梁子湖浮游甲壳动物的生物多样性

基于2006年8月至2008年3月对梁子湖浮游甲壳动物的采样调查,记录了该湖区浮游甲壳动物22种,隶属9科18属,其中枝角类(Cladocera)16种,桡足类(Copepoda)6种,包括9属新记录.物种多样性季节性动态变化明显:枝角类优势种在春、夏和秋冬季依次为透明溞(Daphnia hyalina,优势度Y = 0.80±0.01),小栉溞(Daphnia cristata,Y = 0.50±0.03)和长额象鼻溞(Bosmina longirostris,Y = 0.58±0.04);而桡足类优势种在夏、秋和冬春季依次为长江新镖水蚤(Neodiaptomus yangtsekiangensis,Y = 0.41±0.01)、近邻剑水蚤(Cyclops vicinus,Y = 0.46)和特异荡镖水蚤(Neutrodiaptomus incongruens,Y = 0.65±0.18).浮游甲壳类个体密度以春季最高((292±85) ind/L),夏、秋、冬季渐低(依次为(169±104)、(140±53)、(120±0) ind/L).物种多样性冬春季较低(物种数S≤12,丰富度指数D = 0.77和0.71,香农-威纳指数H = 1.79和1.45),夏秋季较高(S≥17,D = 0.98和0.88,H = 1.78和1.83).梁子湖浮游甲壳类动物多样性年际差异不显著,表明湖区环境条件较为优越、稳定.     

对虾等甲壳类动物肠道与血淋巴菌群的组成、功能与动态平衡调控

对虾等甲壳类动物体内存在2个菌群:肠道菌群和血淋巴菌群。肠道菌群的种类和数量较多,而血淋巴菌群较少。两种菌群均包含益生菌和致病菌,在宿主体内代谢、营养和免疫反应中发挥重要功能。肠道菌群动态平衡的调控主要通过双氧化酶产生的活性氧来完成;血淋巴菌群通过C-型凝集素调控的抗菌肽表达及酚氧化酶原激活系统来维持其动态平衡。阐明对虾等甲壳类体内菌群的组成、功能和动态平衡调控的机理,可以为对虾等经济甲壳类健康养殖的微生态制剂开发和疾病控制提供指导。     

长江口浮游甲壳动物空间分布特征

2010年研究了长江口南、北支浮游甲壳动物的空间分布特征。共采集到浮游甲壳动物50种,其中桡足类39种,枝角类11种。种类数南支高于北支;平均密度北支高于南支,南、北支分别为1.7 ind./L和61.8 ind./L。基于群落相似性矩阵的CLUSTER聚类和MDS分析显示,在群落相似性为40%时,长江口区域浮游甲壳动物群落可分为北支组、南支组1和南支组2共3组。3组的优势种有差异。浮游甲壳动物的平均密度变化趋势为北支组（61.8±22.11 ind./L）〉南支组1（3.07±2.06 ind./L）〉南支组2（0.72±0.45 ind./L）。盐度、潮汐和径流量是影响长江口南北支浮游甲壳动物种类组成、密度和空间分布差异的重要环境因素。     

All or nothing: Switch to high current reproductive investment under risk of starvation in male kelp crab

One of the key features in reproduction of polygynous species is seminal recovery after mating. However, it is poorly known how environmental factors affect the recuperation period of seminal material. This study aims to test plasticity in recovery of seminal reserves in response to distinct environmental conditions of the kelp crab Taliepus dentatus. Male crabs were maintained after depletion of seminal reserves in one of eight different treatments in a factorial design of temperature (12 and 16°C), food availability (with alimentation and food deprivation), and time period (15 and 30 days), simulating different environmental situations in the laboratory to which the crab might be exposed to along its distribution. Temperature and food availability modulated the seminal recovery period in T. dentatus. Complete replenishment was reached within 30 days in all treatments (i.e., 12 and 16°C each with alimentation and food deprivation), but the highest recovery index was found in crabs without food provision (16°C). In this condition, the recovery index was twice as high compared with males maintained at a similar temperature but with feeding. Prolonged starvation at 16°C may be extremely stressful conditions for male crabs, during which risk to die probably triggered a concentration of the reproductive effort in favor of immediate reproduction. This suggests that plasticity of energy allocation toward reproduction may be expressed during extremely suboptimal conditions, which might be a similar strategy as proposed by the terminal investment hypothesis. The generally relatively fast seminal recovery regardless of the temperature may explain the kelp crab's continuous mating throughout the year.     

Neuropeptides regulating development and reproduction in insects

Abstract.   This review deals with those neuropeptidic hormones that are completely known in their primary structure together with the control processes that are linked directly or indirectly to development and reproduction. Actions are assessed for neuropeptides that regulate ecdysteroid and Juvenile Hormone production; oocyte growth or yolk deposition; and ecdysis and courtship behaviour. The combined data on the primary sequence, gene expression, biosynthesis, release, interaction with the receptor and mode of action provide an accurate account of the current knowledge on how these peptides function.     

Gregarious aggregative behavior in the marine isopod Cirolana harfordi

Gregarious huddling behavior where animals seek the close company of conspecifics is thought to have facilitated the evolutionary transition from sea to land in some species of isopods, the theory being that closely apposed bodies decrease surface area and reduce desiccation. In this study, specimens of the marine isopod Cirolana harfordi were investigated to determine whether they displayed gregarious aggregative behavior. Animals were placed in a 20‐cm‐diameter acrylic cylinder arena that contained two 5‐cm‐diameter circular acrylic shelters that were tinted red (to reduce light transmittance), one at either end of the arena. Specimens of C. harfordi chose one of the two identical shelters at random, and the majority of animals congregated under this winning shelter. When an arena with one shelter tinted red and one clear shelter was used, the majority of animals congregated under the red shelter. These data indicate that the aggregative behavior displayed by this marine isopod species is driven by gregarious, conspecific attraction as well as reactions to environmental heterogeneity and negative phototaxis. Gregarious behavior in this marine isopod may afford the species advantages other than avoiding desiccation.     

Sex and reproductive stage differences in the growth,metabolism, feed,fecal production,excretion and energy budget of the Amazon River prawn (Macrobrachium amazonicum)

The aim of this study was to evaluate differences in various physiological measures (growth, fecal production, feed intake, nitrogenous excretion, oxygen consumption, energy substrate used, and energy budget) among males, ovigerous females and non-ovigerous females of the freshwater prawn Macrobrachium amazonicum. This species exhibits pronounced sexual dimorphism and different male morphotypes and has the potential for use in aquaculture. Males and non-ovigerous females were studied for 30?days. Ovigerous females were studied for 10?days. Prawns were fed commercial prawn food, and all males were of the Translucent Claw (TC) morphotype. The results demonstrate physiological differences both between males and females and between females of different reproductive stages. Males had higher rates of ingestion, growth and oxygen consumption and less fecal loss than females. We postulate that in the absence of other morphotypes, TC males may exhibit increased growth rates. Males and females used protein as an energy substrate. Males channeled approximately 9% of their energy budget into growth, whereas non-ovigerous and ovigerous females channeled only 1.4?±?0.4 and 0.07?±?0.07%, respectively. Whereas males and non-ovigerous females channeled 9.0?±?9.74 and 61.8?±?3.0%, respectively, of the energy ingested into metabolism, ovigerous females channeled 97.7?±?4.7% into metabolism, likely due to the frequent beating of their pleopods, which oxygenates and cleans the eggs. As reported for marine prawns, males and non-ovigerous females of M. amazonicum lost approximately 5% of their ingested energy in exuviae. The physiological differences observed between the sexes and between females of different reproductive stages might reflect corresponding differences in patterns of activity, growth, and reproduction.     

Anostracans and microcrustaceans as potential food sources of waterbirds on sodic pans of the Hungarian plain

Hungarian sodic water bodies have a rich macro- and microcrustacean fauna due to the lack of fish populations. The crustacean population is very abundant, for this reason these wetlands provide good feeding resources for waterbirds. The density of macro- and microcrustacean populations together with feeding waterbirds was investigated in March, April, and May of 2002, on two characteristic sodic pans, “Kelemen-szék” and “Zab-szék”. The following dabbling-filtering waterfowls and pelagic forager wader species were counted: northern pintail (Anas acuta), northern shoveler (Anas clypeata), garganey (Anas querquedula), common teal (Anas crecca), avocet (Recurvirostra avosetta), spotted redshank (Tringa erythropus), greenshank (Tringa nebularia), and marsh sandpiper (Tringa stagnatilis). The dominant macrocrustacean species was the [Anostraca – Branchinectidae] natronophile Branchinecta orientalis, and its density was significantly higher in Zab-szék than in Kelemen-szék. The microcrustacean zooplankton community was also different in the pans, [Cladocera] Daphnia magna density was significantly higher in Kelemen-szék than in Zab-szék, but the density of the [Copepoda] natronophile Arctodiaptomus spinosus, was higher in Zab-szék than in Kelemen-szék. The density of the investigated waterbird species was also significantly higher in Zab-szék than in Kelemen-szék during spring. We can conclude that the macrocrustacean B. orientalis is one of the most important potential food resources for migrating pelagic foraging waders in spring on characteristic Hungarian sodic pans. However, the most abundant available food item for waterbirds are copepod microcrustacean zooplankton, which have a biomass that is larger by approximately one order of magnitude than the macrocrustacean zooplankton biomass. Considering the lack of submerged water vegetation, we suggest that planktonic microcrustaceans are an important food resource for dabbling-filtering ducks because they can utilise the small crustacean biomass more effectively than the less abundant and rapidly moving macrocrustacean B. orientalis.     

Phylogenetic distance of Thelohania butleri Johnston, Vernick, and Sprague, 1978 (Microsporidia; Thelohaniidae), a parasite of the smooth pink shrimp Pandalus jordani, from its congeners suggests need for major revision of the genus Thelohania Henneguy, 1892

Thelohania butleri, a microsporidian that causes mortality and commercial losses in the smooth pink shrimp Pandalus jordani, is of taxonomic interest as a species resembling the poorly studied type species, Thelohania giardi, of the large, polyphyletic genus Thelohania. We examined the ultrastructure of T. butleri to confirm its identity and reconstructed phylogenies using ribosomal DNA to find the relationship of T. butleri with other Thelohania species in crayfish and ants. Light and transmission electron microscopy from specimens collected from the type locality, the Pacific coast of Canada, confirmed the identity and demonstrated a development similar to that of T. giardi, involving a series of binary fissions without formation of a plasmodium. Phylogenetic analyses consistently showed T. butleri to be distantly related to other Thelohania species, and closely related to species from marine decapods within a larger fish-parasitic clade. Together, features such as host group and habitat, developmental morphology, and phylogeny suggest T. butleri may be a closer relative to T. giardi than any other Thelohania species represented by DNA data so far, and thus imply species from crayfish and ants may not belong in this genus. Results also confirm that genus Thelohania and family Thelohanidae are in need of revision.     

Early pattern of calcification in the dorsal carapace of the blue crab, Callinectes sapidus

The pattern of calcium carbonate deposition was observed in the dorsal carapace of premolt (D2-D3) and early postmolt (0-48 h) blue crabs, Callinectes sapidus, using scanning (SEM) and transmission (TEM) electron microscopy. Samples of dorsal carapace for SEM were quick-frozen in liquid nitrogen, subsequently lyophilized, and viewed using secondary and backscattered electrons as well as X-ray maps of calcium. Pieces of lyophilized cuticle were also embedded in epoxy resin and subsequently sectioned and viewed with TEM and SEM. Fresh pieces of dorsal carapace for TEM were also fixed in 2.5% glutaraldehyde in phosphate buffer followed by postfixation in 1% OsO4 in cacodylate buffer. Calcium concentrations were determined using atomic absorption spectrophotometry and quantitative X-ray microanalysis. Calcium accumulation began in the cuticle at 3 h postmolt at the epicuticle/exocuticle boundary and at the distal and proximal margins of the interprismatic septa (IPS). The bidirectional calcification of the IPS continued until the two fronts met at 5-8 h postmolt. The roughly hexagonal walls of the IPS formed a honeycomb-like structure that resulted in a rigid cuticle. The walls of the canal containing sensory neurons also calcified at 3 h, thereby imparting rigidity to the structure and additional strength to the cuticle. Examination of thin sections of lyophilized cuticle and fixed cuticle revealed that the first mineral deposited is more soluble than calcite and is probably amorphous calcium carbonate. The amorphous calcium carbonate is transformed to calcite along a front that follows the original deposition and is probably controlled by a specialized matrix within the IPS. Since amorphous calcium carbonate is isotropic, it would also make the mineral in the exocuticle stronger by an equal distribution of mechanical stress.