingdom regulation between A. c. cerana workers and N. ceranae, but also offer valuable insights into Asian honey bee-microsporidian interaction.

Unveiling Mycoviromes Using Fungal Transcriptomes.

Viruses infecting fungi are referred to as mycoviruses. Here, we carried out in silico mycovirome studies using public fungal transcriptomes mostly derived from mRNA libraries. We identified 468 virus-associated contigs assigned to 5 orders, 21 families, 26 genera, and 88 species. We assembled 120 viral genomes with diverse RNA and DNA genomes. The phylogenetic tree and genome organization unveiled the possible host origin of mycovirus species and diversity of their genome structures. Most identified mycoviruses originated from fungi; however, some mycoviruses had strong phylogenetic relationships with those from insects and plants. The viral abundance and mutation frequency of mycoviruses were very low; however, the compositions and populations of mycoviruses were very complex. Although coinfection of diverse mycoviruses in the fungi was common in our study, most mycoviromes had a dominant virus species. The compositions and populations of mycoviruses were more complex than we expected. Viromes of Monilinia species revealed that there were strong deviations in the composition of viruses and viral abundance among samples. Viromes of Gigaspora species showed that the chemical strigolactone might promote virus replication and mutations, while symbiosis with endobacteria might suppress virus replication and mutations. This study revealed the diversity and host distribution of mycoviruses.

Fluid-driven cyclic reorganization in shallow basaltic fault zones

Abstract Faults represent a critical heterogeneity in basaltic sequences, yet few studies have focused on their architectural and hydromechanical evolution. We present a detailed, multi-scale characterization of passively exhumed fault zones from the layered basalts of the Faroe Islands, which reveals cyclic stages of fault evolution. Outcrop-scale structures and fault rock distribution within the fault zones were mapped in the field and in 3-D virtual outcrop models, with detailed characterization of fault rock microstructure obtained from optical and scanning electron microscopy. The fault zones record deformation localization from decameter-wide Riedel shear zones into meter-wide fault cores that contain multiple cataclastic shear bands and low-strain lenses organized around a central slip zone. Shear bands and the slip zone consist of (ultra-) cataclasites with a zeolite-smectite assemblage replacing the original plagioclase-pyroxene host rock composition. Low-strain lenses are breccias of weakly altered host rock or reworked fault rocks. Slip zone-proximal zones show significant late-stage dilatation in the form of hydrothermal breccias or tabular veins with up to decimeter apertures. We interpret these structures as evolving from alternating shear-compaction and dilation through hydrofracture. The fault core preserves slip zone reworking, which is interpreted to indicate repeated shear zone locking and migration. The alternating deformation styles of shear-compaction and dilatation suggest episodic changes in deformation mechanisms driven by transient overpressure and release. The fault zone mechanical properties are thus governed by the combined effects of permanent chemical weakening and transient fluid-mediated mechanical weakening, alternating with cementation and healing. We suggest that the model presented for fault evolution should apply widely to shallow, basalt-hosted fault zones.

Novel Ca and Ca-Li Intercalated B/C and B/C/N Materials with Layered Structures

Abstract Boron/carbon/nitrogen (B/C/N) materials and boron/carbon (B/C) materials having graphite-like layered structures were synthesized by using a chemical vapor deposition (CVD) method. Calcium (Ca) was intercalated into the B/C materials by the reaction of Ca vapor with the host B/C film to form an intercalation compound with a second stage structure as a main product. Ca was also co-intercalated with lithium (Li) into the B/C/N materials by using a liquid-alloy method to form an intercalation compound. These are the first examples of syntheses of Ca and Ca-Li intercalated B/C and B/C/N materials. A nuclear microprobe analysis (NMA) indicated the compositions of the original host B/C/N and B/C materials to be BC2.6N0.55 and BC6.4, and the Ca-Li intercalated compound to be Ca0.67Li0.42(BC3.3N0.50) and suggested the homogeneity of these materials and the compound. We also found that the NMA is one of the most accurate methods for determining the compositions of air and water sensitive intercalation compounds as well as complex systems like B/C/N and B/C materials.