Natural Niche Research Articles

An appraisal on valorization of lignin: A byproduct from biorefineries and paper industries

Lignocellulose based processes consist of technology platforms for production of materials and products for developing a bio-based, sustainable economy. Production of sugar streams and ethanol from cellulose is a mature technology, and its deployment results in increased lignin availability. Although lignin is used for low-value applications, its high-value utilization needs to be explored and developed. The aromatic intermediates from lignin can be transformed into high-value products. The unique structural/chemical properties of lignin offer possibilities for valorization, which can be achieved through thermochemical or biological transformation platforms, each route having its pros and cons. Lignin degrading oragnisms hold promise for biovalorization. In this work, different categories of organisms (fungi and bacteria) capable of degrading lignin, possessing unique repertoires of enzymes have been discussed. Under natural niches consortium of organisms decay lignin as a single organism does not possess all the activities. The constraints in biological processing can be addressed by using a combination of processes for lignin depolymerization to aromatic intermediates, followed by their conversion to target products. The recent devised metabolic engineering strategies to tackle these challenges are reviewed. Ultimately, the success of biorefineries will be dictated by the technical feasibility of bioconversions, robustness of engineered organisms, and their ability to produce the desired products in high titers with relatively high purity, scalability, and overall economics.

Candida albicans Isolates 529L and CHN1 Exhibit Stable Colonization of the Murine Gastrointestinal Tract.

ABSTRACTCandida albicans is a pathobiont that colonizes multiple niches in the body including the gastrointestinal (GI) tract but is also responsible for both mucosal and systemic infections. Despite its prevalence as a human commensal, the murine GI tract is generally refractory to colonization with the C. albicans reference isolate SC5314. Here, we identify two C. albicans isolates, 529L and CHN1, that stably colonize the murine GI tract in three different animal facilities under conditions where SC5314 is lost from this niche. Analysis of the bacterial microbiota did not show notable differences among mice colonized with the three C. albicans strains. We compared the genotypes and phenotypes of these three strains and identified thousands of single nucleotide polymorphisms (SNPs) and multiple phenotypic differences, including their ability to grow and filament in response to nutritional cues. Despite striking filamentation differences under laboratory conditions, however, analysis of cell morphology in the GI tract revealed that the three isolates exhibited similar filamentation properties in this in vivo niche. Notably, we found that SC5314 is more sensitive to the antimicrobial peptide CRAMP, and the use of CRAMP-deficient mice modestly increased the ability of SC5314 to colonize the GI tract relative to CHN1 and 529L. These studies provide new insights into how strain-specific differences impact C. albicans traits in the host and advance CHN1 and 529L as relevant strains to study C. albicans pathobiology in its natural host niche.

Global cultivation of wheat crops induces considerable shifts in the range and niche of species relative to their wild progenitors

Species’ range and niche play key roles in understanding ecological and biogeographical patterns, especially in projecting global biotic homogenization and potential distribution patterns of species under global change scenarios. However, few studies have investigated the ability of crop cultivation to influence potential range sizes and niche shifts of species. Wheat and its wild progenitors share the same origin and evolutionary history, and thus provide an excellent system to explore this topic. Using ensembled ecological niche models and niche dynamic models, we studied the potential range sizes of wheat and its wild progenitors, as well as their niche dynamics. Our results showed that wheat had larger range size and niche breadth than its wild progenitors, suggesting that wheat cultivation is a more powerful driver of range and niche expansion than natural niche evolution. Additionally, wheat and its wild progenitors occupied different niche positions, and the former did not conserve the niches inherited from the latter, implying that wheat cultivation considerably induces niche shifts. The niche dynamics between wheat and its wild progenitors were not only closely associated with cultivation but were also modified by the niche conservatism of its wild progenitors. In contrast to most invasive plants, wheat, as a global staple crop species, did not conserve the niche space inherited from its wild progenitors, suggesting that compared with most plant invasions, cultivation may have a stronger effect on niche shifts. Therefore, global niche shifts induced by crop cultivation need much more attention, though the underlying mechanisms require further study.

Molecular characterization of hematopoietic stem cells after in vitro amplification on biomimetic 3D PDMS cell culture scaffolds

Hematopoietic stem cell (HSC) transplantation is successfully applied since the late 1950s. However, its efficacy can be impaired by insufficient numbers of donor HSCs. A promising strategy to overcome this hurdle is the use of an advanced ex vivo culture system that supports the proliferation and, at the same time, maintains the pluripotency of HSCs. Therefore, we have developed artificial 3D bone marrow-like scaffolds made of polydimethylsiloxane (PDMS) that model the natural HSC niche in vitro. These 3D PDMS scaffolds in combination with an optimized HSC culture medium allow the amplification of high numbers of undifferentiated HSCs. After 14 days in vitro cell culture, we performed transcriptome and proteome analysis. Ingenuity pathway analysis indicated that the 3D PDMS cell culture scaffolds altered PI3K/AKT/mTOR pathways and activated SREBP, HIF1α and FOXO signaling, leading to metabolic adaptations, as judged by ELISA, Western blot and metabolic flux analysis. These molecular signaling pathways can promote the expansion of HSCs and are involved in the maintenance of their pluripotency. Thus, we have shown that the 3D PDMS scaffolds activate key molecular signaling pathways to amplify the numbers of undifferentiated HSCs ex vivo effectively.

Synthetic liver fibrotic niche extracts achieve in vitro hepatoblasts phenotype enhancement and expansion

SummaryIt is still a challenge for synthesizing ‘cellular niche-mimics’ in vitro with satisfactory reproducibility and fidelity to recreate the natural niche components (e.g., extracellular matrices and soluble factors) for stem cell cultivation. Inspired by the massive amplification of hepatic progenitor cells during liver fibrosis in vivo, here we optimized the in vitro liver fibrotic niches and subsequently harvested their bioactive ingredients as niche extracts (NEs). The fibrosis-relevant NE marginally outperformed Matrigel for phenotype maintenance of human embryonic stem cell (hESC)-derived hepatoblasts (HBs) and recapitulation of the pathological angiogenesis of hESC-derived endothelial cells both in 2D culture and 3D liver organoids. Finally, defined NE components (i.e., collagen III, IV, IL-17, IL-18 and M-CSF) were resolved by the quantitative proteomics which exhibited advantage over Matrigel for multi-passaged HB expansion. The pathology-relevant and tissue-specific NEs provide innovative and generalizable strategies for the discovery of optimal cellular niche and bioactive niche compositions.

Exploring the environmental traits and applications of Klebsiella variicola.

Klebsiella variicola has been found in various natural niches, alone or in association with other bacteria, and causes diseases in animals and plants with important economic and environmental impacts. K. variicola has the capacity to fix nitrogen in the rhizosphere and soil; produces indole acetic acid, acetoin, and ammonia; and dissolves phosphorus and potassium, which play an important role in plant growth promotion and nutrition. Some members of K. variicola have properties such as halotolerance and alkalotolerance, conferring an evolutionary advantage. In the environmental protection, K. variicola can be used in the wastewater treatment, biodegradation, and bioremediation of polluted soil, either alone or in association with other organisms. In addition, it has the potential to carry out industrial processes in the food and pharmaceutical industries, like the production of maltose and glucose by the catalysis of debranching unmodified oligosaccharides by the pullulanase enzyme. Finally, this bacterium has the ability to transform chemical energy into electrical energy, such as a biocatalyst, which could be useful in the near future. These properties show that K. variicola should be considered an eco-friendly bacterium with hopeful technological promise. In this review, we explore the most significant aspects of K. variicola and highlight its potential applications in environmental and biotechnological processes.

Surveillance of Listeria monocytogenes as an emerging public health threat in Domestic Animals and Human in Egypt

The present study will involve conducting surveillance for a zoonotic bacterial agent, Listeria monocytogenes in domestic animals and human in Egypt. The aim was to help in recording much more data concerning such disease and determining the most likely sources of Listeriosis infecting humans and the distribution of the various serotypes in the region. This information is important in order to optimize and determine appropriate intervention strategies and management of Listeriosis cases in animals especially ruminants and rabbits livestock. The results revealed that the occurrence of L. monocytogenes in the examined animal samples was 1.5 % (9/620) with high incidence in cows 1.3% (4/300) and in human acute blood samples was 0.8% (2/250). Most of the recovered isolates (72.7 %) showed high incidence of L. monocytogenes serotype 4 (8/11). Antibiogram was done for the recovered isolates and showed high resistance patterns for phenicols, polypeptides, cephalosporines and lincosamides. Genotypic analysis for the recovered isolates was carried out by using PCR with specific nucleotides sequence for prfA genes followed by sequencing and phylogenetic analysis. This analysis revealed that cows act as natural niches for that emerging pathogen.

Mucormycosis: A black fungus – post covid complication, clinical and pathogenic approaches and isolation and characterization of black fungus with correlate its current perspectives of biomedical waste management

The clinically relevant black yeasts and their relatives, i.e., members of the Ascomycete order Chaetothyriales. In order to understand the pathology of these fungi it is essential to know their natural ecological niche. From a relatively low degree of molecular variability of the black yeast Exophiala dermatitidis, potential agent of brain infections in patients from East Asia, it is concluded that this species is an emerging pathogen, currently going through a process of active speciation. It is found to be an oligotrophic fungus in hot, moist environments, such as steam baths. Cladophialophora-Fonsecaea- and Ramichloridium-like strains, known in humans as agents of chromoblastomycosis, are frequently found on rotten plant material, but the fungal molecular diversity in the environment is much higher than that on the human patient, so that it is difficult to trace the etiological agents of the disease with precision, Human to human transmitted disease is the game of corona virus disease (COVID-19) transmission and it had been declared an emergency global pandemic that caused major disastrous in respiratory system to more than five million people and killing more than half a billion deaths across the globe. Besides lower acute respiratory syndrome, there is damage to alveolar with severe inflammatory exudation. COVID-19 patients often have lower immunosuppressive CD4+ T and CD8+ T cells and most patients in intensive care units (ICU) need mechanical ventilation, hence longer stay in hospitals. These patients have been discovered to develop fungal co-infections. COVID-19 patients develop what is known as mucormycosis a black fungal infection which is deadly leading to loss of sight and hearing and eventually death. This chapter will focus on mucormycosis, black fungus caused during post covid complication. This approach has been successful with Cladophialophora carrionii, of which cells resembling muriform cells, the tissue form of chromoblastomycosis, were found to occur in drying spines of cacti. Phagocytosis assays provide a method to distinguish between pathogens and non-pathogens, as the killing rates of strict saprobes proved to be consistently higher than of those species frequently known as agents of disease. therapeutic possibilities for patient chromoblastomycosis. Covid-19 waste is like any other infectious waste and the guidelines for its management are required to be followed in addition to existing practices under regulation. BMWM in context of COVID-19 is a public health concern and is both a legal and social responsibility.

Ant-eating twigs and stalks: the natural prey of Tmarus and Monaeses (Araneae: Thomisidae) in the Western Palaearctic, analysed by using online-accessible wildlife photography

The diet of the Western Palaearctic species of the closely related crab spider genera Tmarus Simon, 1875 and Monaeses Thorell, 1869 is only little known. A quantitative analysis of images showing spiders with prey, collected from the World Wide Web and the literature, suggests that both genera mainly prey on ants (Hymenoptera: Formicidae), while occasionally capturing other arthropods, such as spiders (Araneae). Most images depict feeding spiders that hold ants anterior-dorsally at the articulation of head and pronotum. Tmarus galapagosensis Baert, 2013, from the Galapagos Islands, is known to attack ants by a bite to this region, which, in combination with the photographic evidence, supports the hypothesis that Western Palaearctic representatives of both genera attack ants in a similar way. Three species of Tmarus and two of Monaeses were identified from the images feeding on ants, demonstrating that probably all species of both genera at least include ants in their diet. In conclusion, Western Palaearctic Tmarus and Monaeses are myrmecophagous predators and probably have a narrow trophic niche in nature. Furthermore, both genera represent interesting model organisms for the study of trophic specialisation in widespread taxonomic clades.

Biofabrication of Artificial Stem Cell Niches in the Anterior Ocular Segment.

The anterior segment of the eye is a complex set of structures that collectively act to maintain the integrity of the globe and direct light towards the posteriorly located retina. The eye is exposed to numerous physical and environmental insults such as infection, UV radiation, physical or chemical injuries. Loss of transparency to the cornea or lens (cataract) and dysfunctional regulation of intra ocular pressure (glaucoma) are leading causes of worldwide blindness. Whilst traditional therapeutic approaches can improve vision, their effect often fails to control the multiple pathological events that lead to long-term vision loss. Regenerative medicine approaches in the eye have already had success with ocular stem cell therapy and ex vivo production of cornea and conjunctival tissue for transplant recovering patients’ vision. However, advancements are required to increase the efficacy of these as well as develop other ocular cell therapies. One of the most important challenges that determines the success of regenerative approaches is the preservation of the stem cell properties during expansion culture in vitro. To achieve this, the environment must provide the physical, chemical and biological factors that ensure the maintenance of their undifferentiated state, as well as their proliferative capacity. This is likely to be accomplished by replicating the natural stem cell niche in vitro. Due to the complex nature of the cell microenvironment, the creation of such artificial niches requires the use of bioengineering techniques which can replicate the physico-chemical properties and the dynamic cell–extracellular matrix interactions that maintain the stem cell phenotype. This review discusses the progress made in the replication of stem cell niches from the anterior ocular segment by using bioengineering approaches and their therapeutic implications.

Making space: the natural, cultural, cognitive and social niches of human activity.

This paper is in two parts. Part 1 examines the phenomenon of making space as a process involving one or other kind of legal decision-making, for example when a state authority authorizes the creation of a new highway along a certain route or of a new park in a certain location. In cases such as this, a new abstract spatial entity comes into existence - the route, theboundaries of the area to beset aside for the park - followed only later by concordant changes in physical reality. In Part 2, we show that features identified in studying this phenomenon of legal spacemaking can be detected in other spheres of human activity, for example in planning (where spacemaking is projected into the future), and in reasoning about history (where spacemaking is projected back through time). We shall see that these features display themselves in especially complex ways in our everyday use of language, and we conclude by examining the implications of this complexity for attempts to create an artificial intelligence that would enjoy a mastery of language that would be equivalent to that of human beings.

Tissue engineering of mouse uterus using menstrual blood stem cells (MenSCs) and decellularized uterine scaffold

BackgroundUterine tissue engineering can provide the opportunity for curing female infertility. Natural scaffold is a good choice to recapitulate the architecture and functionality of the native tissue. In this study, we purposed the potential of uterine decellularized scaffolds as an adequate natural niche for MenSCs differentiation toward uterus-specific cell lineages.MethodsMouse’s uterus was decellularized by immersion of hypo and hypertonic salts or freeze–thaw cycle followed by immersion in Triton X-100 and SDS solutions. MenSCs were isolated from the menstrual blood of 6 healthy women. The decellularized and recellularized samples were prepared for further in vitro and in vivo analyses.ResultsHistochemical studies and Raman spectroscopy revealed uterine ECM was preserved well, and the cells were completely removed after decellularization. Scanning electron microscopy (SEM) showed that the 3D ultrastructure of the uterus remained intact. Flowcytometric examination with CD34, CD44, CD105, CD106, CD144 markers revealed stem cell characters of cells that isolated from menstrual blood. MTT assay confirmed the bioavailability of MenSCs cultured scaffolds after 7 and 10 days.ConclusionHistochemical studies, SEM images, and Raman spectra showed MenSCs seeded and growth in uterine scaffolds. Immunostaining using anti-cytokeratin (CK), anti-desmin (Des), anti-vimentin (Vim), and anti-smooth muscle actin (SMA) antibodies showed MenSCs differentiation to epithelial and smooth muscle tissues. The Raman spectroscopy revealed the extracellular matrix (ECM) of decellularized uterine scaffolds was well preserved. The decellularized uterus can be considered a promising vehicle to support cell transplantation and differentiation. MenSCs are a good choice for uterine tissue engineering. The complete decellularization from mice uterine tissue was done by combining chemical agents

Review on Population Status and Conservation Activity of Indigenous Cattle Breeds of Ethiopia

Ethiopia has the home to at least 27 cattle breeds and an estimated 59.5 million head of cattle due to its diversified agroecology and topography and directly serves as for millions of people. Indigenous cattle breed has many important traits compared with exotic cattle breeds. Bos indicus breeds can effectively regulate their body temperature against thermal stress and are better adapted to hot weather than Bos taurus breeds. In addition, several breeds of Zebu and Zenga are able to withstand very harsh environmental conditions, and those characteristics have arisen through evolutionary adaptation. For examples, Begait cattle (Large East African Zebu) found in North-Western Ethiopia are well adapted to very dry climates and they can survive if they are able to drink only once every two days. However, despite the potential of the indigenous livestock currently, the genetic resources are becoming seriously endangered due to high genetic erosion resulting from biotic and abiotic factors. The objective of this review was to highlight threats, conservation methods and improvement activities currently done for indigenous cattle genetic resources in Ethiopia. Based on the review, among the world 1458 breeds all domestic mammalian and avian species, 17% are classified as being at risk and 58% are classified as unknown risk status. The major threats of livestock genetic resources are genetic dilution through the use of exotic germ plasma, feed shortage, illegal trafficking, inbreeding and interbreeding, and trypanosomiasis disease. This situation demands immediate action to save deteriorating genetic resources in the country. Some of endangered indigenous cattle breeds were conserved in ex-situ method at different state ranches, the Borana cattle breed as Did Tuyura Ranch, Horro cattle breed at Horro Ranch, Fogera cattle breed at Metekel Ranch and Andassa Agricultural Research Centre, and Menz sheep breed at Amed Guya Research Centre but, the results were not enough. Therefore, phenotypic and genotypic categorization of breeds will be further characterized, monitor the current population statistics, conservation of breeds under natural niche, and improvement programs will be implemented for all breeds and also improve the productivity of grazing land.

Review on Population Status and Conservation Activity of Indigenous Cattle Breeds of Ethiopia

Ethiopia has the home to at least 27 cattle breeds and an estimated 59.5 million head of cattle due to its diversified agroecology and topography and directly serves as for millions of people. Indigenous cattle breed has many important traits compared with exotic cattle breeds. Bos indicus breeds can effectively regulate their body temperature against thermal stress and are better adapted to hot weather than Bos taurus breeds. In addition, several breeds of Zebu and Zenga are able to withstand very harsh environmental conditions, and those characteristics have arisen through evolutionary adaptation. For examples, Begait cattle (Large East African Zebu) found in North-Western Ethiopia are well adapted to very dry climates and they can survive if they are able to drink only once every two days. However, despite the potential of the indigenous livestock currently, the genetic resources are becoming seriously endangered due to high genetic erosion resulting from biotic and abiotic factors. The objective of this review was to highlight threats, conservation methods and improvement activities currently done for indigenous cattle genetic resources in Ethiopia. Based on the review, among the world 1458 breeds all domestic mammalian and avian species, 17% are classified as being at risk and 58% are classified as unknown risk status. The major threats of livestock genetic resources are genetic dilution through the use of exotic germ plasma, feed shortage, illegal trafficking, inbreeding and interbreeding, and trypanosomiasis disease. This situation demands immediate action to save deteriorating genetic resources in the country. Some of endangered indigenous cattle breeds were conserved in ex-situ method at different state ranches, the Borana cattle breed as Did Tuyura Ranch, Horro cattle breed at Horro Ranch, Fogera cattle breed at Metekel Ranch and Andassa Agricultural Research Centre, and Menz sheep breed at Amed Guya Research Centre but, the results were not enough. Therefore, phenotypic and genotypic categorization of breeds will be further characterized, monitor the current population statistics, conservation of breeds under natural niche, and improvement programs will be implemented for all breeds and also improve the productivity of grazing land. Keywords: conservation, indigenous, cattle, breed, threat, Ethiopia DOI: 10.7176/JBAH/11-16-01 Publication date: August 31 st 2021

Microbial cell factories for the production of polyhydroxyalkanoates.

Pollution caused by persistent petro-plastics is the most pressing problem currently, with 8 million tons of plastic waste dumped annually in the oceans. Plastic waste management is not systematized in many countries, because it is laborious and expensive with secondary pollution hazards. Bioplastics, synthesized by microorganisms, are viable alternatives to petrochemical-based thermoplastics due to their biodegradable nature. Polyhydroxyalkanoates (PHAs) are a structurally and functionally diverse group of storage polymers synthesized by many microorganisms, including bacteria and Archaea. Some of the most important PHA accumulating bacteria include Cupriavidus necator, Burkholderia sacchari, Pseudomonas sp., Bacillus sp., recombinant Escherichia coli, and certain halophilic extremophiles. PHAs are synthesized by specialized PHA polymerases with assorted monomers derived from the cellular metabolite pool. In the natural cycle of cellular growth, PHAs are depolymerized by the native host for carbon and energy. The presence of these microbial PHA depolymerases in natural niches is responsible for the degradation of bioplastics. Polyhydroxybutyrate (PHB) is the most common PHA with desirable thermoplastic-like properties. PHAs have widespread applications in various industries including biomedicine, fine chemicals production, drug delivery, packaging, and agriculture. This review provides the updated knowledge on the metabolic pathways for PHAs synthesis in bacteria, and the major microbial hosts for PHAs production. Yeasts are presented as a potential candidate for industrial PHAs production, with their high amenability to genetic engineering and the availability of industrial-scale technology. The major bottlenecks in the commercialization of PHAs as an alternative for plastics and future perspectives are also critically discussed.

Evolution of land use in coal-based cities based on the ecological niche theory: A case study in Shuozhou City, China

With the rapid development changes and the special land-use patterns, coal-based cities (CBCs) have faced many critical sustainability issues such as the effective use of land resources, the mitigation of land supply-demand contradictions. How does the development of CBCs in China affected local land-use changes and what status does each land type occupy? The relevant mechanisms are not clear. Shuozhou City, a typical growth CBC in China, was therefore selected as the research area to investigate the land use evolution by introducing the theory of land use ecological niche (LUEN). The dynamic changes of land use from 1990 to 2018 were analyzed, and cultivated land played a significant role in the process of land transformation with the highest utilization degree, followed by grassland and construction land. The cultivated land and mining land occupied the economic niche, construction land occupied the social niche, and forest land, grassland, and water area occupied the natural niche. From 2010 to 2015, construction land and mining land occupied the prevailing position of the land-use system. The substantial expansion and compression of the land use ecological niche in Shuozhou City were in the early stage of city development, and there was not a major change in the later stage. In general, the spatial distribution of land use ecological niche was in the east-west direction. Therefore, the production function zone, living function zone, and ecological function zone were delineated. The status, role, and function of land use type should be prioritized when developing land-use planning, considering the mechanisms of land-use change. Governments should actively break through the restrictions of coal resources mining on land use change while giving full play to the role of land resource assets in promoting sustainable development.

Domiciliation and sympatry of Triatoma maculata and Rhodnius prolixus, risk of Trypanosoma cruzi transmission in villages of Anzoátegui, Venezuela.

The domiciliation of Triatoma maculata and Rhodnius prolixus and the entomological risk indicators for the transmission of Trypanosoma cruzi, an etiological agent of Chagas Disease-CD, were studied in rural villages of Anzoátegui state, Venezuela. Nightly home visits were made for 4months/year, for 2years, to search for and capture triatomines in human settlements. For six of the evaluated villages, 16.4% (11/67) of houses were found with triatomine infestation; obtaining 151 triatomines in all their ontogenetic stages, of which 54.3% (82/151) corresponded to T. maculata and 45.7% (69/151) to R. prolixus. In 7.5% of the evaluated houses, both species were presented in sympatry. Entomological indicators of transmission risk were higher for T. maculata in relation to R. prolixus. Inoculation of fecal flagellates of triatomines produced 2.92 × 105 flagellates/mL of blood in mean and 100% mortality in the murine model. Molecular tests (satellite DNA, kDNA and DTUs studies) demonstrated the presence of T. cruzi, all compatible with TcI. The food source determined by IESPA, revealed that R. prolixus showed less eclecticism in relation to T. maculata in the use of blood sources. This could be an indicator of an older domiciliation with low dispersion between ecotopes. The sympatry of T. maculata and R. prolixus had been recorded in natural niches, but for the first time it is recorded inside the houses in rural villages of the Anzoátegui state. Human dwellings can constitute an adequate niche, with available food sources for both triatomines species and with the risk of establishing AT/CD as zoonosis or zooanthroponosis.

How to Teach about What Is a Species.

Simple SummaryWhat is a species? According to the biospecies concept, organisms that can mate with each other belong to a species, e.g., Homo sapiens. But does this adequately explain to us what a species is? No! With the help of the biospecies concept, we can only recognize species, but we cannot explain them. To understand what a species is, we must ask ourselves and our students if a species is real—a thing with properties (comparable to an individual)—or just a concept, a natural class of organisms with largely equivalent characteristics.To ask students what a species is always has something rhetorical about it. Too quickly comes the rote answer, often learned by heart without ever thinking about it: “A species is a reproductive community of populations (reproductively isolated from others), which occupies a specific niche in nature” (Mayr 1982). However, do two people look alike because they are twins or are they twins because they look alike? “Two organisms do not belong to the same species because they mate and reproduce, but they only are able to do so because they belong to the same species” (Mahner and Bunge 1997). Unfortunately, most biology (pre-university) teachers have no opinion on whether species are real or conceptual, simply because they have never been taught the question themselves, but rather one answer they still pass on to their students today, learned by heart without ever thinking about it. Species are either real or conceptual and, in my opinion, it is this “or” that we should teach about. Only then can we discuss those fundamental questions such as who or what is selected, who or what evolves and, finally, what is biodiversity and phylogenetics all about? Individuals related to each other by the tree of life.

Spatial distribution of LTi-like cells in intestinal mucosa regulates type 3 innate immunity

Lymphoid tissue inducer (LTi)-like cells are tissue resident innate lymphocytes that rapidly secrete cytokines that promote gut epithelial integrity and protect against extracellular bacterial infections.Here, we report that the retention of LTi-like cells in conventional solitary intestinal lymphoid tissue (SILT) is essential for controlling LTi-like cell function and is maintained by expression of the chemokine receptor CXCR5. Deletion of Cxcr5 functionally unleashed LTi-like cells in a cell intrinsic manner, leading to uncontrolled IL-17 and IL-22 production. The elevated production of IL-22 in Cxcr5-deficient mice improved gut barrier integrity and protected mice during infection with the opportunistic pathogen Clostridium difficile Interestingly, Cxcr5-/- mice developed LTi-like cell aggregates that were displaced from their typical niche at the intestinal crypt, and LTi-like cell hyperresponsiveness was associated with the local formation of this unconventional SILT. Thus, LTi-like cell positioning within mucosa controls their activity via niche-specific signals that temper cytokine production during homeostasis.

Invasive Group B Streptococcus Disease With Recurrence and in Multiples: Towards a Better Understanding of GBS Late-Onset Sepsis.

Group B Streptococcus (GBS) is a common intestinal colonizer during the neonatal period, but also may cause late-onset sepsis or meningitis in up to 0.5% of otherwise healthy colonized infants after day 3 of life. Transmission routes and risk factors of this late-onset form of invasive GBS disease (iGBS) are not fully understood. Cases of iGBS with recurrence (n=25) and those occurring in parallel in twins/triplets (n=32) from the UK and Ireland (national surveillance study 2014/15) and from Germany and Switzerland (retrospective case collection) were analyzed to unravel shared (in affected multiples) or fixed (in recurrent disease) risk factors for GBS disease. The risk of iGBS among infants from multiple births was high (17%), if one infant had already developed GBS disease. The interval of onset of iGBS between siblings was 4.5 days and in recurrent cases 12.5 days. Disturbances of the individual microbiome, including persistence of infectious foci are suggested e.g. by high usage of perinatal antibiotics in mothers of affected multiples, and by the association of an increased risk of recurrence with a short term of antibiotics [aOR 4.2 (1.3-14.2), P=0.02]. Identical GBS serotypes in both recurrent infections and concurrently infected multiples might indicate a failed microbiome integration of GBS strains that are generally regarded as commensals in healthy infants. The dynamics of recurrent GBS infections or concurrent infections in multiples suggest individual patterns of exposure and fluctuations in host immunity, causing failure of natural niche occupation.