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The internal representation of numbers on the mental number line (MNL) was demonstrated by performing the computerized version of the number-to-position (CNP) task on a touchscreen while restricting response time. We found that the estimation pattern is best fit by a sigmoid function, further denoted as the "sigmoidal model". Two developmental leaps occurring during elementary school were recognized: (1) the division of the number line into two segments and (2) consistent use of different anchor points on the number line—the left endpoint in first grade, the right endpoint in second grade, and finally the midpoint in third grade. Additionally, when examining the differences between the breakpoints, we found that first graders demonstrated a breakpoint close to 6, which linearly decreased over the years until stabilizing close to 5. The relation between the ability to place individual numbers on a number line and performance of mental arithmetic showed that the consistent use of anchor points correlated significantly with faster responses in mental arithmetic. [ABSTRACT FROM AUTHOR]

This article discusses Jewish women who emigrated from Islamic countries to the State of Israel during the 1950s. When they arrived in the country, they encountered a secular establishment that had originated in Europe (Ashkenazic) and possessed an entirely different culture than that of these women, who were religious and had come from Africa and Asia (Mizrahim). Alongside the secular establishment, they also encountered a small ultra-Orthodox community, which had its origins in Europe. The religious customs of this group differed greatly from those of the émigrés from Africa and Asia. In this society, the role of the woman is to financially support her sons and husbands, who immerse themselves in the study of Torah for numerous years after marriage. The article focuses on the manner in which the role of these Mizrahi women was configured and strengthened after their demise, by political leaders and rabbis, in accordance with the paradigm of contemporary Ashkenazic ultra-Orthodox society. The primary research tools are obituaries of first-generation immigrant women, authored by the male political elite in the weekly party newspaper, throughout the late twentieth and early twenty-first centuries. The findings are that ultra-Orthodox Mizrahi party in Israel—the Shas party—is shaping a new religious society for Jewish immigrants from Africa and Asia. This society's current ideal was never extant outside of Israel. It also differs from women's traditional Diaspora role as homemakers. The uniqueness of these findings lies in their evidence regarding the manner in which the party creates this society by shaping a new image of deceased immigrant women. [ABSTRACT FROM AUTHOR]

Aim: The aim was to determine how reptile populations respond to anthropogenic habitat modification and determine whether species traits and environmental factors influence such responses. Location: Global. Time period: 1981–2018. Major taxa studied: Squamata. Methods: We compiled a database of 56 studies reporting how habitat modification affects reptile abundance and calculated standardized mean differences in abundance (Hedges' g). We used Bayesian meta‐analytical models to test whether responses to habitat modification depended on body size, clutch size, reproductive mode, habitat specialization, range size, disturbance type, vegetation type, temperature and precipitation. Results: Based on 815 effect sizes from 376 species, we found an overall negative effect of habitat modification on reptile abundance (mean Hedges' g = −0.43, 95% credible intervals = −0.61 to −0.26). Reptile abundance was, on average, one‐third lower in modified compared with unmodified habitats. Small range sizes and small clutch sizes were associated with more negative responses to habitat modification, although the responses were weak and the credible intervals overlapped zero. We detected no effects of body size, habitat specialization, reproductive mode (egg‐laying or live‐bearing), temperature or precipitation. Some families exhibited more negative responses than others, although overall there was no phylogenetic signal in the data. Mining had the most negative impacts on reptile abundance, followed by agriculture, grazing, plantations and patch size reduction, whereas the mean effect of logging was neutral. Main conclusions: Habitat modification is a key cause of reptile population declines, although there is variability in responses both within and between species, families and vegetation types. The effect of disturbance type appeared to be related to the intensity of habitat modification. Ongoing development of environmentally sustainable practices that ameliorate anthropogenic impacts is urgently needed to prevent declines in reptile populations. [ABSTRACT FROM AUTHOR]

This article examines religious and spiritual beliefs of students at a secular college in Israel and their impact on the students' daily lives. The students include Jews and Bedouins studying education and sciences. The research is quantitative and used 2 questionnaires, distributed in 2011 and 2016. A small difference was found between education and science students, and a significant one between Bedouin and Jewish students. The Bedouin students, by a significant margin, come from more religious homes than the Jewish students, and most are studying education, whereas the Jewish student population is divided between students of education and science. [ABSTRACT FROM AUTHOR]

Viviparity (live‐bearing) has independently evolved from oviparity (egg‐laying) in more than 100 lineages of squamates (lizards and snakes).We might expect consequent shifts in selective forces to affect per‐brood reproductive investment (RI = total mass of offspring relative to maternal mass) and in the way in which that output is partitioned (number vs. size of offspring per brood). Based on the assumption that newly born offspring are heavier than eggs, we predicted that live‐bearing must entail either increased RI or a reduction in offspring size and/or fecundity.However, our phylogenetically controlled analysis of data on 1,259 squamate species revealed no significant differences in mean offspring size, clutch size or RI between oviparous and viviparous squamates.We attribute this paradoxical result to (1) strong selection on offspring sizes, unaffected by parity mode, (2) the lack of a larval stage in amniotes, favouring large eggs even in the ancestral oviparous mode and (3) the ability of viviparous females to decrease the mass of uterine embryos by reducing extra‐embryonic water stores.Our analysis shows that squamate eggs (when laid) weigh about the same as the hatchlings that emerge from them (despite a many‐fold increase in embryo mass during incubation). Most of the egg mass is due to components (such as water stores and the eggshell) not required for oviductal incubation. That repackaging enables live‐born offspring to be accommodated within the mother's body without increasing total litter mass.The consequent stasis in reproductive burden during the evolutionary transition from oviparity to viviparity may have facilitated frequent shifts in parity modes. [ABSTRACT FROM AUTHOR]

Aim: Variation in body size across animal species underlies most ecological and evolutionary processes shaping local‐ and large‐scale patterns of biodiversity. For well over a century, climatic factors have been regarded as primary sources of natural selection on animal body size, and hypotheses such as Bergmann's rule (the increase of body size with decreasing temperature) have dominated discussions. However, evidence for consistent climatic effects, especially among ectotherms, remains equivocal. Here, we test a range of key hypotheses on climate‐driven size evolution in squamate reptiles across several spatial and phylogenetic scales. Location: Global. Time period: Extant. Major taxa studied: Squamates (lizards and snakes). Methods: We quantified the role of temperature, precipitation, seasonality and net primary productivity as drivers of body mass across ca. 95% of extant squamate species (9,733 spp.). We ran spatial autoregressive models of phylogenetically corrected median mass per equal‐area grid cell. We ran models globally, across separate continents and for major squamate clades independently. We also performed species‐level analyses using phylogenetic generalized least square models and linear regressions of independent contrasts of sister species. Results: Our analyses failed to identify consistent spatial patterns in body size as a function of our climatic predictors. Nearly all continent‐ and family‐level models differed from one another, and species‐level models had low explanatory power. Main conclusions: The global distribution of body mass among living squamates varies independently from the variation in multiple components of climate. Our study, the largest in spatial and taxonomic scale conducted to date, reveals that there is little support for a universal, consistent mechanism of climate‐driven size evolution within squamates. [ABSTRACT FROM AUTHOR]

Animal lifespan is determined by extrinsic and intrinsic factors causing mortality. According to the evolutionary theories of senescence, when mortality pressures are low, animals delay reproduction. This enables species to grow more slowly and, consequently, natural selection can act against harmful mutations in adulthood, thereby increasing lifespans. To test predictions of these theories we assembled a dataset on the maximum longevities and relevant ecological variables of 1320 reptilian species. Correcting for phylogeny, we modelled the link between reptile longevity and factors such as body size, microhabitat, activity period, insularity, annual temperature, temperature seasonality, elevation and clutch size that we hypothesized will affect extrinsic mortality rates and hence lifespan. Body mass explained a small proportion of the variance in reptile longevity. Species living on islands, and in colder and more seasonal environments, lived longer. Observed maximum longevity was positively associated with the number of individuals used to estimate it. Our results suggest that species exposed to reduced extrinsic and intrinsic mortality pressures (lower predation, lower metabolic rates and shorter activity periods) live longer. Sampling more individuals increases the chances of finding older specimens and should be corrected for when studying maximum longevity. [ABSTRACT FROM AUTHOR]

Vertebrate sex-determining mechanisms ( SDMs) are triggered by the genotype ( GSD), by temperature ( TSD), or occasionally, by both. The causes and consequences of SDM diversity remain enigmatic. Theory predicts SDM effects on species diversification, and life-span effects on SDM evolutionary turnover. Yet, evidence is conflicting in clades with labile SDMs, such as reptiles. Here, we investigate whether SDM is associated with diversification in turtles and lizards, and whether alterative factors, such as lifespan's effect on transition rates, could explain the relative prevalence of SDMs in turtles and lizards (including and excluding snakes). We assembled a comprehensive dataset of SDM states for squamates and turtles and leveraged large phylogenies for these two groups. We found no evidence that SDMs affect turtle, squamate, or lizard diversification. However, SDM transition rates differ between groups. In lizards TSD-to- GSD surpass GSD-to- TSD transitions, explaining the predominance of GSD lizards in nature. SDM transitions are fewer in turtles and the rates are similar to each other ( TSD-to- GSD equals GSD-to- TSD), which, coupled with TSD ancestry, could explain TSD's predominance in turtles. These contrasting patterns can be explained by differences in life history. Namely, our data support the notion that in general, shorter lizard lifespan renders TSD detrimental favoring GSD evolution in squamates, whereas turtle longevity permits TSD retention. Thus, based on the macro-evolutionary evidence we uncovered, we hypothesize that turtles and lizards followed different evolutionary trajectories with respect to SDM, likely mediated by differences in lifespan. Combined, our findings revealed a complex evolutionary interplay between SDMs and life histories that warrants further research that should make use of expanded datasets on unexamined taxa to enable more conclusive analyses. [ABSTRACT FROM AUTHOR]

This study tries to unveil the contribution of climatic shift in shaping the extreme body size diversity in terrestrial isopods (Oniscidea). Trying to explain size variation at an interspecific level, we test five hypotheses: (1) Bergmann's Rule and the temperature-size rule postulate large size in cold areas; (2) The metabolic cold adaptation theory postulates small animal sizes in cold environments; (3) The primary productivity hypothesis predicts size increase in resource-rich areas; (4) The aridity resistance hypothesis predicts large size in arid regions; and (5). The acidosis hypothesis predicts smaller size with decreasing soil pH. Globally, Bergmann's rule and the aridity hypothesis are weakly supported. Among families and genera, results are variable and idiosyncratic. Conglobating species sizes provide weak support for the acidosis hypothesis. Overall, size is strongly affected by familial affiliation. Isopod size evolution seems to be mainly affected by phylogenetically constrained life-history traits. [ABSTRACT FROM AUTHOR]

Maayan Hahinuch Hatorani is a Haredi (ultra-Orthodox) educational network for elementary aged children in Israel, founded by Shas, a Sephardi ultra-Orthodox political party. The network's beginnings were in the second half of the 1980s, during the Shas' first Knesset term. It then consisted of around 30 smallTalmudei Torah(Haredi elementary schools for boys), set up independently by Sephardi Haredi educational activists. This article describes their motives and activities in establishing schools for the Mizrahi community and explains the decisive contribution of two additional factors to the establishment of Maayan Hahinuch Hatorani: the senior Sephardi rabbis who awarded religious legitimacy, and the Shas Movement which provided political and financial support. [ABSTRACT FROM AUTHOR]

Body size and body shape are tightly related to an animal's physiology, ecology and life history, and, as such, play a major role in understanding ecological and evolutionary phenomena. Because organisms have different shapes, only a uniform proxy of size, such as mass, may be suitable for comparisons between taxa. Unfortunately, snake masses are rarely reported in the literature. On the basis of 423 species of snakes in 10 families, we developed clade-specific equations for the estimation of snake masses from snout-vent lengths and total lengths. We found that snout-vent lengths predict masses better than total lengths. By examining the effects of phylogeny, as well as ecological and life history traits on the relationship between mass and length, we found that viviparous species are heavier than oviparous species, and diurnal species are heavier than nocturnal species. Furthermore, microhabitat preferences profoundly influence body shape: arboreal snakes are lighter than terrestrial snakes, whereas aquatic snakes are heavier than terrestrial snakes of a similar length. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ●●, ●●-●●. [ABSTRACT FROM AUTHOR]

The article discusses the ethnic religious politics in Israel in reference to the Shas Party, an ultra-orthodox religious political party in Israel. It informs that the party was founded by ultra-Orthodox rabbis, second generation Jewish immigrants from the Arab countries. It mentions the reasons for the success of the political party and mentions that the Shas Movement began in Jerusalem in 1983. It informs that the strength of Shah Movements lies with the citizens who are culturally, religiously and economically inferior. It reflects the reasons for the political organization of second-generation immigrants from Arab countries.

The article discusses the impact of mysticism, charismatic and religious leadership. It informs that the non-establishment religious leaders do not exhibit any special qualities before their revelation as demonstrated by the case of miracle worker Yaakov Ifargan. It states that there is a tension within Judaism between orthodoxy and the revitalization of ritual. As the case of Ifargan is considered, he succeeded in establishing his leadership through the non-innovative image as do other non-establishment charismatic leaders. It is believed that the creation of a community of believers is a second element of nonestablishment religious leadership.

Abstract: Aims: Central nervous system complications including cognitive impairment are an early manifestation of diabetes mellitus, also evident in animal models. NAP (generic name, davunetide), a neuroprotective peptide was tested here for its ability to prevent diabetes-related brain pathologies in the streptozotocin injected diabetes rat model. Methods: Diabetes was induced by an intraperitoneal streptozotocin injection (55mg/kg). Intranasal NAP or vehicle was administered daily starting on the day following streptozotocin injection. Cognitive assessment was performed 12weeks after diabetes induction, using the Morris water maze paradigm. Brain structural integrity was assessed on the 15th week of diabetes by magnetic resonance T2 scan. Characterization of cellular populations, apoptosis and synaptic density was performed 16weeks after diabetes induction, using immunohistochemical markers and quantified in the prefrontal cortex, the cerebral cortex and the hippocampus of both hemispheres. Results: Impaired spatial memory of the diabetic rats was observed in the water maze by attenuated learning curve and worsened performance in the probe memory test. NAP treatment significantly improved both measurements. T2 magnetic resonance imaging revealed atrophy in the prefrontal cortex of the diabetes rat group, which was prevented by NAP treatment. Immunohistochemical analysis showed that NAP treatment protected against major loss of the synaptic marker synaptophysin and astrocytic apoptosis, resulting from streptozotocin treatment. Conclusions: Our results show for the first time protective effects for NAP (davuentide) in a diabetes rat model at the behavioral and structural levels against one of the most severe complications of diabetes. [Copyright &y& Elsevier]

Abstract: The protein CsaA has been proposed to function as a protein secretion chaperone in bacteria that lack the Sec-dependent protein-targeting chaperone SecB. CsaA is a homodimer with two putative substrate-binding pockets, one in each monomer. To test the hypothesis that these cavities are indeed substrate-binding sites able to interact with other polypeptide chains, we selected a peptide that bound to CsaA from a random peptide library displayed on phage. Presented here is the structure of CsaA from Agrobacterium tumefaciens (AtCsaA) solved in the presence and absence of the selected peptide. To promote co-crystallization, the sequence for this peptide was genetically fused to the amino-terminus of AtCsaA. The resulting 1.65 Å resolution crystal structure reveals that the tethered peptide from one AtCsaA molecule binds to the proposed substrate-binding pocket of a symmetry-related molecule possibly mimicking the interaction between a pre-protein substrate and CsaA. The structure shows that the peptide lies in an extended conformation with alanine, proline and glutamine side chains pointing into the binding pocket. The peptide interacts with the atoms of the AtCsaA-binding pocket via seven direct hydrogen bonds. The side chain of a conserved pocket residue, Arg76, has an “up” conformation when the CsaA-binding site is empty and a “down” conformation when the CsaA-binding site is occupied, suggesting that this residue may function to stabilize the peptide in the binding cavity. The presented aggregation assays, phage-display analysis and structural analysis are consistent with AtCsaA being a general chaperone. The properties of the proposed CsaA-binding pocket/peptide interactions are compared to those from other structurally characterized molecular chaperones. [Copyright &y& Elsevier]

Infectious pancreatic necrosis virus (IPNV), an aquatic birnavirus that infects salmonid fish, encodes a large polyprotein (NH2-pVP2-VP4-VP3-COOH) that is processed through the proteolytic activity of its own protease, VP4, to release the proteins pVP2 and VP3. pVP2 is further processed to give rise to the capsid protein VP2 and three peptides that are incorporated into the virion. Reported here are two crystal structures of the IPNV VP4 protease solved from two different crystal symmetries. The electron density at the active site in the triclinic crystal form, refined to 2.2-Å resolution, reveals the acyl-enzyme complex formed with an internal VP4 cleavage site. The complex was generated using a truncated enzyme in which the general base lysine was substituted. Inside the complex, the nucleophilic Ser633Oγ forms an ester bond with the main-chain carbonyl of the C-terminal residue, Ala716, of a neighboring VP4. The structure of this substrate-VP4 complex allows us to identify the S1, S3, S5, and S6 substrate binding pockets as well as other substrate-VP4 interactions and therefore provides structural insights into the substrate specificity of this enzyme. The structure from the hexagonal crystal form, refined to 2.3-Å resolution, reveals the free-binding site of the protease. Three-dimensional alignment with the VP4 of blotched snakehead virus, another birnavirus, shows that the overall structure of VP4 is conserved despite a low level of sequence identity (∼19%). The structure determinations of IPNV VP4, the first of an acyl-enzyme complex for a Ser/Lys dyad protease, provide insights into the catalytic mechanism and substrate recognition of this type of protease. [ABSTRACT FROM AUTHOR]

In viruses belonging to the Birnaviridae family, virus protein 4 (VP4) is the viral protease responsible for the proteolytic maturation of the polyprotein encoding the major capsid proteins (VP2 and VP3). Infectious pancreatic necrosis virus (IPNV), the prototype of the aquabirnavirus genus, is the causative agent of a contagious disease in fish which has a large economic impact on aquaculture. IPNV VP4 is a 226-residue (24.0 kDa) serine protease that utilizes a Ser/Lys catalytic dyad mechanism (Ser633 and Lys674). Several truncated and mutant forms of VP4 were expressed in a recombinant expression system, purified and screened for crystallization. Two different crystal forms diffract beyond 2.4 Å resolution. A triclinic crystal derived from one mutant construct has unit-cell parameters a = 41.7, b = 69.6, c = 191.6 Å, α = 93.0, β = 95.1, γ = 97.7°. A hexagonal crystal with space group P6122/ P6522 derived from another mutant construct has unit-cell parameters a = 77.4, b = 77.4, c = 136.9 Å. [ABSTRACT FROM AUTHOR]

The blotched snakehead virus (BSNV), an aquatic birnavirus, encodes a polyprotein (NH2-pVP2-X-VP4-VP3-COOH) that is processed through the proteolytic activity of its own protease (VP4) to liberate itself and the viral proteins pVP2, X and VP3. The protein pVP2 is further processed by VP4 to give rise to the capsid protein VP2 and four structural peptides. We report here the crystal structure of a VP4 protease from BSNV, which displays a catalytic serine/lysine dyad in its active site. This is the first crystal structure of a birnavirus protease and the first crystal structure of a viral protease that utilizes a lysine general base in its catalytic mechanism. The topology of the VP4 substrate binding site is consistent with the enzymes substrate specificity and a nucleophilic attack from the si-face of the substrates scissile bond. Despite low levels of sequence identity, VP4 shows similarities in its active site to other characterized Ser/Lys proteases such as signal peptidase, LexA protease and Lon protease. Together, the structure of VP4 provides insights into the mechanism of a recently characterized clan of serine proteases that utilize a lysine general base and reveals the structure of potential targets for antiviral therapy, especially for other related and economically important viruses, such as infectious bursal disease virus in poultry and infectious pancreatic necrosis virus in aquaculture. [Copyright &y& Elsevier]

Blotched snakehead virus (BSNV) is a member of the Birnaviridae family that requires a virally encoded protease known as VP4 in order to process its polyprotein into viral capsid protein precursors (pVP2 and VP3). VP4 belongs to a family of serine proteases that utilize a serine/lysine catalytic dyad mechanism. A mutant construct of VP4 with a short C-terminal truncation was overexpressed in Escherichia coli and purified to homogeneity for crystallization. Using the sitting-drop vapour-diffusion method at room temperature, protein crystals with two distinct morphologies were observed. Cubic crystals grown in PEG 2000 MME and magnesium acetate at pH 8.5 belong to space group I23, with unit-cell parameters a = b = c = 143.8 Å. Trigonal crystals grown in ammonium sulfate and glycerol at pH 8.5 belong to space group P321/ P312, with unit-cell parameters a =  b = 158.2, c = 126.4 Å. [ABSTRACT FROM AUTHOR]

The current study examined trends regarding religion and spirituality among Jewish and Bedouin female students studying education and sciences at Achva Academic College, a rural secular college in southern Israel. The Bedouin women all originated from an isolationist traditional society, vigilantly maintained over many years. Contrastingly, the Jewish women come from a secular or traditional society, which is not isolationist. Science and education are two completely different worlds of content. Science studies include analytical research, with the students carrying out experiments in laboratories and within the community, whereas education studies focus on pedagogy and transfer of knowledge. The study employed a questionnaire with Likert items regarding religion and spirituality. We found the Bedouin students were more religious than the Jewish ones, but spirituality levels were similar. This finding indicated that the Bedouin students have indeed broken down the barriers to academic education, but still have retained their traditional community framework. Likewise, we found that the students of science were less observant of religious practices in comparison to those studying education, but they were similar regarding spirituality and the theoretical aspects of religion. This finding showed that practical aspects of religion can be a factor influencing the choice of field of study. [ABSTRACT FROM AUTHOR]

We describe the finding, in a museum jar, of the sixth known specimen of the Eritrean snake Platyceps largeni (Scätti, 2001) (synonym, Coluber largeni). The specimen is from Museri Island, Dahlak Archipelago in the Red Sea. This record is the first one for this island and it represents a ca. 50 km range extension of this species, hitherto known from five specimens in a tight cluster of three other islands. This find verifies Schätti's (2001) prediction that the species might be found in the nearby archipelago islands. [ABSTRACT FROM AUTHOR]

Modern conservation operates at the nexus of biological and social influences. While the importance of social and cultural factors is often mentioned, defining, measuring and comparing these factors remains a significant challenge. Here, we explore a novel method to quantify cultural interest in all extant reptile species using Wikipedia — a large, open-access online encyclopaedia. We analysed all page views of reptile species viewed during 2014 in all of Wikipedia's language editions. We compared species' page view numbers across languages and in relationship to their spatial distribution, phylogeny, threat status and various other biological attributes. We found that the three species with most page views are shared across major language editions, beyond these, page view ranks of species tend to be specific to particular language editions. Interest within a language is mostly focused on reptiles found in the regions where the language is spoken. Overall, interest is greater for reptiles that are venomous, endangered, widely distributed, larger and that have been described earlier. However, within individual reptile families not all the above factors predict page views. Most families contain at least one species in the top 5% of page views, but 29 families (with 1,450 species) have no ‘high interest species’ in them. Overall, our analyses elucidate novel patterns of human interests in nature over large geographical, cultural and taxonomic spectra using big-data techniques. Such approaches hold much promise for incorporating social perceptions in future conservation practices. [ABSTRACT FROM AUTHOR]

[This corrects the article DOI: 10.1002/ece3.2277.].

Infectious pancreatic necrosis virus (IPNV), an aquatic birnavirus that infects salmonid fish, encodes a large polyprotein (NH(2)-pVP2-VP4-VP3-COOH) that is processed through the proteolytic activity of its own protease, VP4, to release the proteins pVP2 and VP3. pVP2 is further processed to give rise to the capsid protein VP2 and three peptides that are incorporated into the virion. Reported here are two crystal structures of the IPNV VP4 protease solved from two different crystal symmetries. The electron density at the active site in the triclinic crystal form, refined to 2.2-A resolution, reveals the acyl-enzyme complex formed with an internal VP4 cleavage site. The complex was generated using a truncated enzyme in which the general base lysine was substituted. Inside the complex, the nucleophilic Ser(633)Ogamma forms an ester bond with the main-chain carbonyl of the C-terminal residue, Ala(716), of a neighboring VP4. The structure of this substrate-VP4 complex allows us to identify the S1, S3, S5, and S6 substrate binding pockets as well as other substrate-VP4 interactions and therefore provides structural insights into the substrate specificity of this enzyme. The structure from the hexagonal crystal form, refined to 2.3-A resolution, reveals the free-binding site of the protease. Three-dimensional alignment with the VP4 of blotched snakehead virus, another birnavirus, shows that the overall structure of VP4 is conserved despite a low level of sequence identity ( approximately 19%). The structure determinations of IPNV VP4, the first of an acyl-enzyme complex for a Ser/Lys dyad protease, provide insights into the catalytic mechanism and substrate recognition of this type of protease.

In viruses belonging to the Birnaviridae family, virus protein 4 (VP4) is the viral protease responsible for the proteolytic maturation of the polyprotein encoding the major capsid proteins (VP2 and VP3). Infectious pancreatic necrosis virus (IPNV), the prototype of the aquabirnavirus genus, is the causative agent of a contagious disease in fish which has a large economic impact on aquaculture. IPNV VP4 is a 226-residue (24.0 kDa) serine protease that utilizes a Ser/Lys catalytic dyad mechanism (Ser633 and Lys674). Several truncated and mutant forms of VP4 were expressed in a recombinant expression system, purified and screened for crystallization. Two different crystal forms diffract beyond 2.4 A resolution. A triclinic crystal derived from one mutant construct has unit-cell parameters a = 41.7, b = 69.6, c = 191.6 A, alpha = 93.0, beta = 95.1, gamma = 97.7 degrees. A hexagonal crystal with space group P6(1)22/P6(5)22 derived from another mutant construct has unit-cell parameters a = 77.4, b = 77.4, c = 136.9 A.