Hair-trigger autotomy in porcelain crabs is a highly effective escape strategy

The benefits of autotomy, the voluntary shedding of limbs, havebeen adequately demonstrated in vertebrates but are poorlystudied in invertebrates. We provide strong experimental evidencefor an antipredatory benefit to autotomy in two porcelain crabs(Petrolisthes cinctipes and P. manimaculis). Since the outcomeof autotomy depends critically on the species of predator andprey involved, we first surveyed field populations of porcelaincrabs to identify ecologically relevant predators to use insubsequent experiments. We then examined the escape tacticsof the porcelain crabs in response to the four potential predatorswe identified, all larger predatory crabs. Cheliped autotomywas induced by three of the predator species (Cancer antennarius,Hemigrapsus nudus, Pachygrapsus crassipes); the fourth didnot attack porcelain crabs. Autotomy occurred in response to34% of all attacks, and in 67% of attacks in which the preywas held at some point by only the cheliped. Autotomy was ahighly effective escape mechanism against these predators;58 of 59 crabs that autotomized escaped, usually while thepredator stopped pursuit to eat the shed cheliped. Relianceon autotomy as a primary mechanism for escaping predators maybe particularly common in small crabs that cannot adequatelydefend themselves by other means and in suspension-feedingcrabs that do not need their chelipeds for feeding.     

The oxidative costs of reproduction are group-size dependent in a wild cooperative breeder

Life-history theory assumes that reproduction entails a cost, and research on cooperatively breeding societies suggests that the cooperative sharing of workloads can reduce this cost. However, the physiological mechanisms that underpin both the costs of reproduction and the benefits of cooperation remain poorly understood. It has been hypothesized that reproductive costs may arise in part from oxidative stress, as reproductive investment may elevate exposure to reactive oxygen species, compromising survival and future reproduction and accelerating senescence. However, experimental evidence of oxidative costs of reproduction in the wild remains scarce. Here, we use a clutch-removal experiment to investigate the oxidative costs of reproduction in a wild cooperatively breeding bird, the white-browed sparrow weaver, Plocepasser mahali. Our results reveal costs of reproduction that are dependent on group size: relative to individuals in groups whose eggs were experimentally removed, individuals in groups that raised offspring experienced an associated cost (elevated oxidative damage and reduced body mass), but only if they were in small groups containing fewer or no helpers. Furthermore, during nestling provisioning, individuals that provisioned at higher rates showed greater within-individual declines in body mass and antioxidant protection. Our results provide rare experimental evidence that reproduction can negatively impact both oxidative status and body mass in the wild, and suggest that these costs can be mitigated in cooperative societies by the presence of additional helpers. These findings have implications for our understanding of the energetic and oxidative costs of reproduction, and the benefits of cooperation in animal societies.     

Salinity effects on arm regeneration in Luidia clathrata (Echinodermata: Asteroidea)

The effect of salinity (20, 25, and 30?psu) on regeneration of two arms of adult starfish Luidia clathrata (n?=?8 per salinity treatment group collected from Pensacola Bay, Florida, USA 30° 20′ N, 87° 13′ W) was examined in a laboratory experiment (November 2009 to March 2010) to test the hypothesis that L. clathrata is adapted to euryhaline conditions found in bays with regards to arm regeneration. Regenerating arm condition (lengths and weights) relative to treatment was 20-psu treatment?<?25-psu treatment?<?30-psu treatment, and non-regenerating arm condition was 20-psu treatment?<?25-psu treatment?=?30-psu treatment. Luidia clathrata is not adapted to lower salinity conditions found in bays with regard to arm regeneration, despite the common occurrence of the species in bays. Lower salinity in bays should reduce the ability of L. clathrata to recover from damage sustained during, or just prior to, low-salinity periods.     

Trade-offs between reproductive and somatic (storage) investments in animals: a comparative test of the Van Noordwijk and De Jong model

Classical life-history theory predicts ‘trade-offs’ between reproductive and somatic investments. However, empirical studies have shown that intraspecific phenotypic correlations between these two resource investments are often positive or nonsignificant, rather than negative as predicted. The model of Van Noordwijk and De Jong (1986) was proposed to explain these unexpected results. According to their model, positive correlations between reproductive and somatic investments will result if individual variation in resource acquisition exceeds that of resource allocation, whereas negative correlations will result if individual variation in resource allocation exceeds that of resource acquisition. To test this model, I used body storage/condition as an index of somatic investment because it is usually strongly related to level of resource acquisition. I predicted that laboratory studies should more often show negative correlations between reproductive and somatic investments than field studies, because individual variation in resource acquisition is expected to be lower in controlled laboratory environments than in variable natural environments. A literature review revealed that correlations between somatic (storage) investment and reproductive investment (estimated as clutch/litter mass, number of offspring per clutch/litter, or number of clutches/litters) among conspecific breeding female animals are more often positive (15 species) or nonsignificant (17 species) than negative (6 species). Moreover, as expected, five of six negative correlations were observed in laboratory studies, whereas 13 of 15 positive correlations were observed in field studies. It is concluded that future empirical and theoretical work on life histories should consider individual variation in both resource acquisition and allocation and the interaction between the two. This revised version was published online in July 2006 with corrections to the Cover Date.     

Sexual size dimorphism in caecilian amphibians: analysis, review and directions for future research

Sexual dimorphism, widespread in the animal kingdom, describes differences between the sexes in size, shape and many other traits. Sexual size dimorphism (SSD) plays a significant role in understanding life history evolution and mating systems. The snakelike morphology of limbless caecilian amphibians lacking obvious secondary sexual characters (in contrast to frogs and salamanders) impedes accurate intrasexual comparisons. In this study, sexual size dimorphism in the oviparous caecilian Ichthyophis cf. kohtaoensis, a phylogenetically basal caecilian, was analysed. Females were larger in all body and head characters tested. However, when adjusted to body size (total length), females differed only in their cloacal shape. Clutch volume was positively correlated to female body size, thus female fecundity increased with body size supporting the hypothesis of a fecundity-selected SSD in the oviparous Ichthyophis cf. kohtaoensis. A review of the present SSD data for caecilians shows that many species are monomorphic for body size but show dimorphism in head size, while other species demonstrate female-biased SSD. Male-biased SSD has not been reported for caecilians. To understand life history evolution in caecilians, further studies on the reproductive biology of other taxa are urgently needed, in particular for rhinatrematids and uraeotyphlids. New data will allow phylogenetically controlled comparative analyses to fully explore the pattern of SSD among caecilian lineages.     

The effects of tail autotomy on survivorship and body growth of Uta stansburiana under conditions of high mortality

We examined the effects of tail autotomy on survivorship and body growth of both adult and juvenile Uta stansburiana by directly manipulating tail condition. Tail loss decreased neither survivorship nor rate of body growth for individuals in two natural populations. Lack of an influence of tail loss on survivorship in these two populations may be the result of high mortality. Under high mortality any differential effects of tail loss will be lower than in populations facing lower mortality. Growth experiments in the laboratory demonstrated that, under conditions of minimal environmental variation and social interactions, there is no tradeoff between body growth and tail regeneration as has been suggested for other species of lizards. One possible reason for this difference is that U. stansburiana does not use the tail as a storage organ for lipids. The original and regenerated tails are composed mainly of protein. In general, any differential body growth between tailed and tailless individuals may be due to social interactions and not a diversion of limited energy into tail regeneration.     

The reptilian oviduct: a review of structure and function and directions for future research

The reptilian oviduct is a complex organ with a variety of functions (albumen production, eggshell production, placentation, oviposition or parturition, and sperm storage), depending on the parity mode of the species in question. These functions are under complex physiological control, the details of which are far from understood. The aims of this review are to summarise the information available concerning the structure and functions of the reptilian oviduct and to highlight areas in particular need of further research.     

Isoflavonic phytoestrogens--new prebiotics for farm animals: a review on research in China

Isoflavones are recognized to be estrogenic compounds that are often associated with a reduced risk of cancers. The estrogenic activity can be enhanced after metabolization to more active compounds such as genistein and daidzein by gut microorganisms. The direct use of these metabolites has been investigated in laboratory rats and farm animals over the last decade. This paper reviews the research progress on the effect of isoflavonic compounds including metabolites on the physiology, gut microbiology and performance of farm animals in China.     

肝再生增强因子研究进展

肝再生增强因子是新近克隆的蛋白质因子,能特异地刺激肝源细胞的增殖,并对ＣＣl4所引起的急性肝衰竭有效治作用。本文综述了肝再生增强因子的发现、基因克隆及组织分布等。目前已开始了该因子的基因工程产品研制,它有望成为一种治疗肝病的新药。     

Sexual selection in hermit crabs: a review and outlines of future research

The information currently available on sexual selection in hermit crabs is reviewed to identify the role of males and females before, during and after mating. According to this information, possible mechanisms of male–male competition, female choice and/or sexual conflict are suggested. Important male components that may affect mating success include dragging the female shell, rotations of the female's shell and male cheliped palpations, and male size and/or shell characteristics (species and size). Possible female determinants of male mating/fertilization success include size (as an indicator of egg production capacity), signalling of sexual receptivity to males, delay from mate guarding to copulation and mating duration. Avenues for deeper exploration in males include the role of the number and morphometry of male sexual tubes during sperm transfer, and whether ejaculate size and sperm number can be adjusted with variable situations of sperm competition intensity and risk. In females it would be interesting to investigate the chemical and behavioural mechanisms affecting spermatophore breakage for sperm release and the variable duration from sperm transfer to spawning. Given these possibilities, and that sperm is externally deposited on the female's body but inside her shell (except for those species that do not use shells, e.g. Birgus , or species where shells are rather small and do not cover the body totally, e.g. Parapagurus ), we conclude that hermit crabs are unique subjects for separating male and female effects, particularly with respect to the applicability of current ideas in sexual selection such as female choice and sexual conflict. Some practical ideas are provided to disentangle both hypotheses using these animals.     

The marbled crayfish: a new model organism for research on development, epigenetics and evolutionary biology

Model organisms have contributed significantly to the understanding of basic biological phenomena. Suitable animal models are at hand for some research disciplines like genetics, development and cell biology but are still sought after for others like epigenetics. Research of the last years has revealed that the marbled crayfish (Marmorkrebs), which was discovered in the mid-1990s, meets researchers' demands for a vigorous, genetically identical and eurytopic laboratory model very well. Its most prominent advantages are production of high numbers of genetically identical offspring, stepwise alteration of the phenotype by moulting, complex morphology and behaviour and sequential generation of segments and limbs. This paper first reviews the discovery and research history of the marbled crayfish, its biology and culture and its special advantages. It then discusses, based on the published data, its suitability as a laboratory model for various research disciplines. The greatest potential of the marbled crayfish lies in epigenetics and environmental epigenomics and in stem cell research and regeneration. The marbled crayfish also appears to be suitable for the investigation of the role of stochastic developmental variation and epigenetic inheritance in evolution and to contribute to evo-devo and eco-devo. This unique crayfish is even of some value for applied biologists, for example as a toxicological test species.     

Venom induces alarm behaviour in the social wasp Polybioides raphigastra (Hymenoptera: Vespidae): an investigation of alarm behaviour, venom volatiles and sting autotomy

Chemicals from the venom gland elicited alarm behaviour and attack in the Asian polistine wasp Polybioides raphigastra. When presented with crushed venom glands workers of this wasp respond with a mass stinging attack. Gas chromatography–mass spectrometry analyses show that the major volatiles in the venom gland are alkanes, monounsaturated alkenes and 2-alcohols. Several pyrazines, a spiroacetal and aromatics were also identified as trace compounds. The anatomy and morphology of the sting apparatus are reported, and we describe sting autotomy in this wasp. This is the first such report for the Ropalidiinae. The structures responsible for autotomy are likely to be large barbs present on the sting lancets, and a conspicuous tooth present on the medial side of the left lancet. Sting autotomy in P. raphigastra probably plays an important role in the localization of sites of attack by wasps defending the nest.     

Offspring growth, survival and reproductive success in the bank vole: a litter size manipulation experiment

To estimate the optimality of brood size, it is essential to study the effects of brood size manipulation on offspring survival and reproductive success. Moreover, testing the generality of the hypothesis of reproductive costs requires experimental data from a diversity of organisms. Here I present data on the growth, survival and reproductive success of bank vole Clethrionomys glareolus individuals from manipulated litters. Furthermore, the survival of mothers whose litter size was manipulated was studied. At weaning, the mean weight of pups from enlarged litters was lower and from reduced litters higher compared to control litters. After winter, at the start of the breeding season, individuals from enlarged litters, especially males, were still lighter than individuals from the other two treatments. Litter enlargements did not increase the number of reproducing female offspring per mother, nor did the litter sizes of female offspring differ between treatments. There were no differences between treatments in winter survival of offspring after weaning, but among female offspring, weaning weight explained the survival probabilities over winter. A higher weight of females at winter determined the probability of starting to reproduce in spring. The survival of mothers did not seem to be influenced by litter manipulation performed the previous year. According to the results, mothers nursing enlarged or reduced litters do not gain any fitness benefits in terms of number of offspring surviving to breeding. The results are consistent with the majority of experiments conducted in birds, which have found costs of enlarged brood appearing as offspring trade-offs rather than parent trade-offs. Received: 14 December 1997 / Accepted: 1 March 1998     

Clutch size and the costs of incubation in the house wren

Trade-offs in the allocation of finite resources among differentstages of a breeding attempt as well as between different reproductiveevents should shape the evolution of life-history traits. Toinvestigate the effects of incubation effort on within-broodand between-brood trade-offs in house wrens (Troglodytes aedon),we manipulated the clutch size that females incubated. We isolatedeffects of incubation by reversing the manipulation at hatchingto allow all parents to provision their natural brood sizes.Females that incubated enlarged clutches had longer incubationperiods than control females, both early and late in the season,suggesting that the experimental treatment increased incubationeffort. Contrary to predictions, however, increased incubationeffort did not adversely affect the allocation of effort tonestling provisioning. Rather, in the early season, but notin the late season, females that incubated enlarged clutchesappeared to allocate more effort to nestling provisioning, producingheavier and larger fledglings than control females. Althoughfemales with enlarged early-season clutches consequently lostmore mass than control females, this was likely an adaptiveresponse to reduce wing loading in anticipation of high provisioningdemands. There were no treatment-related differences in fledglingmass or size, or in female mass loss, in the late season. Thus,elevated incubation demands negatively affected a fitness-relatedtrait (duration of incubation) that may constrain clutch sizebut not the allocation of resources to subsequent stages ofthe same breeding event or to subsequent breeding events. Wesuggest that environmental conditions may mediate clutch-sizeeffects on trade-offs in allocation of resources between incubationand nestling provisioning.     

Lethal and sublethal costs of autotomy and predator presence in damselfly larvae

We studied the costs of lamellae autotomy with respect to growth and survival of Lestes sponsa damselfly larvae in field experiments. We manipulated predation risk by Aeshna cyanea dragonfly larvae and lamellae status of L. sponsa larvae in field enclosures and compared differences in numbers, size and mass of survivors among treatments. In the absence of a free-ranging A. cyanea larva, about 29% of the L. sponsa larvae died. This was probably due to cannibalism. The presence of a free-ranging A. cyanea reduced larval survival by 68% compared to treatments in which it was absent or not permitted to forage on L. sponsa damselflies. Across all predator treatments, lamellae autotomy reduced survival by about 20%. The mean head width and mass of survivors was lower in the enclosures with a free-ranging A. cyanea compared to the other two predator treatments. This suggested that larvae grew less in the presence of a free-ranging predator, indicating that increased antipredator behaviours were more important in shaping growth responses than reduced population density. Mass, but not head width, of survivors was also reduced after autotomy. The fitness consequences of these effects for the adults may be pronounced. In general, these field data strongly suggest that lamellae autotomy affects population regulation of damselflies. Received: 1 February 1999 / Accepted: 22 March 1999     

Old parasites for a new world: the future of paleoparasitological research. a review

Paleoparasitological research has made important contributions to our understanding of parasite evolution and ecology since the 1960s. Since then, most studies have focused on paleoparasitological evidence from single sites or samples. With the development of high throughput sequencing techniques, new avenues of investigation for paleoparasitological material are opening up. Here, I provide an overview of recent developments and highlight how these results will broaden the scope of the field, placing paleoparasitology at the interface of a wide array of studies, including parasitology, climate change, human evolution, and evolutionary processes.     

Biomarkers in cancer screening,research and detection: present and future: a review

Biomarkers provide a powerful and dynamic approach to understanding the spectrum of malignancies with applications in observational and analytic epidemiology, randomized clinical trials, screening, diagnosis and prognosis. Defined as alterations in the constituents of tissues or body fluids, these markers offer a means for homogeneous classification of a disease and risk factor, and they can extend one's basic information about the underlying pathogenesis of disease. The goals in cancer research include finding biomarkers that can be used for the early detection of cancers, design individual therapies, and to identify underlying processes involved in the disease. Because so many myriad processes are involved in the diseased states, the goal is similar to ‘finding a needle in a haystack’. However, the development of many -omic technologies, such as genomics and proteomics, has allowed us to monitor a large number of key cellular pathways simultaneously. This has enabled the identification of biomarkers and signalling molecules associated with cell growth, cell death and cellular metabolism. These are also facilitating in monitoring the functional disturbance, molecular and cellular damage, and damage response. This brief review describes the development of biomarkers in cancer research and detection with emphasis on different proteomic tools for the identification and discovery of new biomarkers, different clinical assays to detect various biomarkers in different specimens, role of biomarkers in cancer screening and last but not the least, the challenges in this direction of cancer research.