Post-autotomy claw regrowth and functional recovery in the snapping shrimp Alpheus angulosus

The ability to regenerate lost tissues, organs or whole body parts is widespread across animal taxa; in some animals, regeneration includes transforming a remaining structure to replace the one that was lost. The transformation of one limb into another involves considerable plasticity in morphology, physiology and behavior, and snapping shrimp offer excellent opportunities for studying this process. We examined the changes required for the transformation of the small pincer to a mature snapping claw in Alpheus angulosus. First molt claws differ from mature claws in overall shape as well as in morphology related to snapping function; nonetheless, shrimp with first molt claws do produce snaps. While most shape variables of second molt claws do not differ significantly from mature claws, the plunger (structure required for snap production) does not reach mature size until the third molt for females, or later for males. Thus, the pincer claw can be transformed into a functional snapping claw in one molt, although both the underlying morphology and superficial shape are not fully regenerated at this stage. The rapid production of a functional snapping claw that we observe in this study suggests that this particular function is of significant importance to snapping shrimp behavior and survival.     

The regenerated tail of juvenile leopard geckos (Gekkota: Eublepharidae: Eublepharis macularius) preferentially stores more fat than the original

The tail of many species of lizard is used as a site of fat storage, and caudal autotomy is a widespread phenomenon among lizards. This means that caudal fat stores are at risk of being lost if the tail is autotomized. For fat-tailed species, such as the leopard gecko, this may be particularly costly. Previous work has shown that tail regeneration in juveniles of this species is rapid and that it receives priority for energy allocation, even when dietary resources are markedly reduced. We found that the regenerated tails of juvenile leopard geckos are more massive than their original counterparts, regardless of dietary intake, and that they exhibit greater amounts of skeleton, inner fat, muscle and subcutaneous fat than original tails (as assessed through cross-sectional area measurements of positionally equivalent stations along the tail). Autotomy and regeneration result in changes in tail shape, mass and the pattern of tissue distribution within the tail. The regenerated tail exhibits enhanced fat storage capacity, even in the face of a diet that results in significant slowing of body growth. Body growth is thus sacrificed at the expense of rapid tail growth. Fat stores laid down rapidly in the regenerating tail may later be used to fuel body growth or reproductive investment. The regenerated tail thus seems to have adaptive roles of its own, and provides a potential vehicle for studying trade-offs that relate to life history strategy.     

The costs of autotomy and regeneration in animals: a review and framework for future research

Many organisms have the ability to shed an appendage (autotomy)to escape a predator or fouled molting event. Despite its immediateadvantage on survivorship, autotomy can have important consequencesfor locomotion, foraging, survivorship, and/or reproduction.Thus, regeneration is a way that animals alleviate some of thecosts associated with losing an appendage. Like autotomy, however,appendage regeneration can have important consequences for avariety of aspects of fitness; in a wide range of amphibians,reptiles, fishes, and arthropods, the allocation of resourcesto regenerate a lost appendage negatively affects somatic orreproductive growth. Previous research into the costs associatedwith regeneration has provided a strong framework to explorehow trade-offs associated with regeneration may have influencedits evolution. However, all research to date describing thecosts and benefits associated with autotomy and regenerationhave compared individuals autotomizing and regenerating an appendagewith individuals that have never lost an appendage. I suggestthat for studies of the evolutionary significance of regeneration,an alternative comparison is between individuals experiencingautotomy without regeneration and individuals experiencing autotomywith regeneration. Future work in this direction promises newinsights into the evolution of regenerative tendencies, as wellas how regeneration may be influencing animal form and function.     

Leave it all behind: a taxonomic perspective of autotomy in invertebrates

Autotomy is defined herein as the shedding of a body part, where (1) the loss of the body part is defensive (autotomy helps prevent the whole animal from being compromised and is in response to external stimuli); (2) shearing occurs by an intrinsic mechanism along a breakage plane (there has been selection for certain body parts to be pulled off easily); and (3) the loss is controlled - the animal moves away from the trapped limb, the loss is under some form of central control (neural or hormonal), or the body part is detached quickly. Autotomy (under this defensive definition) has evolved independently for a diverse array of body parts in many taxa; we have summarised available information for over 200 invertebrate species. The advantages of autotomy include escape from entrapment, an effective form of attack, expulsion of an infected body part or in limiting wounding. We discuss how the incidence of autotomy may therefore be correlated with various traits such as limb function, sex differences, other defence mechanisms, habitat disturbance, and sociality. There are also costs associated with autotomy. Short-term costs include loss of a specialised appendage or organ, reduced speed and stability, or even death. Long-term costs include compromised foraging and feeding (often leading to reduced growth), altered anti-predator, competitive or reproductive behaviour, and even defective development. Regenerating lost appendages may also incur significant costs for the individual. We examine the costs and benefits of autotomy, and discuss the evolutionary selective pressures that contribute to the prevalence and effectiveness of autotomy in invertebrates.     

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.     

Organ repair and regeneration: An overview

A number of organs have the intrinsic ability to regenerate, a distinctive feature that varies among organisms. Organ regeneration is a process not fully yet understood. However, when its underlying mechanisms are unraveled, it holds tremendous therapeutic potential for humans. In this review, we chose to summarize the repair and regenerative potential of the following organs and organ systems: thymus, adrenal gland, thyroid gland, intestine, lungs, heart, liver, blood vessels, germ cells, nervous system, eye tissues, hair cells, kidney and bladder, skin, hair follicles, pancreas, bone, and cartilage. For each organ, a review of the following is presented: (a) factors, pathways, and cells that are involved in the organ's intrinsic regenerative ability, (b) contribution of exogenous cells – such as progenitor cells, embryonic stem cells, induced pluripotent stem cells, and bone marrow‐, adipose‐ and umbilical cord blood‐derived stem cells – in repairing and regenerating organs in the absence of an innate intrinsic regenerative capability, (c) and the progress made in engineering bio‐artificial scaffolds, tissues, and organs. Organ regeneration is a promising therapy that can alleviate humans from diseases that have not been yet cured. It is also superior to already existing treatments that utilize exogenous sources to substitute for the organ's lost structure and/or function(s). (Part C) 96:1–29, 2012. © 2012 Wiley Periodicals, Inc.     

When one tail isn't enough: abnormal caudal regeneration in lepidosaurs and its potential ecological impacts

Abnormal caudal regeneration, the production of additional tails through regeneration events, occurs in lepidosaurs as a result of incomplete autotomy or sufficient caudal wound. Despite being widely known to occur, documented events generally are limited to opportunistic single observations – hindering the understanding of the ecological importance of caudal regeneration. Here we compiled and reviewed a robust global database of both peer‐reviewed and non‐peer reviewed records of abnormal regeneration events in lepidosaurs published over the last 400 years. Using this database, we qualitatively and quantitatively assessed the occurrence and characteristics of abnormal tail regeneration among individuals, among species, and among populations. We identified 425 observations from 366 records pertaining to 175 species of lepidosaurs across 22 families from 63 different countries. At an individual level, regenerations ranged from bifurcations to hexafurcations; from normal regeneration from the original tail to multiple regenerations arising from a single point; and from growth from the distal third to the proximal third of the tail. Species showing abnormal regenerations included those with intra‐vertebral, inter‐vertebral or no autotomy planes, indicating that abnormal regenerations evidently occur across lepidosaurs regardless of whether the species demonstrates caudal autotomy or not. Within populations, abnormal regenerations were estimated at a mean ± SD of 2.75 ± 3.41% (range 0.1–16.7%). There is a significant lack of experimental studies to understand the potential ecological impacts of regeneration on the fitness and life history of individuals and populations. We hypothesised that abnormal regeneration may affect lepidosaurs via influencing kinematics of locomotion, restrictions in escape mechanisms, anti‐predation tactics, and intra‐ and inter‐specific signalling. Behaviourally testing these hypotheses would be an important future research direction.     

Heterochely and handedness in the shore crab Carcinus maenas (L.) (Crustacea: Brachyura)

A large sample ofadult male Carcinus maenas was 79% right-handed and 21% left-handed. A separate sample of 207 intact adult males was divided into left-handed and right-handed crabs and four measurements were taken from all major and minor chelae. Correlation and regression analyses against carapace width on log-transformed data showed that major chelae of right-handed crabs grow proportionately higher with increasing size and the ideal mechanical advantage increases; concurrently, the fingers of the minor chelae grow proportionately longer. The data for left-handed crabs showed greater variability, especially for minor chelae, providing evidence for the concept that left-handedness arises by reversal of handedness following loss of the major chela from the right-hand side. Records of handedness in large samples of non-ocypodid heterochelous brachyuran crabs show a preponderance of right-handedness.     

Molecular methods for diagnosis of Entamoeba histolytica in a clinical setting: an overview

The range of clinical outcomes following Entamoeba histolytica infection is likely to be influenced by the different strains of the parasite already existing in our population. There is a need for developing faster, reliable and reproducible methods for identifying the different strains of E. histolytica. This would have a major impact on the subsequent course of treatment given to patients. In the post-genomic era, different loci of the Entamoeba genome have been targeted for developing suitable probes and genetic markers. This review highlights the development made in this direction and the possibility of using these methods for routine testing of this parasite in clinical samples.     

Chikungunya: an overview

Chikungunya (CHIK), a mosquito borne debilitating disease, is caused by CHIK virus, an alphavirus belonging to the family Togaviridae. The sudden onset of very high fever along with rash, and severe arthralgia especially in the small joints of hands and toes are the characteristics of the disease. It was first reported from Tanzania in 1952–53 and spread subsequently to sub-Saharan Africa, South East Asia and Pacific causing large epidemics. The virus exists in three genotypes, the Asian, West African and East Central South African that are responsible for outbreaks in the respective areas. The first outbreak in Asia was in Bangkok in 1958 followed by other Asian countries. India experienced massive outbreaks of CHIK in the 1960s and early 70s mainly in cities. After a gap of 32 years an explosive outbreak of CHIK devastated the country affecting more than 1.4 million people in 13 states. The epidemic also witnessed many unusual clinico-pathological complications including CHIK associated deaths and mother to child transmission. High morbidity with severe arthralgia persisted for several months made the people mentally and physically weak. This review describes CHIK in general and highlights the various clinico-pathological aspects observed during the recent outbreak.     

Tubular hand bone growth during the latter half of the prenatal period: an allometric analysis

The growth of the 19 tubular hand bones from fetal months 5 to 9 was studied by the allometric method. The hand bones were carefully dissected under a low power stereoscopic microscope. The length and breadth of all bones was found to be monophasic in relation to crown-rump length. In general, maximum bone and ossified shaft lengths in the same row group demonstrate similar allometric coefficients. The specific growth rate of ossified shaft length for all fetal hand bones is greater than the growth rate of maximum length. The highest allometric coefficients for both maximum length and ossified shaft length were obtained from the middle phalanges. The shape of the metacarpals and distal phalanges becomes thinner, while the other bones become thicker or maintain their length-breadth ratio. The relative growth pattern of the first proximal phalanx differed from the middle phalangeal group of the other digits. This suggests that current nomenclatures for the three bones of the pollex is appropriate.     

Genetic ecotoxicology: an overview

The techniques currently available for detecting genotoxin exposure are briefly described and evaluated with regard to the goals of genetic ecotoxicology. The occurrence and significance of genotoxin-induced neoplasia in marine organisms is described. Although there are numerous examples of hotspots where tumour incidences in fish and shellfish have been correlated with raised concentrations of anthropogenic chemicals, causal mechanisms are seldom established. Insufficient information is available to gauge the seriousness of genotoxicity for marine organisms on regional or global scales. The possibility of using marine organisms as sentinels to provide early warning of potential threats to Man is examined. Recognition of the genotoxic disease syndrome in lower animals highlights the need to explore the relationships between DNA damage (adduct formation, gene mutations, etc.) and its phenotypic consequences. Within a given population, not all individuals are equally susceptible to pollutant toxicity (including genotoxicity). The potential for using similarities in phenotypic traits to recognise subsets of individuals within populations possessing similar genotypes is discussed. Changes in heterozygosity and the evolution of genetically resistant populations following exposure to pollution are evaluated in the context of genetic ecotoxicology. Risk assessment procedures are required which enable genotoxin exposure to be related to specific consequences at the community and ecosystem levels. This necessitates both a sound scientific understanding of the mechanisms involved and the development of pragmatic ecotoxicological tools that can be employed by environmental managers.     

Agave biotechnology: an overview

Agaves are plants of importance both in Mexican culture and economy and in other Latin-American countries. Mexico is reported to be the place of Agave origin, where today, scientists are looking for different industrial applications without compromising its sustainability and preserving the environment. To make it possible, a deep knowledge of all aspects involved in production process, agro-ecological management and plant biochemistry and physiology is required. Agave biotechnology research has been focusing on bio-fuels, beverages, foods, fibers, saponins among others. In this review, we present the advances and challenges of Agave biotechnology.     

Plant reintroduction: an overview

The reintroduction of plants will become an increasingly utilized strategy in plant conservation and protected area management. Reintroduction is the deliberate establishment of individuals of a species into an area and/or habitat where it has become extirpated with the specific aim of establishing a viable self-sustaining population for conservation purposes. Plant reintroduction can involve the establishment of an extirpated species into a relatively intact habitat or it can be part of the restoration of a degraded habitat. This will be performed as species become extinct for a number of reasons, such as collecting, introduced herbivores or pathogens and potentially climate change. Although plant reintroductions have the potential to play an important role in species' conservation the long term viability of many reintroductions has yet to be assessed. For the technique to reach it's full potential it requires greater integration with habitat management, restoration and increased international coordination between both theex situ andin situ agencies. In addition the value of introducing stocks of endangered species lacking viable sites for reintroduction to non native sites is discussed.     

SEMG evaluations: an overview

This article reviews the current techniques of surface electromyography (SEMG) assessment. Discussed are static, dynamic, and combination assessment techniques and the rational for their use.     

Phospholipid scramblases: an overview

Phospholipid scramblases are a group of homologous proteins that are conserved in all eukaryotic organisms. They are believed to be involved in destroying plasma membrane phospholipid asymmetry at critical cellular events like cell activation, injury and apoptosis. However, a detailed mechanism of phospholipid scrambling still awaits a proper understanding. The most studied member of this family, phospholipid scramblase 1 (PLSCR1) (a 37kDa protein), is involved in rapid Ca2+ dependent transbilayer redistribution of plasma membrane phospholipids. Recently the function of PLSCR1 as a phospholipids translocator has been challenged and evidences suggest that PLSCR1 acts as signaling molecule. It has been shown to be involved in protein phosphorylation and as a potential activator of genes in response to interferon and other cytokines. Interferon induced rapid biosynthesis of PLSCR1 targets some of the protein into the nucleus, where it binds to the promoter region of inositol 1,4,5-triphosphate (IP3) receptor type 1 (IP3R1) gene and induces its expression. Palmitoylation of PLSCR1 acts as a switch, controlling its localization either to the PM or inside the nucleus. In the present review, we discuss the current understanding of PLSCR1 in relation to its trafficking, localization and signaling functions.     

Gibberellin conjugates: an overview

This article surveys the currently isolated and identified GA conjugates, their synthesis and evaluates modern methods for analysing GA glucose conjugates. The metabolism of applied GAs in higher plant systems leading, in most cases, to GA conjugates is also considered. The enzymology of the formation and hydrolysis of GA glucose conjugates is discussed in connection with their possible physiological function.Abbreviations API = atmospheric pressure ionization - FAB = fast atom bombardment - GA-GE = gibberellin glucosyl ester - GA-O-G = gibberellin-O-glucoside - GC = gas chromatography - GC-MS = combined gas chromatography-mass spectrometry - HPLC = high performance liquid chromatography - LC-MS = combined high performance liquid chromatography-mass spectrometry - MS = mass spectrometry - NMR = nuclear magnetic resonance - PME = permethyl - SIM = selected ion monitoring - TMS = trimethylsilyl     

Handling-related tail loss in an endangered skink: incidence, correlates and a possible solution

Caudal autotomy (tail loss) during capture and handling is widely reported among several families of lizards. Autotomy causes elevated stress levels in lizards, and imposes a significant fitness cost on autotomized individuals. Despite these detrimental impacts, conservation and ethical issues associated with handling-related tail loss have received little attention. We assessed the incidence and correlates of tail autotomy during capture and handling in an endangered skink, the alpine she-oak skink Cyclodomorphus praealtus . A significant proportion (9.3%) of lizards autotomized their tails during capture and handling. Medium-sized lizards were more likely to lose their tails during handling, and this effect was exacerbated at intermediate body temperatures. Probability of autotomy had a complex relationship with cumulative observer experience, independent of other risk factors. Based on the modelled relationship of autotomy with body temperature, we propose that alpine she-oak skinks be cooled immediately after capture to reduce rates of autotomy during subsequent handling.     

Seed size and seedling emergence: an allometric relationship and some ecological implications

We develop a geometric model predicting that maximum seedling emergence depth should scale as the cube root of seed weight. We tested the prediction by planting seeds from 17 species ranging in weight from 0.1 to 100 mg at a variety of depths in a sand medium. The species were spread across 16 genera and 13 families, all occurring in fire-prone fynbos shrublands of South Africa. Maximum emergence depth was found to scale allometrically with seed weight with an exponent of 0.334, close to the predicted value. We used the allometry to predict recruitment response to experimentally simulated variation in fire intensity. Five species with small (<2 mg) seeds and five with large (>10 mg) seeds were planted at ≤20-mm and 40-mm depths and exposed to low and high heat treatments and a control. The allometric equation predicted that species with large seeds would be able to emerge from a depth of 40 mm but those with small seeds would not. Only 1% of 481 seedlings from small-seeded species emerged from the 40-mm planting compared with 40% of 626 seedlings from the large-seeded group. The simulated fire treatments killed seeds in shallow, but not deeper, soil layers. At simulated high fire intensities, seedling emergence was poor in small-seeded species but good in large-seeded species, with most seedlings emerging from the 40-mm planting depth. Seed size could be a useful general predictor of recruitment success under different fire intensities in this system. We suggest that allometric relationships in plants deserve wider attention as predictive tools. Received: 28 September 1998 / Accepted: 3 March 1999