Phylogenetic relationships between spiny, slipper and coral lobsters (Crustacea, Decapoda, Achelata)

Molecular data can aid in the resolution of conflicting hypotheses generated through difficulties in the interpretation of morphological data and/or an incomplete fossil record. Moreover, the reconstruction of phylogenetic relationships using molecular data may help to trace back the origin of morphological innovations which had a major impact on the radiation of a taxonomical group. In this work, different nuclear (18S, 28S, and H3) and mitochondrial (16S and COI) gene regions were sequenced in a total of 35 Achelatan species to test conflicting hypotheses of evolutionary relationships within the Achelata infraorder and solve the taxonomic disagreements in the group. The combined molecular dataset strongly supports the hypothesis that Achelata is a monophyletic group composed of two main families: Palinuridae and Scyllaridae. Synaxidae is found to be a polyphyletic group, which should be included within Palinuridae. Consequently, our results indicate that the origin of the stridulating organ occurred only once during Achelata evolution. Finally, the two main clades found within the Scyllaridae are in agreement with previous inferences based on adult morphological data. The dating of divergence of Achelata obtained with a relaxed-clock model is compatible with previous hypotheses of a Triassic origin of the Achelata.     

Differences in life-history and ecological traits between co-occurring Panulirus spiny lobsters (Decapoda,Palinuridae)

Coexistence of closely related species may be promoted by niche differentiation or result from interspecific trade-offs in life history and ecological traits that influence relative fitness differences and contribute to competitive inequalities. Although insufficient to prove coexistence, trait comparisons provide a first step to identify functional differences between co-occurring congeneric species in relation to mechanisms of coexistence. Here, a comparative review on life history and ecological traits is presented for two pairs of co-occurring species of spiny lobsters in the genus Panulirus: Panulirus gracilis and Panulirus inflatus from the Eastern Central Pacific region, and Panulirus argus and Panulirus guttatus from the Caribbean region. Panulirus gracilis and Panulirus inflatus have similar larval, postlarval, and adult sizes and a similar diet, but differ in degree of habitat specialization, fecundity, and growth rate. However, little is known on behavioral traits of these two species that may influence their competitive abilities and susceptibility to predators. The more abundant information on Panulirus argus and Panulirus guttatus shows that these two species differ more broadly in degree of habitat specialization, larval, postlarval and adult sizes, diet, fecundity, growth rate, degree of sociality, defense mechanisms, susceptibility to predators, and chemical ecology, suggesting a greater degree of niche differentiation between Panulirus argus and Panulirus guttatus than between Panulirus gracilis and Panulirus inflatus. Whether the substantial niche differentiation and apparent interspecific trade-offs between Panulirus argus and Panulirus guttatus relative to Panulirus gracilis and Panulirus inflatus reflect an earlier divergence of the former pair of species in the evolution of the genus constitutes an intriguing hypothesis. However, whether or not post-divergence evolution of each species pair occurred in sympatry remains uncertain.     

An electromagnetic tracking system for studying the movements of rock (spiny) lobsters

A simple and inexpensive method for examining the movements of rock (spiny) lobsters is described. Electromagnetic tags emitting a pulsed signal were detected in loop antennae placed on the bottom in a grid pattern within a shallow coastal reef area. Signals were received in a tuned receiver and then interpreted using an oscilloscope. Results showing examples of the nocturnal movements of Panuliruscygnus George the western rock lobster in Western Australia are presented.     

白斑综合症病毒与对虾血淋巴细胞的体外结合实验

通过差速离心和蔗糖密度梯度离心,从感染了白斑综合症病毒(WSSV)的病虾头胸部分离了WSSV,利用地高辛对病毒蛋白进行了标记(DIG-WSSV),以体外培养的对虾血淋巴细胞为吸附基底,观察和分析了病毒与细胞间的结合现象及特性。以NBT/BCIP为酶反应显色底物观察到在细胞周围形成许多暗紫色颗粒,证实病毒与细胞间存在着稳定的结合。以OPD为酶反应显色底物分析了结合反应的特性:当DIG-WSSV维持恒定值时,随着血淋巴细胞数量的增加结合显色增强,细胞数量达到1.2104cells/孔,492nm处的吸光值达到饱和;当血淋巴细胞数量维持恒定值时,随着DIG-WSSV蛋白含量的增加显色增强,且在DIG-WSSV的蛋白浓度达到4g/孔时,492nm处的吸光值达到饱和;未标记WSSV可竞争抑制血淋巴细胞与DIG-WSSV间的结合作用。进一步的研究得出:4℃下,随着结合时间的延长显色增强,但继续延长结合时间显色反而减弱;缓冲液的渗透压对结合结果影响甚微,而酸性条件利于病毒与细胞间的结合。37℃孵育对病毒结合活性影响不大,55℃和70℃孵育可显著影响病毒的结合活性;短时间超声波处理病毒可增加病毒结合能力,长时间超声波处理可破坏病毒结合能力;有机溶剂处理同样可破坏病毒结合能力,其中尤以氯仿/甲醇的处理更为激烈;不同的去垢剂对病毒结合活性的影响结果不同:SDS和脱氧胆酸钠可以降低病毒的结合活性,而Triton X-100和NP-40可以提高病毒的结合活性。       

Detection of Taura syndrome virus (TSV) strain differences using selected diagnostic methods: diagnostic implications in penaeid shrimp

Positive results were obtained with nested white spot syndrome virus (WSSV) diagnostic PCR performed on 5 commercial brands of dry-packed Artemia cysts using several WSSV genomic sequence-specific primers. In 2 brands, PCR and nucleotide sequence analysis found C-->T and C-->G point mutations in the pms 146 WSSV amplicon, but in all 5 brands, the nucleotide sequences that were successfully amplified by the rrl, rr2 and tk-tmk gene-specific primer sets were identical to those of Penaeus monodon WSSV. However, despite the inarguable presence of WSSV or WSSV-like template DNA, we were unable to detect WSSV by PCR in hatched nauplii derived from PCR-positive cysts or in P. monodon postlarvae fed Artemia nauplii hatched from such cysts. Most simply, these results suggested that the cysts were externally contaminated with WSSV or WSSV-like template material that was removed during hatching and washing of the nauplii. Given the small sequence variations found, it may also have been a variety of WSSV non-infectious for P. monodon or Artemia and derived from other crustaceans or arthropods in the Artemia environment. However, we could not establish this conclusively and a small possibility remained that the PCR template in these tests was derived from WSSV template present internally in the cysts and derived from infected Artemia adults. However small, this possibility must be vigorously tested, given the impact that a positive outcome could have on the shrimp industry.     

Preliminary experiments on the cryopreservation of penaeid shrimp (Penaeus japonicus) embryos, nauplii and zoea

To improve availability of penaeid seedstock during periods of high demand, experiments were conducted to determine the feasibility of stockpiling embryos by freezing them. Embryos were screened for developmental stage; cryoprotectants, chilling effects, and freezing regimens were likewise evaluated. Juvenile forms (embryos, nauplii and zoea) of Penaeus japonicus were exposed to various cryoprotectants, including dimethyl sulfoxide, glycerol, methanol, ethylene glycerol and polyethylene glycol 300 under ambient temperature (25 degrees C). Following this bioassay, maximum safe concentrations of each cryoprotectant were tested on the juveniles under chilling to 0 degree C and with 42 freezing regimens. Methanol was found to be relatively nontoxic. Early developmental stages were the most sensitive to chilling. Initial attempts to freeze P. japonicus juveniles were reported. The survival rate of nauplii and zoea treated with 10% methanol in natural sea water (35 ppt salinity) and frozen to -15 degrees C was 85%, and some nauplii and zoea survived freezing to -25 and -196 degrees C. However, no treatment yielded normal nauplii or zoea after freezing.     

Source and specificity of chemical cues mediating shelter preference of Caribbean spiny lobsters (Panulirus argus)

Caribbean spiny lobsters display a diversity of social behaviors, one of the most prevalent of which is gregarious diurnal sheltering. Previous research has demonstrated that shelter selection is chemically mediated, but the source of release and the identity of the aggregation signal are unknown. In this study, we investigated the source and specificity of the aggregation signal in Caribbean spiny lobsters, Panulirus argus. We developed a relatively rapid test of shelter choice in a 5000-l laboratory flume that simulated flow conditions in the spiny lobster's natural environment, and used it to examine the shelter preference of the animals in response to a variety of odorants. We found that both males and females associated preferentially with shelters emanating conspecific urine of either sex, but not with shelters emanating seawater, food odors, or the scent of a predatory octopus. These results demonstrate specificity in the cues mediating sheltering behavior and show that urine is at least one source of the aggregation signal.     

Sampling and evaluation of white spot syndrome virus in commercially important Atlantic penaeid shrimp stocks

In 1997, white spot syndrome virus (WSSV) was discovered in shrimp culture facilities in South Carolina, USA. This disease was known to cause devastating mortalities in cultured populations in Southeast Asia and prompted concern for the health of wild populations in the USA. Our study surveyed wild shrimp populations for the presence of WSSV by utilizing molecular diagnostics and bioassay techniques. A total of 1150 individuals (586 Litopenaeus setiferus, 477 Farfantepenaeus aztecus and 87 F. dourarum) were examined for the presence of WSSV DNA by PCR. A total of 32 individuals tested positive and were used in a bioassay to examine the transmission of disease to healthy individuals of the culture species L. vannamei. DNA sequencing of PCR products from a positive individual confirmed that the positive individuals carried WSSV DNA. Significant mortalities were seen in test shrimp injected with tissue extracts from heavily infected wild shrimp. These data confirm the existence of WSSV in wild shrimp stocks along the Atlantic Coast and that the virus can cause mortalities in cultured stocks.     

Molecular epidemiology of Vibrio nigripulchritudo, a pathogen of cultured penaeid shrimp (Litopenaeus stylirostris) in New Caledonia

A collection of 57 isolates of Vibrio nigripulchritudo from either diseased or healthy shrimp and from shrimp farms environment was studied in order to gain a better understanding of the epidemiology of this pathogen, notably isolated from two distinct shrimp disease complexes. Molecular typing using two different techniques, arbitrarily primed PCR (AP-PCR) and multi-locus sequence typing (MLST), studied together with experimental pathology data allowed a relevant epidemiological insight into this possibly emerging pathogen. Additionally, results obtained with the two molecular typing techniques were congruent and allowed discriminating the strains associated with the "Summer Syndrome" from strains isolated from other contexts, especially the other shrimp vibriosis "Syndrome 93". These results highlight that the "Summer Syndrome" is most probably caused by an emergent clonal pathogen that therefore deserves surveillance and that AP-PCR can satisfactorily be used for that purpose.     

An anticoagulant solution for haemolymph collection and prophenoloxidase studies of penaeid shrimp (Penaeus californiensis)

• 1.1. An anticoagulant solution was designed from data on osmolality, ionic concentration and pH to resemble shrimp haemolymph.
• 2.2. This Shrimp Salt Solution (SSS) prevents coagulation and prophenoloxidase system activation during the extraction of shrimp haemolymph.
• 3.3. The location of the the proPO system in the brown shrimp (Penaeus californiensis) was determined using this anticoagulant solution.

     

Effects of mannan oligosaccharide dietary supplementation on performances of the tropical spiny lobsters juvenile (Panulirus ornatus,Fabricius 1798)

The effects of dietary mannan oligosaccharide (MOS) (Bio-Mos^®, Alltech, USA) on the growth, survival, physiology, bacteria and morphology of the gut and immune response to bacterial infection of tropical rock lobsters (Panulirus ornatus) juvenile were investigated. Dietary inclusion level of MOS at 0.4% was tested against the control diet (trash fish) without MOS inclusion. At the end of 56 days of rearing period, a challenged test was also conducted to evaluate the bacterial infection resistant ability of the lobsters fed the two diets. Lobster juvenile fed MOS diet attained 2.86 ± 0.07 g of total weigh and 66.67 ± 4.76% survival rate which were higher (P < 0.05) than the lobsters fed control diet (2.35 ± 0.14 g total weight and 54.76 ± 2.38% survival rate, respectively) thus providing the higher (P < 0.05) specific growth rate (SGR) and average weekly gain (AWG) of lobsters fed MOS diet. Physiological condition indicators such as wet tail muscle index (Tw/B), wet hepatosomatic index (Hiw) and dry tail muscle index (Td/B) of the lobsters fed MOS supplemented diet were higher (P < 0.05) than that of the lobsters fed the control diet. Bacteria in the gut (both total aerobic and Vibrio spp.) and gut's absorption surface indicated by the internal perimeter/external perimeter ratio were also higher (P < 0.05) when the lobsters were fed MOS diet. Lobsters fed MOS diet were in better immune condition showed by higher THC and GC, and lower bacteraemia. Survival, THC, GC were not different among the lobsters fed either MOS or control diet after 3 days of bacterial infection while bacteraemia was lower in the lobsters fed MOS diet. After 7 days of bacterial infection the lobsters fed MOS diet showed higher survival, THC, GC and lower bacteraemia than the lobsters fed the control diet. The experimental trial demonstrated the ability of MOS to improve the growth performance, survival, physiological condition, gut health and immune responses of tropical spiny lobsters juveniles.     

Development of a real-time PCR assay for detection of monodon baculovirus (MBV) in penaeid shrimp

A real-time PCR method was developed to detect monodon baculovirus (MBV) in penaeid shrimp. A pair of MBV primers to amplify a 135 bp DNA fragment and a TaqMan probe were developed. The primers and TaqMan probe were specific for MBV and did not cross react with Hepatopancreatic parvovirus (HPV), White spot syndrome virus (WSSV), Infectious hypodermal and haematopoietic virus (IHHNV) and specific pathogen free (SPF) shrimp DNA. A plasmid (pMBV) containing the target MBV sequence was constructed and used for determination of the sensitivity of the real-time PCR. This real-time PCR assay had a detection limit of one plasmid MBV DNA copy. Most significantly, this real-time PCR method can detect MBV positive samples from different geographic locations in the University of Arizona collection, including Thailand and Indonesia collected over a 13-year period.     

Evolutionary morphology of the hemolymph vascular system in hermit and king crabs (Crustacea: Decapoda: Anomala)

The morphological transformation of hermit crabs into crab‐like king crabs in the evolution of decapod crustaceans represents a remarkable case of carcinization or evolutionary shaping into a crab‐like form. In this study, we focus on internal organs such as the hemolymph vascular system and adjacent anatomical structures of several Recent hermit crab (Paguridae) and king crab (Lithodidae) species. There are various correspondences in the morphology of the arterial systems in the dorsal cephalothorax of the two taxa, especially with regard to the anterior aorta, anterior lateral arteries, and hepatic arteries. In the pleon, the posterior aorta in both taxa displays a proximal bifurcation and follows an asymmetrical course. The ventral vessel system, on the other hand, which mainly supplies the limbs, differs significantly between the taxa, with pagurids displaying the plesiomorphic condition. The pattern of the ventral vessel system in Lithodidae is influenced by morphological transformations of integumental structures during carcinization. One of these transformations was the broadening of the sternites, which resulted in a widening of the space between the endosternites. In addition, changes in the morphology of the endophragmal skeleton in Lithodidae led to an increase in the potential for intraspecific variability and interspecific variation in the arterial branching pattern. J. Morphol., 2013. © 2013 Wiley Periodicals, Inc.     

How lobsters,crayfishes, and crabs locate sources of odor: current perspectives and future directions

Olfactory orientation poses many challenges for crustaceans in marine environments. Recent behavioral experiments lead to a new understanding of the role of multiple sensory appendages, whereas application of non-invasive chemical visualization techniques and biomimetic robotics have allowed researchers to correlate the stimulus environment with behavior and to directly test proposed orientation mechanisms in decapod crustaceans.     

Abundance and seasonal migrations of the penaeid shrimp Metapenaeus affinis (H. Milne-Edwards) within Iraqi waters

Migration of Metapenaeus affinis (H. Milne-Edwards) from the Arabian Gulf to nursery grounds in the inland waters of Iraq extends from May/June to January/February. Shrimp ranging in size from 3–125 mm total length were found in inland waters. In the shallow waters of the Al-Assaflya small-sized shrimp only were caught, while in the Marshes large-sized shrimp were abundant. Maximum numbers of recruits were recorded when temperatures reached 23–25 °C. However, the discharge of the Shatt Al-Arab may also be an important factor regulating recruitment.The growth rates of small shrimp were higher than those of large ones. There mostly was, a preponderance of females over males. Spawning at sea appears to occur immediately after emigration. Gonad development was not observed. Commercial landings, at the two main fish markets at Basrah, during September–November 1985 averaged 1000 kg day^–1.     

Agonistic interactions between invasive green crabs, Carcinus maenas (Linnaeus), and sub-adult American lobsters, Homarus americanus (Milne Edwards)

The invasive green crab, Carcinus maenas, has recently expanded its range into the Southern Gulf of St. Lawrence, where there is potential for substantial niche overlap with juvenile American lobsters, Homarus americanus. We used two experiments to elicit, record and analyze the agonistic interactions of adult green crabs (carapace width of 63-75 mm) and sub-adult (carapace length of 55-70 mm) lobsters. The first experiment gave each animal equal access to a limited food resource. The green crabs were first to the food in significantly more trials, spent a significantly greater proportion of time with the food, and were able to successfully defend the food from attacks by the heavier lobsters. In the second experiment, we allowed the lobsters to gain possession and initiate feeding on the food before releasing the green crabs. In these trials, the lobsters spent significantly more time with the food, and were able to defend the food from the green crabs. The results of both experiments are discussed in the context of game theory. The different behaviour of the crustaceans in the two experiments is consistent with the “bourgeois” strategy in a hawk and dove game simulation. With this strategy, an animal acts like a hawk if in possession of a resource, but acts like a dove if the other animal is in possession of the resource. The fact that the green crabs were able to physically compete with, and in many cases dominate the larger, heavier lobsters supports the potential for competitive impacts of green crabs on sub-adult lobsters.     

Peritrophic membrane of the penaeid shrimp Sicyonia ingentis: structure, formation, and permeability

Peritrophic membranes (PTMs) are secreted acellular layers that separate ingested materials from the gut epithelium in a variety of invertebrates. In insects and crustaceans, PTMs are produced in the midgut trunk (MGT, or intestine), but the MGT in decapod crustaceans, unlike that of insects, is not involved with digestion or absorption of food. We demonstrate that the PTM in the penaeid shrimp Sicyonia ingentis is similar to that in other crustaceans that have been studied and is primarily composed of chitin. The lectin WGA binds only to the PTM and glycocalyx along the microvilli of the midgut cells, which is consistent with the suggestion that the chitin is synthesized along the microvilli. The PTM is only permeable to inert particles smaller than 20 nm. We also describe the secretion of granules, which fill the apices of the epithelial cells, into the ectoperitrophic space. Although their function is not clear, they do not contribute to the PTM.