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The liver is important in the synthesis, metabolism and storage of nutrients, detoxification and immune response of the body, and the liver immune response against exogenous pathogens from the intestinal tract plays a key role in the immune activities. However, the cellular composition of the liver immune atlas remains sparsely studied in reptiles. We used single-cell RNA sequencing to identify the cellular profile of the liver of the Chinese soft-shelled turtle (Pelodiscus sinensis). We obtained the transcriptional landscape based on 9938 cells from the fractionation of fresh hepatic tissues from two individuals, uninfected and infected with bacteria (Aeromonas hydrophila). We identified seven hepatic immune cell subsets, including plasma, erythroid, T/NK, B, endothelial, dendritic and Kupffer cells. Bacteria-infection altered the number of liver immune cells, as revealed by the fact that the infected turtle had more plasma, endothelial and Kupffer cells and fewer T/NK, dendritic and erythroid cells than did the uninfected turtle. Our study is the first to provide a comprehensive view of the hepatic immune landscape of P. sinensis at the single-cell resolution that outlines the characteristics of immune cells in the turtle liver and provides a liver transcriptome baseline for turtle immunology.

We used Takydromus septentrionalis, a sexually size-monomorphic lacertid lizard, as a model system to test the hypothesis that sexual size monomorphism may evolve in lizards where reproductive performance is maximized at a similar body size for both sexes. We allowed lizards housed in laboratory enclosures to lay as many clutches (for females) as they could or to mate as many times (for males) as they could in a breeding season. Size-assortative mating was weak but evident in T. septentrionalis, as revealed by the fact that male and female snout–vent lengths (SVLs) in mating pairs were significantly and positively correlated. Mating frequency (indicative of male reproductive performance) varied from 1 to 8 per breeding season, generally increasing as SVL increased in adult males smaller than 67.4 mm SVL. Clutch frequency varied from 1 to 7 per breeding season, with female reproductive performance (determined by clutch frequency, annual fecundity, and annual reproductive output) maximized in females with a SVL of 68.0 mm. Accordingly to our hypothesis, the reproductive performance was maximized in the intermediate sized rather than the largest individuals in both sexes, and the body size maximizing reproductive performance was similar for both sexes. Future work could usefully investigate other lineages of lizards with sexually monomorphic species in a phylogenetic context to corroborate the hypothesis of this study.

In the era of intensity-modulated radiotherapy (IMRT), it is important to analyse the prognostic value of deficient mismatch repair (dMMR) in nasopharyngeal carcinoma (NPC). In this study, in pretreatment biopsies of 69 patients with stage II–IVa NPC, the expression levels of MMR proteins, including MLH1, MSH2, MSH6 and PMS2, were assessed by immunohistochemistry (IHC). The median follow-up time was 37.5 months (3.1–87.4 months). 50.7% of cases (35/69) showed preserved expression of all 4 MMR proteins, which was interpreted as proficient mismatch repair (pMMR). Only 1.5% of cases (1/69) lost expression of all 4 MMR proteins, 26.1% of cases (18/69) have PMS2 loss alone and 21.7% of cases (15/69) lost expression of both PMS2 and MLH1. Thus, 49.3% of cases (34/69) lost expression of one or more MMR proteins, which was interpreted as dMMR. There was no significant difference (P > 0.05) in terms of sex, age, clinical stage, T category, N category or therapy regimens between the dMMR and pMMR groups. The multivariate Cox regression analysis revealed that dMMR was an independent significant prognostic factor for distant metastasis-free survival (DMFS) (dMMR vs pMMR: P = 0.01, HR = 0.25, 95% CI: 0.09~0.75). Therefore, NPC patients with dMMR had significantly superior DMFS compared with patients with pMMR. It can be expected that dMMR will become a new independent prognostic factor for NPC.

Monitor lizards (Varanidae) inhabit both the mainland and islands of all geological types and have diversified into an exceptionally wide range of body sizes, thus providing an ideal model for examining the role of mainland versus island in driving species evolution. Here we use phylogenetic comparative methods to examine whether a link exists between body size-driven diversification and body size-frequency distributions in varanid lizards and to test the hypothesis that island lizards differ from mainland species in evolutionary processes, body size, and life-history traits (offspring number and size). We predict that: 1) since body size drives rapid diversification in groups, a link exists between body size-driven diversification and body size-frequency distributions; 2) because of various environments on island, island species will have higher speciation, extinction, and dispersal rates, compared with mainland species; 3) as a response to stronger intraspecific competition, island species will maximize individual ability associated with body size to outcompete closely-related species, and island species will produce smaller clutches of larger eggs to increase offspring quality. Our results confirm that the joint effect of differential macroevolutionary rates shapes the species richness pattern of varanid lizards. There is a link between body size-driven diversification and body size-frequency distributions, and the speciation rate is maximized at medium body sizes. Island species will have higher speciation, equal extinction, and higher dispersal rates compared with mainland species. Smaller clutch size and larger hatchling in the island than in mainland species indicate that offspring quality is more valuable than offspring quantity for island varanids.

Given that the venom system in sea snakes has a role in enhancing their secondary adaption to the marine environment, it follows that elucidating the diversity and function of venom toxins will help to understand the adaptive radiation of sea snakes. We performed proteomic and de novo NGS analyses to explore the diversity of venom toxins in the annulated sea snake (Hydrophis cyanocinctus) and estimated the adaptive molecular evolution of the toxin-coding unigenes and the toxicity of the major components. We found three-finger toxins (3-FTxs), phospholipase A2 (PLA2) and cysteine-rich secretory protein (CRISP) in the venom proteome and 59 toxin-coding unigenes belonging to 24 protein families in the venom-gland transcriptome, 3-FTx and PLA2 were the most abundant families. Nearly half of the toxin-coding unigenes had undergone positive selection. The short- (i.p. 0.09 μg/g) and long-chain neurotoxin (i.p. 0.14 μg/g) presented fairly high toxicity, whereas both basic and acidic PLA2s expressed low toxicity. The toxicity of H. cyanocinctus venom was largely determined by the 3-FTxs. Our data show the venom is used by H. cyanocinctus as a biochemically simple but genetically complex weapon and venom evolution in H. cyanocinctus is presumably driven by natural selection to deal with fast-moving prey and enemies in the marine environment.

This paper mainly focuses on the strong convergence of the Euler-Maruyama method for nonlinear stochastic convolution Ito-Volterra integral equations with constant delay. It is well known that the strong approximation of the Ito integral usually leads to 0.5-order approximation for stochastic problems. However, in this paper, we will show that 1-order strong superconvergence can be obtained for nonlinear stochastic convolution Ito-Volterra integral equations with constant delay under some mild conditions on the kernel of the diffusion term. Finally, some numerical experiments are given to illustrate our theoretical results.

Background A comprehensive evaluation of the -omic profiles of venom is important for understanding the potential function and evolution of snake venom. Here, we conducted an integrated multi-omics-analysis to unveil the venom-transcriptomic and venomic profiles in a same group of spine-bellied sea snakes (Hydrophis curtus) from the South China Sea, where the snake is a widespread species and might generate regionally-specific venom potentially harmful to human activities. The capacity of two heterologous antivenoms to immunocapture the H. curtus venom was determined for an in-depth evaluation of their rationality in treatment of H. curtus envenomation. In addition, a phylogenetic analysis by maximum likelihood was used to detect the adaptive molecular evolution of full-length toxin-coding unigenes. Results A total of 90,909,384 pairs of clean reads were generated via Illumina sequencing from a pooled cDNA library of six specimens, and yielding 148,121 unigenes through de novo assembly. Sequence similarity searching harvested 63,845 valid annotations, including 63,789 non-toxin-coding and 56 toxin-coding unigenes belonging to 22 protein families. Three protein families, three-finger toxins (3-FTx), phospholipase A2 (PLA2), and cysteine-rich secretory protein, were detected in the venom proteome. 3-FTx (27.15% in the transcriptome/41.94% in the proteome) and PLA2 (59.71%/49.36%) were identified as the most abundant families in the venom-gland transcriptome and venom proteome. In addition, 24 unigenes from 11 protein families were shown to have experienced positive selection in their evolutionary history, whereas four were relatively conserved throughout evolution. Commercial Naja atra antivenom exhibited a stronger capacity than Bungarus multicinctus antivenom to immunocapture H. curtus venom components, especially short neurotoxins, with the capacity of both antivenoms to immunocapture short neurotoxins being weaker than that for PLA2s. Conclusions Our study clarified the venom-gland transcriptomic and venomic profiles along with the within-group divergence of a H. curtus population from the South China Sea. Adaptive evolution of most venom components driven by natural selection appeared to occur rapidly during evolutionary history. Notably, the utility of commercial N. atra and B. multicinctus antivenoms against H. curtus toxins was not comprehensive; thus, the development of species-specific antivenom is urgently needed.

In recent years, the obese and overweight population has increased rapidly, which has become a worldwide public health problem. However, effective medication is lacking. Our previous study identified a novel peptide, PDBSN (GLSVADLAESIMKNL), that could significantly restrict adipocyte differentiation in vitro, but its in vivo function has not been determined. Thus, in this study, we encapsulated the peptide into liposomes attached with two ligands (visceral-adipose-tissue-targeting peptide and cell-penetrating peptide) to improve stability and specificity. We then tested the peptide’s function in HFD (high-fat diet)-induced obese mice and found that PDBSN could reduce weight gain and improve insulin resistance as well as lipid homeostasis. These results suggest that PDBSN may be a potential candidate for anti-obesity drug discovery.

We conducted an omics-analysis of the venom of Naja kaouthia from China. Proteomics analysis revealed six protein families [three-finger toxins (3-FTx), phospholipase A2 (PLA2), nerve growth factor, snake venom metalloproteinase (SVMP), cysteine-rich secretory protein and ohanin], and venom-gland transcriptomics analysis revealed 28 protein families from 79 unigenes. 3-FTx (56.5% in proteome/82.0% in transcriptome) and PLA2 (26.9%/13.6%) were identified as the most abundant families in venom proteome and venom-gland transcriptome. Furthermore, N. kaouthia venom expressed strong lethality (i.p. LD50: 0.79 μg/g) and myotoxicity (CK: 5939 U/l) in mice, and showed notable activity in PLA2 but weak activity in SVMP, l -amino acid oxidase or 5′ nucleotidase. Antivenomic assessment revealed that several venom components (nearly 17.5% of total venom) from N. kaouthia could not be thoroughly immunocaptured by commercial Naja atra antivenom. ELISA analysis revealed that there was no difference in the cross-reaction between N. kaouthia and N. atra venoms against the N. atra antivenom. The use of commercial N. atra antivenom in treatment of snakebites caused by N. kaouthia is reasonable, but design of novel antivenom with the attention on enhancing the immune response of non-immunocaptured components should be encouraged. Biological significance The venomics, antivenomics and venom-gland transcriptome of the monocoled cobra (Naja kaouthia) from China have been elucidated. Quantitative and qualitative differences are evident when venom proteomic and venom-gland transcriptomic profiles are compared. Two protein families (3-FTx and PLA2) are found to be the predominated components in N. kaouthia venom, and considered as the major players in functional role of venom. Other protein families with relatively low abundance appear to be minor in the functional significance. Antivenomics and ELISA evaluation reveal that the N. kaouthia venom can be effectively immunorecognized by commercial N. atra antivenom, but still a small number of venom components could not be thoroughly immunocaptured. The findings indicate that exploring the precise composition of snake venom should be executed by an integrated omics-approach, and elucidating the venom composition is helpful in understanding composition-function relationships and will facilitate the clinical application of antivenoms.

Background The oviparity-viviparity transition is a major evolutionary event, likely altering the reproductive process of the organisms involved. Residual yolk, a portion of yolk remaining unutilized at hatching or birth as parental investment in care, has been investigated in many oviparous amniotes but remained largely unknown in viviparous species. Here, we used data from 20 (12 oviparous and 8 viviparous) species of snakes to see if the oviparity-viviparity transition alters the partitioning of yolk in embryonic snakes. We used ANCOVA to test whether offspring size, mass and components at hatching or birth differed between the sexes in each species. We used both ordinary least squares and phylogenetic generalized least squares regressions to test whether relationships between selected pairs of offspring components were significant. We used phylogenetic ANOVA to test whether offspring components differed between oviparous and viviparous species and, more specifically, the hypothesis that viviparous snakes invest more in the yolk as parental investment in embryogenesis to produce more well developed offspring that are larger in linear size. Results In none of the 20 species was sex a significant source of variation in any offspring component examined. Newborn viviparous snakes on average contained proportionally more water and, after accounting for body dry mass, had larger carcasses but smaller residual yolks than did newly hatched oviparous snakes. The rates at which carcass dry mass (CDM) and fat body dry mass (FDM) increased with residual yolk dry mass (YDM) did not differ between newborn oviparous and viviparous snakes. Neither CDM nor FDM differed between newborn oviparous and viviparous snakes after accounting for YDM. Conclusions Our results are not consistent with the hypothesis that the partitioning of yolk between embryonic and post-embryonic stages differs between snakes that differ in parity mode, but instead show that the partitioning of yolk in embryonic snakes is species-specific or phylogenetically related. We conclude that the oviparity-viviparity transition does not alter yolk partitioning in embryonic snakes. Electronic supplementary material The online version of this article (10.1186/s12862-017-1083-z) contains supplementary material, which is available to authorized users.

We conducted an in-depth analysis of the proteomic and biochemical profiles of the venom of neonate and adult short-tailed pit vipers ( Gloydius brevicaudus ). Identified proteins were assigned to a few main toxin families. Disintegrin, phospholipase A 2 (PLA 2 ), serine proteinase, cysteine-rich secretory protein, C-type lectin-like protein, l -amino acid oxidase and snake venom metalloproteinase (SVMP) were detected in both venoms, while 5′-nucleotidase was detected only in the adult venom. SVMP was the predominant protein family in both venoms (neonate: 65.7%; adult: 64.4%), followed by PLA 2 (neonate: 13.4%; adult: 25.0%). Antivenomic analysis revealed that commercial G. brevicaudus antivenom almost neutralized the chromatographic peaks with medium and high molecular masses in both venoms, but did not completely recognize peaks with low molecular mass. Toxicological and enzymatic activities show remarkable age-related variation in G. brevicaudus venom, probably resulting from variation in venom composition. Our data demonstrate age-related variation across venomics, antivenomics and biochemical profiles of G. brevicaudus venom, and have implications for the management of G. brevicaudus bites, including improving antivenom preparation by combining both venoms. Biological significance This study investigates the composition and biochemical activity of neonate and adult Gloydius brevicaudus venoms. We found remarkable age-related variation in venom biological activity, likely the result of variation in venom composition. Antivenomics analysis was used to explore difference in neonate and adult G. brevicaudus venoms. Our findings have implications for the diagnosis and clinical management of G. brevicaudus bites, and the design of venom mixtures that will increase the efficacy of commercial antivenom. This article is part of a Special Issue entitled: Proteomics of non-model organisms.

Snake venoms undergo ontogenetic shifts in biochemical and pharmacological activities. This may be related to variation in venom components associated with the ontogenetic shift in diet. We used the short-tailed pit viper Gloydius brevicaudus that displays ontogenetic shifts in diet to examine whether the species displays a neonate-to-adult transition of snake venomics. Venoms from neonates and adults were pooled separately and then analyzed by 2-DE, MALDI-TOF-MS/MS and iTRAQ technologies. The 2-DE profiles showed that the main components in both types of venoms were acidic proteins, and that neonates and adults differed in snake venomics. The proteins with molecular masses/pI of ~ 12–39 kDa/4.0–4.6, ~ 36–57 kDa/5.6–7.0 and ~ 65–92 kDa/4.5–5.8 were more abundant in the neonate venom, while the proteins with molecular masses/pI of ~ 12–19 kDa/4.6–6.4, ~ 23–30 kDa/5.4–6.3 and ~ 35–62 kDa/4.6–5.4 were more abundant in the adult venom. The iTRAQ analysis showed quantitative changes in various toxin families, including mainly metalloproteinases, serine proteinases, phospholipase A 2 s and C-type lectins. The N -deglycosylation analysis demonstrated that glycosylation was an important post-translational modification of snake venom. Our results show a neonate-to-adult transition of snake venomics in G. brevicaudus . Such a transition might be driven by the divergence in dietary habits between neonates and adults. Biological significance This study is first to demonstrate a neonate-to-adult transition of snake venomics in G. brevicaudus , and the results will be helpful in predicting and treating clinical pathologic symptoms caused by the snake at different developmental stages.

We studied the immunoreactivity between venoms and commercial antiserums in four Chinese venomous snakes, Bungarus multicinctus, Naja atra, Deinagkistrodon acutus and Gloydius brevicaudus. Venoms from the four snakes shared common antigenic components, and most venom components expressed antigenicity in the immunological reaction between venoms and antiserums. Antiserums cross-reacted with heterologous venoms. Homologous venom and antiserum expressed the highest reaction activity in all cross-reactions. Species-specific antibodies (SSAbs) were obtained from four antiserums by immunoaffinity chromatography: the whole antiserum against each species was gradually passed through a medium system coated with heterologous venoms, and the cross-reacting components in antiserum were immunoabsorbed by the common antigens in heterologous venoms; the unbound components (i.e., SSAbs) were collected, and passed through Hitrap G protein column and concentrated. The SSAbs were found to have high specificity by western blot and enzyme-linked immunosorbent assay (ELISA). A 6-well ELISA strip coated with SSAbs was used to assign a venom sample and blood and urine samples from the envenomed rats to a given snake species. Our detections could differentiate positive and negative samples, and identify venoms of a snake species in about 35 min. The ELISA strips developed in this study are clinically useful in rapid and reliable identification of venoms from the above four snake species.

We characterize 25 polymorphic microsatellite loci isolated from Leiolepis reevesii genomic libraries. Thirty-four individuals were collected from two populations, eighteen from a mainland population in Xuwen, Guangdong, and the remaining 16 from an island population in Haikou, Hainan. These markers revealed a relatively high degree of genetic diversity (2–18 alleles per locus) and heterozygosity (H O ranged from 0.000–0.938, and H E ranged from 0.160–0.954). Eight loci exhibited significant deviations from Hardy–Weinberg equilibrium (HWE) after sequential Bonferroni correction due to heterozygote deficiencies, but only one locus (L311) with low heterozygosity in one population did significantly deviate from HWE in the other. Inbreeding may explain the deviations from HWE. There was no evidence of linkage disequilibrium among pairs of loci in the samples. These microsatellite markers will be useful for future studies focusing on gene flow, population structure and evolutionary history of L. reevesii.

701..709 We collected gravid king ratsnakes (Elaphe carinata) from three geographically separated populations in Chenzhou (CZ), Lishui (LS) and Dinghai (DH) of China to study the geographical variation in female reproductive traits and trade-offs between the size and number of eggs. Not all reproductive traits varied among the three populations. Of the traits examined, five (egg-laying date, post-oviposition body mass, clutch size, egg mass and egg width) differed among the three populations. The egg-laying date, ranging from late June to early August, varied among populations in a geographically continuous trend, with females at the most northern latitude (DH) laying eggs latest, and females at the most southern latitude (CZ) laying eggs earliest. Such a trend was less evident or even absent in the other traits that differed among the three populations. CZ and DH females, although separated by a distance of approximately 1100 km as the crow flies, were similar to each other in most traits examined. LS females were distinguished from CZ and DH females by the fact that they laid a greater number of eggs, but these were smaller. The egg size-number trade-off was evident in each of the three populations and, at a given level of relative fecundity, egg mass was significantly greater in the DH population than in the LS population. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104, 701-709.

Abstract We studied sexual dimorphism and female reproduction in two sympatric species of toad-headed lizards, Phrynocephalus frontalis and P. versicolor, from Inner Mongolia, North China. The smallest reproductive females of P. frontalis and P. versicolor we recorded were 43.5 mm and 44.2 mm SVL, respectively. Females were the larger sex in P. versicolor, whereas female and male adults of P. frontalis did not differ in mean SVL. Females of P. frontalis were on average smaller than females of P. versicolor, so were males of P. frontalis. In both species females were larger in abdomen length (AL) but smaller in head length (HL), head width (HW) and tail length (TL); adults of P. frontalis were larger in HL and TL but smaller in AL and HW than adults of P. versicolor of the same size. Females of both species laid a single clutch of 2-6 eggs per breeding season. The trade-off between size and number of eggs was evident in both species. Of the examined female reproductive traits, only clutch size and egg size differed between the two species, with females of P. frontalis laying fewer but larger eggs than did females of P. versicolor of the same SVL. However, as the observed between-species difference in egg size (and thus, offspring size) was small, any niche divergence resulting from this difference could be less important in reducing competitions between these two sympatric species of lizards.

The methyl coumarins reacted with N-bromo-succinimide gave compounds (a∼c) which on further reacted with various peracetyl sulfhydryl glycose (1∼3) afforded a series of novel coumarin thioglycopyranoside compounds (1a∼1c, 2a∼2c, 3a∼3c). And when used ultrasonic irradiation, this method offered several advantages such as good yields and short reaction time than the silent reaction. All the new compounds were characterized on the basis of the IR, 1 H NMR, 13 C NMR and elemental analysis.

A series of novel thioglycoside derivatives containing 4(3H)-quinazolinone was designed and synthesized from 2-chloromethyl-quinazolin-4(3H)-ones and 1-thioglycose. Several 2-chloromethyl-quinazolin-4(3H)-ones were synthesized on refluxing with 2-(chloroacetylamino)-benzoic acid and arylamines in acetonitrile. All of the novel compounds were characterized by IR, 1 H NMR spectra and elemental analysis. The structures of compounds 7b, 8b and 8c have been determined by X-ray diffraction analysis.

Bungarus multicinctus (many-banded krait) and Naja atra (Chinese cobra) are widely distributed and medically important venomous snakes in China; however, their venom proteomic profiles have not been fully compared. Here, we fractionated crude venoms and analyzed them using a combination of proteomic techniques. Three-finger toxins (3-FTx) and phospholipase A2 (PLA2) were most abundant in both species, respectively accounting for 32.6% and 66.4% of total B. multicinctus venom, and 84.3% and 12.2% of total N. atra venom. Venoms from these two species contained one common protein family and six less abundant species-specific protein families. The proteomic profiles of B. multicinctus and N. atra venoms and analysis of toxicological activity in mice suggested that 3-FTx and PLA2 are the major contributors to clinical symptoms caused by envenomation. The venoms differed in enzymatic activity, likely the result of inter-specific variation in the amount of related venom components. Antivenomics assessment revealed that a small number of venom components (3-FTxs and PLA2s in B. multicinctus, and 3-FTxs in N. atra) could not be immunocaptured completely, suggesting that we should pay attention to enhancing the immune response of these components in designing commercial antivenoms for B. multicinctus and N. atra. Biological significance The proteomic profiles of venoms from two medically important snake species – B. multicinctus and N. atra – have been explored. Quantitative and qualitative differences are evident in both venoms when proteomic profiles and transcriptomic results are compared; this is a reminder that combined approaches are needed to explore the precise composition of snake venom. Two protein families (3-FTx and PLA2) of high abundance in these snake venoms are major players in the biochemical and pharmacological effects of envenomation. Elucidation of the proteomic profiles of these snake venoms is helpful in understanding composition-function relationships and will facilitate the clinical application of antivenoms.

Death domains (DDs) mediate assembly of oligomeric complexes for activation of downstream signaling pathways through incompletely understood mechanisms. Here we report structures of complexes formed by the DD of p75 neurotrophin receptor (p75NTR) with RhoGDI, for activation of the RhoA pathway, with caspase recruitment domain (CARD) of RIP2 kinase, for activation of the NF-kB pathway, and with itself, revealing how DD dimerization controls access of intracellular effectors to the receptor. RIP2 CARD and RhoGDI bind to p75NTR DD at partially overlapping epitopes with over 100-fold difference in affinity, revealing the mechanism by which RIP2 recruitment displaces RhoGDI upon ligand binding. The p75NTR DD forms non-covalent, low-affinity symmetric dimers in solution. The dimer interface overlaps with RIP2 CARD but not RhoGDI binding sites, supporting a model of receptor activation triggered by separation of DDs. These structures reveal how competitive protein-protein interactions orchestrate the hierarchical activation of downstream pathways in non-catalytic receptors. DOI: http://dx.doi.org/10.7554/eLife.11692.001, eLife digest Cells have proteins called receptors on their surface that can bind to specific molecules on the outside of the cell. Typically, this binding activates the receptor and the activated receptor then triggers some biochemical changes inside the cell. For many receptors, the portion of the receptor inside the cell is essentially an enzyme that can trigger a biochemical change by itself. Some receptors, however, lack any enzymatic activity, and it is often unclear how these ‘non-catalytic receptors’ trigger changes inside a cell. A protein called p75 neurotrophin receptor (or p75NTR for short) is a non-catalytic receptor that is expressed when neurons are injured and its activity leads to the death of the neurons and related cells. Inhibiting this non-catalytic receptor is an attractive strategy for limiting the damage caused by diseases of the nervous system. However, the molecular mechanisms behind the activity of p75NTR are not well understood. Previous biochemical studies set out to answer the question of how p75NTR engages with components of the signaling machinery inside the cell, and found several components that interact with this receptor. Now, Lin et al. have tried to gain a more detailed understanding of those interactions at a molecular level. This involved solving the three-dimensional structures of three protein complexes that involve part of p75NTR (called the “death domain”) and one of two signaling components (called RhoGDI and RIP2). Two of the protein complexes showed that RIP2 and RhoGDI bind to the receptor’s death domain at partially overlapping sites, although RIP2 binds about 100 times more strongly than RhoGDI.A third protein complex showed an interaction between two copies of the death domain, which involves a surface of the receptor that overlaps with RIP2’s, but not RhoGDI’s, binding site. These structures, together with the results of other experiments, allowed Lin et al. to propose a model that could explain how p75NTR is activated. First, the two death domains must be separated. Next, RIP2 is recruited to the receptor, and outcompetes and displaces RhoGDI. This change in protein-protein interactions switches the receptor’s signaling from one pathway to the other. Now that these structures are available, they can be used in future experiments to design specific changes in the receptor that would allow researchers to dissect its different activities. DOI: http://dx.doi.org/10.7554/eLife.11692.002

We maintained pregnant Sphenomorphus indicus under four thermal conditions for the whole gestation period to assess the effects of gestation temperature on offspring phenotypes. Parturition occurred between late June and early August, with females at high body temperatures giving birth earlier than those maintained at low body temperatures. Litter size, litter mass, and postpartum body mass did not differ among treatments, and females with relatively higher fecundity produced smaller offspring. Females gave birth to predominantly female offspring (85.7% of the 14 sexed offspring were females) at 24 °C and to predominantly male offspring (76.5% of the 17 sexed offspring were males) at 28 °C. Females with the opportunity to regulate body temperature produced a mix of sexes that did not differ from equality. Offspring produced in different treatments differed in head size, hind-limb length, and tympanum length, but not in snout-vent length, tail length, body mass, fore-limb length, and eye length. Offspring produced at 28 °C were not only smaller in head size, but also shorter in hind-limb length and tympanum length than those offspring produced at lower temperatures. Offspring produced at 28 °C performed more poorly in the racetrack and grew more slowly than offspring produced in the other three treatments. Taken together, our results show that S. indicus might be a temperature-dependent sex determination species and that offspring phenotypes are impaired at high gestation temperatures but maximized at relatively low gestation temperatures. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 88, 453–463.

We used 17 hatchling five-paced pit-vipers snakes (Deinagkistrodon acutus) to study within-clutch variation in snake venoms. We measured venom yield and total protein content, and examined the correlations between venom yield and hatchling size [snout-vent length (SVL) and body mass]. We also analyzed the electrophoretic profiles and enzymatic activities of venoms from hatchlings. Lyophilized venom mass was not correlated with SVL, nor with body mass. Liquid venom mass and total protein content were not correlated with body mass, but were positively correlated with SVL. Venom composition, as shown in SDS-PAGE chromatograms did vary among individuals but there were biochemical differences in activity which had to be due to subtle venom composition differences between the sexes. Female hatchlings showed higher esterolytic and fibrinogenolytic activities but lower proteolytic, collagenolytic, phosphomonoesterase and fibrinolytic activities than male hatchlings. We did not find sexual differences in 5' nucleotidase, phospholipase A(2) and hyaluronidase activities, and l-amino acid oxidase activities in either female or male hatchlings. Within-clutch variation in venoms from D. acutus hatchlings should be attributed to the individual-based differences in presence or absence, and the relative amount of the protein components, and might have a genetic basis.

To solve the puzzle about the right size of the explant of wild medicinal plant Lycoris aurea for tissue culture.Three-size explants: 9.0 x 8.0 mm, 6.0 x 5.0 mm, 3.0 x 2.0 mm of endothecium bulb-scale joined by a strip of stem plate and middle-layer bulb-scale joined by a strip of stem plate were cultured on two kinds of the medium: MS +9 mg/L BA +5 mg/ L NAA +0.7% agar +3% cane sugar and MS +5 mg/L BA +9 mg/L NAA +0.7% agar +3% cane sugar, and the culture effects of the three-size explants for Lycoris aurea were studied.The results showed that the explant size on 6.0 x 5.0 mm of the endothecium bulb-scale cultured on the medium: MS +9 mg/L BA +5 mg/L NAA +0.7% agar +3% cane sugar had the advantage of forming adventitious buds and roots, and inhibiting brown samples, and to the middle-layer bulb-scale explant of the same size cultured on the same medium was next. Correlation analysis showed that the culture effect of the three-size explants on one kind of medium was significantly correlated with that of theirs on another kind of medium, which further proved that the result of Duncans multiple range test, i.e. if the effect of an explant size on one kind of medium were better, its effect on another kind of medium would also be better. Both Duncan's multiple range test and correlation analysis indicated that the effect of the size on 6.0 x 5.0 mm explant of the double endothecium bulb-scale joined by a strip of stem plate was better than those of the other sizes on the experimental explants, and to that of 6.0 x 5.0 mm size of the double middle-layer bulb-scale joined by a strip of stem plate was next.

We kept 48 gravid short-tailed pit vipers (Gloydius brevicaudus) under four laboratory thermal conditions during gestation and collected 10 females from the field soon before they gave birth to test whether Shine's (1995) maternal manipulation hypothesis applies to temperate reptiles. Females thermoregulated more precisely but did not shift their selected body temperatures during pregnancy, with females at high body temperatures giving birth early in the breeding season. The lowest (22 degrees C) and highest (32 degrees C) temperature treatments Increased maternal mortality and resulted in production of offspring with smaller body dimensions. More deformed offspring were produced at 32 degrees C, and more poorly performing offspring were produced at 22 degrees C. In the field, air temperatures lower than 22 degrees C and higher than 32 degrees C accounted for about 9% and 33% of total temperature readings, respectively. However, offspring produced by field-caught females did not differ from those produced by laboratory-kept females with body temperatures optimal for embryonic development in nearly all traits examined. This suggests that in nature, gravid females avoid exposure of their embryos to temperature extremes through thermoregulation. Our study validates the key prediction of the maternal manipulation hypothesis that maternal thermoregulation should enhance fitness-related offspring traits, and demonstrates that viviparity evolves in temperate reptiles because internal development shields offspring from temperature extremes.

Most studies on egg incubation in reptiles have relied on constant temperature incubation in the laboratory rather than on simulations of thermal regimes in natural nests. The thermal effects on embryos in constant-temperature studies often do not realistically reflect what occurs in nature. Recent studies have increasingly recognized the importance of simulating natural nest temperatures rather than applying constant-temperature regimes. We incubated Bungarus multicintus eggs under three constant and one fluctuating-temperature regimes to evaluate the effects of constant versus fluctuating incubation temperatures on hatching success and hatchling phenotypes. Hatching success did not differ among the four treatments, and incubation temperature did not affect the sexual phenotype of hatchlings. Incubation length decreased as incubation temperature increased, but eggs incubated at fluctuating temperatures did not differ from eggs incubated at constant temperatures with approximately the same mean in incubation length. Of the hatchling phenotypes examined, residual yolk, fat bodies and locomotor performance were more likely affected by incubation temperature. The maximal locomotor speed was fastest in the fluctuating-temperature and 30 degrees C treatments and slowest in the 24 degrees C treatment, with the 27 degrees C treatment in between. The maximal locomotor length was longest in the fluctuating-temperature treatment and shortest in the 24 degrees C and 27 degrees C treatments, with the 30 degrees C treatment in between. Our results show that fluctuating incubation temperatures do not influence hatching success and hatchling size and morphology any differently than constant temperatures with approximately the same mean, but have a positive effect on locomotor performance of hatchlings.