Different Classes Of Vertebrates Research Articles

Disentangling drivers of vertebrate roadkill in a protected area in the Amazon rainforest

AbstractVertebrates' roadkill impacts many species in natural areas. However, data on this topic in the Amazon domain are still scarce, especially within protected areas. In this study, we analysed data from 2 years of monitoring amphibians, reptiles, mammals and birds' roadkill on five types of terrestrial transport infrastructure in a protected area in the Brazilian Amazon. We tested which vertebrate classes and feeding guilds were most recorded, the influence of seasonality and the spatial pattern of roadkill. In the studied area, 2795 roadkills were recorded, with amphibians suffering the most casualties. Most of the roadkills occurred during the rainy season (57%). Correcting the roadkill data using observer efficiency and carcass persistence time data, we concluded that mortality rates might be underestimated by up to 40 times when compared to raw data. There was no significant difference between feeding guilds concerning the number of fatalities, and rainfall and temperature significantly affected the roadkill pattern of all vertebrate classes. The spatial pattern of roadkill varied between traffic routes and vertebrate class types. The results indicate that amphibians are the most common victims of roadkill, although they are neglected in many roadkill monitoring. Consequently, mitigation strategies should prioritize periods with the highest mortality rates, as rainfall and temperature influence the frequency of these accidents. In addition, different classes of vertebrates have different patterns of impact concentration along traffic routes, which makes mitigation planning more complex. Therefore, planning to reduce vertebrate deaths from roadkill must consider each taxon's particularity and seasonality.

Understanding the role of temperature in seasonal timing: Effects on behavioural, physiological and molecular phenotypes

AbstractOrganisms adapt to daily and seasonal environmental changes to maximise their metabolic and reproductive fitness. For seasonally breeding animals, photoperiod is considered the most robust cue to drive these changes. It, however, does not explain the interannual variations in different seasonal phenotypes. Several studies have repeatedly shown the influence of ambient temperature on the timing of different seasonal physiologies including the timing of migration, reproduction and its associated behaviours, etc. In the present review, we have discussed the effects of changes in ambient temperature on different seasonal events in endotherms with a focus on migratory birds as they have evolved to draw benefits from distinct but largely predictable seasonal patterns of natural resources. We have further discussed the physiological and molecular mechanisms by which temperature affects seasonal timings. The primary brain area involved in detecting temperature changes is the hypothalamic preoptic area. This area receives thermal inputs via sensory neurons in the peripheral ganglia that measure changes in thermoregulatory tissues such as the skin and spinal cord. For the input signals, several thermal sensory TRP (transient receptor potential ion channels) channels have been identified across different classes of vertebrates. These channels are activated at specific thermal ranges. Once perceived, this information should activate an effector function. However, the link between temperature sensation and the effector pathways is not properly understood yet. Here, we have summarised the available information that may help us understand how temperature information is translated into seasonal timing.

The Main Patterns of Transformation in Organs of Reproductive System During the Evolution of Vertebrates

The article presents an analysis of the main directions of transformations of the organs of the reproductive system during the evolution of vertebrates at various levels of the hierarchical organization of vertebrates - cellular, tissue, organ, organism, population. During the evolution of vertebrates, gonadal oligomerization occurred, a decrease in the number of hermaphrodite species, a decrease in the relative mass of gonads in the body, and a transition from isogamy to heterogamy (oogamy) was observed. In vertebrates, 4 types of structural and functional organization of male gonads have been formed: follicular type, follicular-cystic type, tubular-cystic type, tubular type. In representatives of different classes of vertebrates, the transformation of the ovaries proceeded in different directions. Large, grape-shaped ovaries have evolved in fish, amphibians, reptiles, birds, and cloacal mammals. These ovaries, just before the breeding season, can occupy almost the entire abdominal cavity. The ovaries of placental mammals are small in size, their shape is most often oval, the surface is smooth. One of the directions of the evolutionary transformation of the gonads was the compartmentalization of the structures of the male and female gonads, while there was a structural and topographic division into the actual gonads and the genital tract, which were formed on the basis of the structures of the primary kidney. Higher vertebrates have well-developed accessory sex glands. In the gonads, there was a clear topographical distinction between endocrine and germinal structures. Against the background of an increase in the number of species with internal fertilization, against the background of the formation of a complexly organized vagina and uterus in female mammals, the formation and complication of the copulatory organs of males occurred.

Lake Guidimouni: Diversity of Vertebrate Fauna and its Threats

Lakes provide many services to humanity. However human activities affect negatively the function of the lakes to deliver their values to society. It is in this sense, this study tried to assess the effects of human activities on the dryland lake (Lake Guidimouni) mostly, the effects of the human activities on the vertebrate fauna. This study will close the paucity of data about the diversity of vertebrate fauna in the West African Sahel Lake. Therefore, this study assessed the diversity of vertebrate fauna and its menaces in Lake Guidimouni, Niger. We used Field investigations and questionnaires for the data collection. While we used descriptive statistics and the number of species, the number of families of the different classes of vertebrates recorded in the lake. The study recorded 21 vertebrate fauna species across the four vertebrate classes (Fish species = 7; Bird species = 7; Amphibian species = 2 and reptile species = 5) in the lake Guidimouni based on the field observation and questionnaire. More specifically the study recorded six fish species belonging to the six families in the lake with as Cichlidae dominant family. While we recorded seven bird species with Ardeidae having the high species richness (3 species) belonging to three families. Furthermore, five species of reptile were recorded belonging five families in the lake Guidimouni. Lastly, two amphibian species were identified belonging to two families. Secondly, the study documented the many threats to Lake Guidimouni biodiversity mainly illegal poaching, salinity, the use of the chemicals, overexploitation such as overfishing, invasion by species such as Typha australis and Prosopis juliflora, destruction of the lake by unsustainable farming practices such as cutting down of trees and drying up of the lake. This study constitutes the baseline reference about the impacts of human activities on the dryland lake (lake Guidimouni) in Zinder region, in Niger. The study recommends some ecological restoration activities of lake Guidimouni such as the removal of the invasive species, enforcement of law and regulation about the use of chemicals in the lake. It also recommends further study which look at socio-economic and ecological benefits of the lake Guidimouni in the context of changing climate.

Hox genes in the coordination of embryonic development. Model of hourglass in the description of vertebrate ontogenesis

The paper analyzes the role of HOX genes in the processes of embryonic development of vertebrates. Based on the analysis, it is concluded that HOX genes are the most important regulators of embryonic development. The HOX genes predominantly realize their influence through specific HOX proteins that have the ability to regulate the expression of target genes.
 The order of expression of the HOX genes, as a rule, obeys the rule of temporal and spatial colinearity. This mechanism determines the temporal and spatial course of tissue morphogenesis during embryonic development and tissue regeneration in organisms that have reached the stage of maturity.
 The process of embryo morphogenesis, determined by highly conserved HOX genes, explains the appearance of the phylotypic period - the stage of embryonic development of vertebrates, at which embryos of different classes of vertebrates have distinct morphological similarities.

Neuronal regeneration: Vertebrates comparative overview and new perspectives for neurodegenerative diseases

AbstractNeurodegenerative diseases afflict a significant percentage of the world's population. The human nervous system is unable to regenerate after an insult, or due to senility, while low vertebrates still exhibit this ability. Comparative neurobiology can increase knowledge about neuronal degeneration and regeneration. Anamni vertebrates retain the ability to regenerate up to large areas of the nervous system. The regenerative ability of central nervous system components depends on the phylogenetic distance between classes of vertebrates. It decreases during evolution. Teleosts can skilfully regenerate brain, spinal cord and retina. Amphibians and reptiles can only regenerate certain areas; spinal cord regeneration in reptiles is limited to axonal regrowth. Retina regeneration is possible in bird embryo but not in the adult. In this review, we analyse how the regeneration of neurons occurs in different classes of vertebrates, and how the study of these mechanisms could be applied to the search for new therapies for neurodegenerative disorders.

The Aromatase-Estrogen System in the Testes of Non-Mammalian Vertebrates.

Simple SummaryThe aromatase–estrogen system plays a key role in gonadal sex differentiation in amphibians, reptiles, and birds during development. In adults of seasonal breeding species, aromatase activity and estrogen levels can act as an “on/off” switch for spermatogenesis and can also promote spermiogenesis.Estrogens are important physiological regulators of testicular activity in vertebrates. Estrogen levels depend on the activity of P450 aromatase, the enzyme responsible for the irreversible conversion of testosterone into 17β-estradiol. Therefore, P450 aromatase is the key player in the aromatase–estrogen system. The present review offers a comparative overview of P450 aromatase activity in male gonads of amphibians, reptiles, and birds, with a particular emphasis on the functions of the aromatase–estrogen system in these organisms during their developmental and adult stages. The aromatase–estrogen system appears to be crucial for the sex differentiation of gonads in vertebrates. Administration of aromatase inhibitors prior to sexual differentiation of gonads results in the development of males rather than females. In adults, both aromatase and estrogen receptors are expressed in somatic cells, Leydig and Sertoli cells, as well as germ cells, with certain differences among different species. In seasonal breeding species, the aromatase–estrogen system serves as an “on/off” switch for spermatogenesis. In some amphibian and reptilian species, increased estrogen levels in post-reproductive testes are responsible for blocking spermatogenesis, whereas, in some species of birds, estrogens function synergistically with testosterone to promote spermatogenesis. Recent evidence indicates that the production of the aromatase enzyme in excessive amounts reduces the reproductive performance in avian species of commercial interest. The use of aromatase inhibitors to improve fertility has yielded suitable positive results. Therefore, it appears that the role of the aromatase–estrogen system in regulating the testicular activity differs not only among the different classes of vertebrates but also among different species within the same class.

Salivary Glands of Vertebrates: Ecological, Morphological and Evolutionary Aspects

The aim of the study was to compare ecological and morphological features and evolutionary dynamics of the salivary glands in representatives of different classes of vertebrates living in different ecological conditions.Material and methods. The glandular structures of the tongue of vertebrates belonging to various taxonomic and ecological groups (fish, amphibians, reptiles, mammals) were studied. The material obtained was processed using histological and histochemical methods.The results of the study demonstrated that in the course of the evolutionary transformations of vertebrates, an increase and complication of the glandular structures of the tongue occurred due to changes in the environmental factors and in the nature of nutrition and food consumed. The evolutionary transformations of the glandular structures of the organ was directed from unicellular intraepithelial glandular structures (for example, in fish) to the complex multicellular salivary glands of higher mammals, in which there was a division into terminal secretory sections and secretory pathways. In the course of evolution, the number of functions performed by the salivary glands of the tongue has also increased. The digestive and endocrine functions were added to the function of protecting the mucous organ from damage. The serous glands of the tongue are phylogenetically younger. Their occurrence is associated with the participation of the glands of the tongue in the initial stages of chemical food processing. The preservation of more ancient mucous glands against the background of the emergence of new organisms in the course of evolution - mucoserous, seromucous and serous glands, - indicates that in the course of evolutionary development, the glandular structures of the tongue demonstrate parallelism of divergent changes.

No sex differences in adult telomere length across vertebrates: a meta-analysis.

In many mammalian species, females live on average longer than males. In humans, women have consistently longer telomeres than men, and this has led to speculation that sex differences in telomere length (TL) could play a role in sex differences in longevity. To address the generality and drivers of patterns of sex differences in TL across vertebrates, we performed meta-analyses across 51 species. We tested two main evolutionary hypotheses proposed to explain sex differences in TL, namely the heterogametic sex disadvantage and the sexual selection hypotheses. We found no support for consistent sex differences in TL between males and females among mammal, bird, fish and reptile species. This absence of sex differences in TL across different classes of vertebrates does not support the heterogametic sex disadvantage hypothesis. Likewise, the absence of any negative effect of sexual size dimorphism on male TL suggests that sexual selection is not likely to mediate the magnitude of sex differences in TL across vertebrates. Finally, the comparative analyses we conducted did not detect any association between sex differences in TL and sex differences in longevity, which does not support the idea that sex differences in TL could explain the observed sex differences in longevity.

The Features of the Structural Organization of Spinal Ganglia in a Subphylum of Vertebtates

Abstract The paper presents the results of research and studied the morphology of spinal ganglia in representatives of different classes of vertebrates: bony fish, amphibians, reptiles, birds and mammals, differing by level of organization, locomotion, habitat. It is revealed that certain structural and morphofunctional restructuring of spinal ganglia is carried out in the process of phylogenesis. Adaptation to different conditions of existence was accompanied by a change in the number of parameters of the spinal ganglia: density and size of neurocytes, increasing of the total number of gliocytes and perineuronal glial cells, polymorphism of neurocytes to the degree of chromatophily.

Comparative Histomorphology of the Ovary and the Oviduct in Rabbits and Pigeons

Introduction Knowledge of the evolutionary relationship between different classes of vertebrates can be obtained through a comparative study of their structures, forms, functions, and of the mode of development of the structures. Birds and mammals are vertebrates with different modes of reproduction, that is, oviparity in birds and viviparity in mammals. The aim of the present study is to compare the histomorphology of the ovaries and of the oviducts/uterine tubes in rabbits and pigeons. The present study highlights the histological and morphological differences that bring about the production of eggs in birds and the production of fully developed fetuses in mammals. Materials and Methods Five rabbits and five domestic pigeons were anesthetized with chloroform and sacrificed. The ovaries and the oviducts/uterine tubes were dissected and fixed in Bouin fluid and processed for a light microscopic study. Results The result showed paired ovaries and uterine tubes in rabbits that unite at the isthmus to form a single uterus that opens into the vagina, with only the left ovary and oviduct appearing as a compact body with distinct infundibulum, magnum, isthmus, uterus and vagina in pigeons. Photomicrographs of the ovaries of rabbits showed parenchyma cells with primary follicles, while the ovaries of pigeons showed developing follicles and yolk granules. Both the oviducts of rabbits and of pigeons showed a highly folded mucosa with a thick muscular wall. Conclusion The differences observed in the structures of the ovaries and of the oviducts of rabbits and pigeons might be due to their different reproductive functions in parturition (viviparity and oviparity, respectively).

An ecoimmunological approach to study evolutionary and ancient links between coagulation, complement and Innate immunity

ABSTRACT Coagulation, complement, and innate immunity are tightly interwoven and form an alliance that can be traced back to early eukaryotic evolution. Here we employed an ecoimmunological approach using Tissue Factor Pathway Inhibitor (TFPI)-1-derived peptides from the different classes of vertebrates (i.e. fish, reptile, bird, and mammals) and tested whether they can boost killing of various human bacterial pathogens in plasma. We found signs of species-specific conservation and diversification during evolution in these peptides that significantly impact their antibacterial activity. Though all peptides tested executed bactericidal activity in mammalian plasma (with the exception of rodents), no killing was observed in plasma from birds, reptiles, and fish, pointing to a crucial role for the classical pathway of the complement system. We also observed an interference of these peptides with the human intrinsic pathway of coagulation though, unlike complement activation, this mechanism appears not to be evolutionary conserved.

Constraints and Catalysts in Cerebellar Evolution

The cerebellum comprises a remarkably stereotyped neural circuit, elements of which, such as the granule cell‐Purkinje cell synapse, are highly conserved across vertebrates. It functions as an adaptive filter that can be employed in regulating feed forward control of movement, but has a wider range of functions including in mammals, a demonstrable role in cognitive development. The range of neural functions modulated by cerebellar activity is a product of its output connections. In many species these are mediated by cerebellar nuclei whose number and projections vary systematically across major classes of vertebrates. Notably, the connection of cerebellar nuclei to the thalamus and hence the ability of the cerebellum to participate in forebrain activity is a mammalian innovation. Cerebellum size is also a key adaptive variable amongst different species with some species of both fish and mammals displaying relatively large, elaborately foliated cerebellum. Different strategies for generating large numbers of cells are adopted by different classes of vertebrates. In particular, the appearance of a transient, external granule cell layer (EGL) in cerebellar development is a tetrapod innovation. In some reptiles, birds and mammals, the EGL becomes a proliferative layer, which leads to a rapid clonal expansion of granule cells and the potential for foliation. Both the diversification of connectivity (cerebellar nuclei) and transit amplification (in the EGL) are adaptive properties within derivatives of a single defined pool of progenitors at the embryonic “rhombic lip”. Different derivatives are generated within distinct cohorts. Within these cohorts the heterochronic shift in the expression of a small number of genes appears to be responsible for generating the key changes in cerebellar development in vertebrates.Support or Funding InformationMedical Research Council, UKBBSRCThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Dynamics of cytochemical parameters of pseudoeosinophils in the blood of guineafow

The cytochemical organization of neutrophils and pseudoeosinophils in different classes of vertebrates is poorly studied. The purpose of this study is to determine the cytochemical status of pseudoeosinophils in the blood of guineafowl. We analyzed the blood of Volga white guineafowl breed, colored blue and gray-speckled guineafowl populations (174, 186, and 208 days) and one-day-old nestlings of these populations. It was found that the changes in cytochemical blood cell parameters during the period of development (days 174–208) were multidirectional: the activity of acid phosphatase and glycogen increased, while the activity of myeloperoxidase and alkaline phosphatase decreased. The activity rates of myeloperoxidase and lysosomal-cationic proteins during this period were stable.

The BH4 domain of Bcl-2 orthologues from different classes of vertebrates can act as an evolutionary conserved inhibitor of IP3 receptor channels

Ca2+ signalling plays an important role in various physiological processes in vertebrates. In mammals, the highly conserved anti-apoptotic B-cell lymphoma-2 (Bcl-2) protein is an important modulator of the inositol 1,4,5-trisphosphate receptor (IP3R), i.e. the main intracellular Ca2+ - release channel located at the endoplasmic reticulum (ER). The Bcl-2 Homology (BH) 4 domain of Bcl-2 (BH4-Bcl-2) is a critical determinant for inhibiting IP3Rs, by directly targeting a region in the modulatory domain of the receptor (domain 3). In this paper, we aimed to track the evolutionary history of IP3R regulation by the BH4 domain of Bcl-2 orthologues from different classes of vertebrates, including Osteichthyes, Amphibia, Reptilia, Aves and Mammalia. The high degree of conservation of the BH4 sequences correlated with the ability of all tested peptides to bind to the domain 3 of mouse IP3R1 in GST-pull downs and their overall ability to inhibit IP3-induced Ca2+ release (IICR) in permeabilized cells. Nevertheless, the BH4 domains differed in their potency to suppress IICR. The peptide derived from X. laevis was the least potent inhibitor. We identified a critical residue in BH4-Bcl-2 from H. sapiens, Thr7, which is replaced by Gly7 in X. laevis. Compared to the wild type X. laevis BH4-Bcl-2, a “humanized” version of the peptide (BH4-Bcl-2 Gly7Thr), displayed increased IP3R-inhibitory properties. Despite the differences in the inhibitory efficiency, our data indicate that the BH4 domain of Bcl-2 orthologues from different classes of vertebrates can act as a binding partner and inhibitor of IP3R channels.

Search for conserved amino acid residues of the α-crystallin proteins of vertebrates.

[Formula: see text]-crystallin is the major eye lens protein and a member of the small heat-shock protein (sHsp) family. [Formula: see text]-crystallins have been shown to support lens clarity by preventing the aggregation of lens proteins. We performed the bioinformatics analysis of [Formula: see text]-crystallin sequences from vertebrates to find conserved amino acid residues as the three-dimensional (3D) structure of [Formula: see text]-crystallin is not identified yet. We are the first who demonstrated that the N-terminal region is conservative along with the central domain for vertebrate organisms. We have found that there is correlation between the conserved and structured regions. Moreover, amyloidogenic regions also correspond to the structured regions. We analyzed the amino acid composition of [Formula: see text]-crystallin A and B chains. Analyzing the occurrence of each individual amino acid residue, we have found that such amino acid residues as leucine, serine, lysine, proline, phenylalanine, histidine, isoleucine, glutamic acid, and valine change their content simultaneously in A and B chains in different classes of vertebrates. Aromatic amino acids occur more often in [Formula: see text]-crystallins from vertebrates than on the average in proteins among 17 animal proteomes. We obtained that the identity between A and B chains in the mammalian group is 0.35, which is lower than the published 0.60.

Lectin histochemistry of intestinal carbohydrate determinants in representatives of different classes of vertebrates.

Background. Glycoproteins (including mucin) of vertebrate’s intestine play an important role in its protection against chemical and mechanical damage and bacterial attacks. Their diversity was described by many authors, but understanding of their chemical structure remains far from complete. These data can be extended by methods of lectin histochemistry. Objective. To investigate the rearrangement of intestinal carbohydrate determinants in the context of vertebrate evolution. Methods. Distal and proximal segments of small and large intestines of humans (Homo sapiens), laboratory (Wistar) rat (Rattus norvegicus f. Domesticus), rock pigeon (Columba livia), smooth snake (Coronella austriaca), common frog (Rana temporaria), common carp (Cyprinus carpio) that belong to different classes of vertebrates were taken for the experiment. Nine lectins with different carbohydrate specificities: wheat germ (WGA), potato (STA), elderberry bark (SNA), golden rain bark (LABA), locust bark (RPBA), roe carp (CCRA), Phaseolus vulgaris erytroagglutinin (PHA-E), peanut (PNA) and jack fruit (AIA) – were included into the panel. Results. Differences in lectin staining between small and large intestine were more pronounced in higher (human, rat) than in lower (frog, carp) vertebrates. Lectin receptors were more diverse in frog intestine in comparison with carp. Lectin interaction with mucin secretory granules of smooth snake revealed lack of N-acetyl-D-glucosamine residues and abundance of N-acetyl-D-galactosamine determinants. Conclusion. Intestines of all studied vertebrate species demonstrate high content of secretory mucins that exposed terminal acidic carbohydrates including sialic acid. The diversity and differences in the structure of glycans of the digestive tract of vertebrates is apparently determined by several factors – diet, environmental and living conditions, intestinal microbiota interactions etc.

Adaptation-induced modification of motion selectivity tuning in visual tectal neurons of adult zebrafish.

In the developing brain, training-induced emergence of direction selectivity and plasticity of orientation tuning appear to be widespread phenomena. These are found in the visual pathway across different classes of vertebrates. Moreover, short-term plasticity of orientation tuning in the adult brain has been demonstrated in several species of mammals. However, it is unclear whether neuronal orientation and direction selectivity in nonmammalian species remains modifiable through short-term plasticity in the fully developed brain. To address this question, we analyzed motion tuning of neurons in the optic tectum of adult zebrafish by calcium imaging. In total, orientation and direction selectivity was enhanced by adaptation, responses of previously orientation-selective neurons were sharpened, and even adaptation-induced emergence of selectivity in previously nonselective neurons was observed in some cases. The different observed effects are mainly based on the relative distance between the previously preferred and the adaptation direction. In those neurons in which a shift of the preferred orientation or direction was induced by adaptation, repulsive shifts (i.e., away from the adapter) were more prevalent than attractive shifts. A further novel finding for visually induced adaptation that emerged from our study was that repulsive and attractive shifts can occur within one brain area, even with uniform stimuli. The type of shift being induced also depends on the difference between the adapting and the initially preferred stimulus direction. Our data indicate that, even within the fully developed optic tectum, short-term plasticity might have an important role in adjusting neuronal tuning functions to current stimulus conditions.

Vertebrate biodiversity losses point to a sixth mass extinction

The human race faces many global to local challenges in the near future. Among these are massive biodiversity losses. The 2012 IUCN/SSC Red List reported evaluations of ~56 % of all vertebrates. This included 97 % of amphibians, mammals, birds, cartilaginous fishes, and hagfishes. It also contained evaluations of ~50 % of lampreys, ~38 % of reptiles, and ~29 % of bony fishes. A cursory examination of extinction magnitudes does not immediately reveal the severity of current biodiversity losses because the extinctions we see today have happened in such a short time compared to earlier events in the fossil record. So, we still must ask how current losses of species compare to losses in mass extinctions from the geological past. The most recent and best understood mass extinction is the Cretaceous terminal extinction which ends at the Cretaceous–Paleogene (K–Pg) border, 65 MYA. This event had massive losses of biodiversity (~17 % of families, >50 % of genera, and >70 % of species) and exterminated the dinosaurs. Extinction estimates for non-dinosaurian vertebrates at the K–Pg boundary range from 36 to 43 %. However, there remains much uncertainty regarding the completeness, preservation rates, and extinction magnitudes of the different classes of vertebrates. Fuzzy arithmetic was used to compare recent vertebrate extinction reported in the 2012 IUCN/SSC Red List with biodiversity losses at the end of K–Pg. Comparisons followed 16 different approaches to data compilation and 288 separate calculations. I tabulated the number of extant and extinct species (extinct + extinct in the wild), extant island endemics, data deficient species, and so-called impaired species [species with IUCN/SSC Red List designations from vulnerable (VU) to critically endangered (CR)]. Species that went extinct since 1500 and since 1980 were tabulated. Vertebrate extinction moved forward 24–85 times faster since 1500 than during the Cretaceous mass extinction. The magnitude of extinction has exploded since 1980, with losses about 71–297 times larger than during the K–Pg event. If species identified by the IUCN/SSC as critically endangered through vulnerable, and those that are data deficient are assumed extinct by geological standards, then vertebrate extinction approaches 8900–18,500 times the magnitude during that mass extinction. These extreme values and the great speed with which vertebrate biodiversity is being decimated are comparable to the devastation of previous extinction events. If recent levels of extinction were to continue, the magnitude is sufficient to drive these groups extinct in less than a century.

A member of the Tlr family is involved in dsRNA innate immune response in Paracentrotus lividus sea urchin

The innate immune response involves proteins such as the membrane receptors of the Toll-like family (TLRs), which trigger different intracellular signalling pathways that are dependent on specific stimulating molecules. In sea urchins, TLR proteins are encoded by members of a large multigenic family composed of 60–250 genes in different species. Here, we report a newly identified mRNA sequence encoding a TLR protein (referred to as Pl-Tlr) isolated from Paracentrotus lividus immune cells. The partial protein sequence contained the conserved Toll/IL-1 receptor (TIR) domain, the transmembrane domain and part of the leucine repeats. Phylogenetic analysis of the Pl-Tlr protein was accomplished by comparing its sequence with those of TLRs from different classes of vertebrates and invertebrates. This analysis was suggestive of an evolutionary path that most likely represented the course of millions of years, starting from simple organisms and extending to humans. Challenge of the sea urchin immune system with poly-I:C, a chemical compound that mimics dsRNA, caused time-dependent Pl-Tlr mRNA up-regulation that was detected by QPCR. In contrast, bacterial LPS injury did not affect Pl-Tlr transcription. The study of the Tlr genes in the sea urchin model system may provide new perspectives on the role of Tlrs in the invertebrate immune response and clues concerning their evolution in a changing world.