Catch, survey and life-history data for shrimp (Pandalus borealis) off Jan Mayen

The Jan Mayen area has an extreme environment with low temperatures and infrequent, but abrupt temperature changes. The shrimp population here is considered to be on its edge of distribution. The life-history parameters are in the same range as in other high-latitude shrimp populations and are characterized by slow growth, large size at maturation and extended longevity. Irregular and sporadic commercial exploitation limit fishing mortality and give the population life-history parameters not previously seen in other areas. The Jan Mayen shrimp are large compared to, e.g., the Barents Sea shrimp and can reach a maximum carapace length (L_max) of 37 mm and an age of 10–11 years. The large size at sex transformation (L₅₀, >24 mm) and analyses of length–frequency distributions indicate that the shrimp may be 6–7 years of age before changing sex. The change in L_max and L₅₀ observed during the study period is probably caused by increased natural mortality due to sudden temperature changes or due to increased predation, rather than increased growth rates. The life-history strategy of shrimp in the Jan Mayen area can be explained by factors such as depth, temperature and population density variations caused by fluctuation in recruitment and mortality.The shrimp fisheries in the Jan Mayen area began in the late 1970s and reached an annual landing of 2000 tonnes in 1985, and since then landings have oscillated around 500 tonnes depending on a combination of factors. The survey indices of stock biomass varied between 3000 and 6600 tonnes. For most years, the highest shrimp densities are at a depth of 200–299 m, while large shrimp (and therefore also female shrimp) are dominant at depths greater than 300 m.Fish community data were studied as the composition of the demersal fish community is an integrated response to environmental conditions and as predation affects the shrimp stock. Polar cod and capelin are the most abundant fish species in the study area. A high number of blue whiting was registered in 1979, but the number declined in 1980 and 1981 as temperature decreased. During the surveys in 1994 and 1995, no blue whiting was registered. A few individuals were found again in the 1999 samples. The number of Greenland halibut has declined from the beginning of the 1980s to the 1990s.     

Spatial and diurnal distribution of invertebrate and fish fauna of a Zostera marina bed and nearby unvegetated sediments in Damariscotta River, Maine (USA)

Fish, epibenthos and macroinfauna were collected in a Zostera marina bed and nearby unvegetated sediments in the estuary of the Damariscotta River, on the mid-coast of Maine. Samples of epibenthic fauna and fish were collected at low tides both during day and night, and samples of infauna at low tides during the day. The mean density of Zostera shoots in the study area was 335 m⁻². Abundance and species number of fish were greater at night than during the day and greater in eelgrass beds (Z. marina) than in unvegetated habitats. Daytime fish collections were dominated by Atlantic silversides (Medinia medinia), while juvenile winter flounder (Pseudopleuronectes americanus) dominated night collections. Also Zostera-associated epifaunal abundances and number of species were significantly higher at night than during the day. Mysis stenolepis, Idotea balthica and Littorina obtusata were dominant species in the epifauna samples. Of the total of 37 invertebrate species encountered, only five occurred both in the infaunal and epifaunal samples. Nineteen different taxa were collected from the benthic core samples. The most abundant invertebrate infaunal taxa were sipunculids, the polychaete Nereis virens, and oligochaetes. Infaunal invertebrate abundances and species diversity were significantly higher in eelgrass beds than in unvegetated sediments. The abundance and number of species of benthic invertebrates were also positively correlated to seagrass biomass. Community diversity values (H′) were relatively low but fit well in the general pattern of decreasing diversity towards northern latitudes.     

Comparing quality of estuarine and nearshore intertidal habitats for Carcinus maenas

Estuarine and nearshore marine areas are vital habitats for several fish and benthic invertebrates. The shore crab Carcinus maenas (Crustacea: Brachyura: Portunidae) inhabits a variety of coastal, estuarine and lagoon habitats. At low tide, habitat structural complexity may be most important for crabs in the intertidal, providing refuge from predation and desiccation. The quality of different vegetated and nonvegetated estuarine and rocky shore habitats in SW Portugal and SW England was evaluated for intertidal C. maenas populations. We estimated population density, size–structure, and potential growth (RNA/DNA ratios) to investigate habitat quality. Vegetated estuarine habitats supported higher crab densities, than nonvegetated estuarine and rocky shore habitats. Investigation of population size–structure revealed that all habitats seem important recruitment and nursery areas although estuarine habitats in SW Portugal appeared to support higher densities of new recruits than equivalent habitats in SW England. Significant variation was found in RNA/DNA ratios among habitats. Ratios were highest in the rocky shore suggesting a high quality habitat where growth potential is high. We speculate that competition from other top-predators (Pachygrapsus spp.) rather than low habitat quality may limit the occurrence of C. maenas in intertidal rocky shore habitats in SW Portugal. In estuarine environments RNA/DNA ratios were significantly higher in the vegetated than in the nonvegetated estuarine habitats in SW Portugal but not in SW England, suggesting geographic differences in the extent to which highly structure habitats represent high quality. Our results challenge the current paradigm that structured habitats are necessarily those of higher quality for C. maenas.     

不同光源及光照时间对凡纳滨对虾生长的影响

以黑暗条件作为对照,研究了白炽灯、日光灯、金卤灯作为照明光源及不同光照时间对凡纳滨对虾(Litopenaeusvannamei)生长的影响。实验对虾初始平均质量为2.108g±0.036g(均值±标准误),投喂的饲料为海跃牌全价人工配合饲料,实验持续50d。结果表明:(1)凡纳滨对虾在金卤灯照明的条件下生长最快(P<0.05),在日光灯的连续照明下生长最慢(P<0.05),在其他的光照条件下与黑暗对照的情况下其生长没有显著差异(P>0.05)。其中,金卤灯照明条件下凡纳滨对虾的特定生长率比日光灯连续照明时要快55.89%。(2)具昼夜节律日光灯、15W白炽灯照明及15W连续照明的条件下,凡纳滨对虾的摄食率与黑暗对照组无显著差异(P>0.05),在日光灯连续照明时其摄食率显著低于黑暗对照组(P<0.05),在200W白炽灯及金卤灯照明时凡纳滨对虾摄食率显著高于黑暗对照组(P<0.05),但黑暗对照组的摄食率并不是零;说明视觉虽不是凡纳滨对虾主要觅食手段,但视觉是其辅助觅食手段。(3)在具昼夜节律低功率白炽灯照明、高功率白炽灯及日光灯持续照明的条件下,凡纳滨对虾的食物转化率较低(P<0.05)。其他光照条件下凡纳滨对虾的食物转化率与黑暗对照无显著差异(P>0.05),但以金卤灯照明条件下食物转化率最高。(4)研究表明,凡纳滨对虾在金卤灯照明时具有较高的生长速度缘于其较高的摄食率和食物转化率;在日光灯持续照明的条件下,凡纳滨对虾的摄食率和食物转化率均较低,因而此条件下凡纳滨对虾生长得较慢。因此,进行对虾室内养殖时,金卤灯是首先的照明光源,而日光灯作为照明光源是不适宜的。     

Transport and accumulation of organochlorines in the ovaries of Atlantic croaker (Micropogonias undulatus)

The role of vitellogenin in the transport of organochlorines was investigated in Atlantic croaker (Micropogonias undulatus) by exposing them through the diet to o,p′-DDT at a concentration of 10.8 μg/100 g fish/day for 14 days or Aroclor 1254 (PCB) at a concentration of 0.5 mg/100 g fish/day for 30 days during gonadal recrudescence. Tissue samples were taken from the fish at various times after initial exposure, and o,p′-DDT and PCBs were extracted in acetonitrile and analyzed by gas chromatography. Analysis of the ovarian tissue collected 2 and 3 weeks from the start of exposure revealed that the o,p′-DDT concentration increases as the gonadosomatic index (GSI) increases (r² = 0.63), with accumulation ranging from less than 1% to as much as 8% of the total dosage. Interestingly, o,p′-DDT did not accumulate in the testes during the same exposure period. Accumulation of PCBs was found to be 40 times higher in the ovaries than in the testes. Gel filtration of plasma from exposed females showed that o,p′-DDT elutes in the low density lipoprotein and vitellogenin fractions. Control plasma incubated with o,p′-DDT at 4 °C for 16 h followed by chromatography on Sepharose 6B gave similar results with an o,p′-DDT concentration of 0.6μg/mg protein in the vitellogenin fraction. Furthermore, both o,p′-DDT and PCBs were found to bind to purified croaker vitellogenin. These results suggest that lipoproteins, including vitellogenin, are involved in the transport and accumulation of organochlorines in the ovaries of exposed fish.     

日本囊对虾Marsupenaeus japonicus)组织蛋白酶D基因克隆及表达分析

组织蛋白酶D是溶酶体天冬氨酸蛋白酶家族的主要成员,广泛参与动物机体细胞内蛋白质的降解过程,对维持细胞稳态和正常代谢具有重要的作用。为研究组织蛋白酶D在甲壳动物非特异性免疫和幼体发育过程中的作用,本研究采用RACE技术首次克隆得到日本囊对虾组织蛋白酶D基因cDNA序列,命名为MjCatD,其中开放阅读框长为1161 bp,编码386个氨基酸残基。序列分析和同源建模显示该基因编码的蛋白含有保守的N-糖基化位点、天冬氨酸蛋白酶签名序列、酶活化位点和非消化性组织蛋白酶D的特征序列,并且呈保守的双叶形结构。同源性比较和系统进化分析发现,MjCatD与斑节对虾、美洲螯龙虾和脊尾白虾相似性较高,并且与它们紧密聚为一支。实时荧光定量PCR结果显示,MjCatD基因在日本囊对虾多个组织中均有表达,其中肝胰腺中表达量最高。在白斑综合征病毒(white spot syndrome virus, WSSV)感染后3～24 h日本囊对虾肝胰腺中MjCatD的表达量逐渐下降,而在48 h急剧上调至最高表达量并且与对照组差异极显著(P<0.01)。此外,MjCatD基因在幼体发育不同阶段中也表现出明显的变化趋势。以上研究表明,MjCatD基因可能参与日本囊对虾先天免疫反应和幼体发育过程。     

Effect of crab size and habitat type on the locomotory activity of juvenile shore crabs, Carcinus maenas

Post-settlement processes are a major focus in the study of the dynamics of marine populations and communities. Post-settlement movement of juveniles is an important, but often ignored, process which affects local predator–prey and competitive interactions. We used benthic suction sampling and pitfall traps to examine density and locomotory activity of Carcinus maenas juveniles in different intertidal habitat types in the Rio Mira Estuary, Portugal, to better understand intra-specific interactions in a system where density-dependent processes are known to regulate population dynamics. As expected, significantly higher densities of juvenile shore crabs were found from bare mud compared to densely vegetated habitats. At the time of sampling, small and intermediate stages together outnumbered by far the larger juveniles. Conversely, larger crabs were much more frequent than smaller ones in traps. A locomotory index (LI), i.e. the ratio between crab catch in pitfall traps and their density within their moving range, is proposed as a measure of movement. LI analyses indicated that: (1) movement is an order of magnitude higher in large than small juveniles and much higher in sparse than dense vegetation cover; (2) activity of small juveniles is mostly crepuscular, regardless of vegetation cover; and (3) movement of large juveniles is very limited in dense Zostera patches, but very high in sparsely vegetated areas, during the day and night. These results suggest that small juveniles are relatively protected under dense vegetation cover due to lower mobility of larger crabs, and provide evidence of temporal segregation of activity windows between juvenile crabs of different sizes, which may be a key mechanism to reduce cannibalism and therefore increase the carrying capacity of nursery habitats.     

Differences in the effects of mercury on predator avoidance in two populations of the grass shrimp Palaemonetes pugio

Adult Palaemonetes pugio were collected from two tidal creek systems, Piles Creek (PC), a mercury polluted estuary, and Big Sheepshead Creek (BSC), a relatively pristine creek. Adult killifish (Fundulus heteroclitus), a natural predator of P. pugio, were obtained from BSC. For each test, ten treated (0·01 mg/liter mercuric chloride (HgCl), or 0·01 mg/liter methylmercuric chloride (MeHg)), or control shrimp here introduced into a tank containing three fish. The time between capture of the first and second BSC HgCl treated shrimp was significantly faster (P < 0·05), as was the time between the first and second capture (P < 0·05) of MeHg treated BSC shrimp when compared with their respective controls. In addition, significantly more (P < 0·025) BSC HgCl treated shrimp were captured after 120 min. No significant difference existed between control and HgCl treated PC shrimp; however, significantly more PC MeHg treated shrimp were captured after 60 (P < 0·05) min when compared with their respective controls. These data suggest that PC shrimp, subjected to mercury in their natural environment, are more tolerant to the sublethal effects of both HgCl and MeHg. These data also suggest that behavioral studies can be very sensitive assays for determining the effects of sublethal concentrations of toxicants on populations of organisms.     

Nursery areas of red mullet (Mullus barbatus), hake (Merluccius merluccius) and deep-water rose shrimp (Parapenaeus longirostris) in the Eastern-Central Mediterranean Sea

The spatial pattern of the nursery areas of red mullet (Mullus barbatus), hake (Merluccius merluccius) (Linnaeus, 1758) and deep-water rose shrimp (Parapenaeus longirostris) (Lucas, 1846) was studied in the South Adriatic and North Ionian Seas (Eastern-Central Mediterranean) applying geostatistical techniques and data from time series trawl surveys conducted in the area. The analysed variables were: R (number of recruits/km²) and R/Tot (fraction of recruits on the total sampled population). The structural analysis showed a spatial pattern of both variables characterized by continuity on a small scale. Predictions of nursery area localization with probability of finding recruits at different threshold values were obtained through median indicator kriging. For the red mullet the nurseries were mainly identified in the South Adriatic Sea off the Gargano peninsula and between Molfetta and Monopoli within 50 m in depth. The main concentration of hake juveniles was found to be between 100 and 200 m in depth along the Gargano peninsula and between Otranto and Santa Maria di Leuca, where a nursery of deep-water rose shrimp was also detected. An overlapping depth, between 100 and 200 m, was identified for hake and deep-water rose shrimp nurseries. Protection of these areas through limitations of fishing pressure is discussed.     

Altered glutathione status in atlantic croaker (Micropogonias undulatus) tissues exposed to lead

Metals which induce the synthesis of metallothioneins, such as cadmium and mercury, also elevate glutathione (GSH) concentrations in fish tissues.^1,2 To determine whether metals which do not stimulate metallothionein synthesis increase GSH levels, the GSH status of Atlantic croaker tissues was examined after oral administration of lead. Lead significantly increased GSH levels in the intestine and liver, but not in kidney or brain tissues. Lead was not bound to GSH and the increase in GSH did not appear to be linked to lead accumulation in these tissues. Investigations of hepatic GSH synthesis and turnover in vitro using a radiolabelled amino acid precursor, C¹⁴ glycine, showed that the elevation of GSH was due to an increase in GSH synthesis rather than decreased utilization of GSH. These studies suggest that the interactions between GSH and lead are indirect and involve a stimulatory effect of the metal on the activity of the enzymes for GSH synthesis.     

The effect of standing biomass on flow velocity and turbulence in Spartina alterniflora canopies

Plant-flow interactions on the surface of tidal wetlands result in flow characteristics that are profoundly different from non-vegetated flows. Reductions in mean flow velocity and turbulence, especially the vertical components, limit vertical mixing and may impact a wide range of processes including geochemical exchanges at the sediment water interface, larval recruitment and dispersion, and sediment deposition and retention. The goal of this paper is to quantify horizontal and vertical components of velocity, turbulence intensity and total turbulent kinetic energy in Spartina alterniflora canopies in southeastern North Carolina and to relate flow characteristics to particulate transport on the marsh surface. Another aim of this paper is to assess the extent to which the distribution of standing biomass affects mean flow and turbulence by comparing S. alterniflora data to other canopy types and through a series of canopy manipulations which altered canopy height and stem densities.The results of this study indicate that flow velocity, turbulence intensity, and total turbulent kinetic energy (TKE) are significantly reduced within the vegetated canopy and that this reduction is inversely related to the amount of biomass present in the water column. Within the canopy, approximately 50% of the initial mean velocity and TKE is reduced within 5 m of the canopy edge. Within the canopy, mean velocity and TKE_horiz usually exceeded vertical velocity or TKE_vert and the vertical components of flow were attenuated more strongly than the horizontal. These results suggest that within the vegetation, turbulence contributes more to lateral advection than to vertical mixing. As a result, total suspended solid concentrations were shown to decrease logarithmically with distance from the canopy edge and to decrease at a faster rate in more densely vegetated regions of the canopy (i.e. lower TKE_vert) as compared to areas of sparser vegetation (i.e. higher TKE_vert).     

中华原钩虾(Eogammarus possjeticus)对浒苔(Ulva prolifera)及其他类型饵料的摄食研究

采用生理生态学方法,研究了中华原钩虾(Eogammaruspossjeticus)对黄海绿潮原因种浒苔(Ulva prolifera)及海水池塘4种优势大型海藻,即肠浒苔(Ulva intestinalis)、扁浒苔(Ulva compressa)、线形硬毛藻(Chaetomorphalinum)和丝毛藻(Cloniophorasp.)的摄食率,比较了对浒苔与其他不同类型饵料(包括人工饵料)的摄食,开展了不同密度的中华原钩虾对浒苔的现场摄食研究。结果显示,中华原钩虾的摄食率、饵料吸收率与海藻的含水量成呈正相关,表明该端足类存在明显的补偿性摄食行为。对不同类型饵料的摄食结果显示,中华原钩虾除了摄食海藻,对豆粕、虾饲料等人工饵料也具有较高的饵料吸收率,表明其可人工投喂培育。中华原钩虾具有一定摄食节律,夜晚摄食量高于白昼,表明夜晚投喂有利于中华原钩虾摄食,可减少饵料污染,有利于清洁生产。现场摄食实验结果显示,中华原钩虾摄食量随养殖密度的增加而增加,但其摄食率和存活率与养殖密度呈负相关,表明高密度时中华原钩虾竞争摄食增加了饵料消耗,同时中华原钩虾为抵抗养殖密度过高造成的竞争而增加能量等消耗。     

低盐胁迫对大黄鱼非特异性免疫酶活力的影响

以大黄鱼（Larimichthys crocea）为研究对象,研究急性、慢性低盐度胁迫对大黄鱼存活状况及非特异性免疫酶活力的影响。结果表明：急性低盐（15、8）胁迫下,在7 d的实验周期中,大黄鱼肝脏的超氧化物歧化酶（superoxide dismutase, SOD）活力呈先上升后下降的趋势,在第1天显著上升（p<0.05）后逐渐下降至显著低于对照组水平;肝脏的过氧化氢酶（catalase, CAT）活力整体呈先下降后上升再下降的趋势,在第1天显著下降后开始升高,第3天后开始下降,至第7天时CAT活力仍显著低于对照组水平;血清中的酸性磷酸酶（acid phosphatase, ACP）活力呈下降后逐渐升高的趋势,在第1 天时显著下降后逐步升高,至第7天时仍显著低于对照组;而血清中的碱性磷酸酶（alkaline phosphatase, ALP）活力在实验开始的第1天到第3天逐渐升高,且均显著高于对照组,至第7天时开始下降至对照组水平;血清中的溶菌酶（lysozyme, LZM）含量呈波动变化,整体呈先上升后下降趋势。慢性低盐（8）养殖14 d后,大黄鱼的各项非特异性免疫酶活力均与对照组无显著性差异（p>0.05）。此外,实验周期内所有组别大黄鱼均未出现死亡,仅急性低盐胁迫组大黄鱼的活动和摄食受到有限影响。大黄鱼对慢性降盐度养殖有较高的耐受能力,而盐度骤降会显著影响大黄鱼的非特异性免疫,实际生产中应避免养殖环境盐度的剧烈变化。     

Benthic macrofauna–habitat associations in Willapa Bay, Washington, USA

Estuary-wide benthic macrofauna–habitat associations in Willapa Bay, Washington, United States, were determined for 4 habitats (eelgrass [Zostera marina], Atlantic cordgrass [Spartina alterniflora], mud shrimp [Upogebia pugettensis], ghost shrimp [Neotrypaea californiensis]) in 1996 and 7 habitats (eelgrass, Atlantic cordgrass, mud shrimp, ghost shrimp, oyster [Crassostrea gigas], bare mud/sand, subtidal) in 1998. Most benthic macrofaunal species inhabited multiple habitats; however, 2 dominants, a fanworm, Manayunkia aestuarina, in Spartina, and a sand dollar, Dendraster excentricus, in subtidal, were rare or absent in all other habitats. Benthic macrofaunal Bray–Curtis similarity varied among all habitats except eelgrass and oyster. There were significant differences among habitats within- and between-years on several of the following ecological indicators: mean number of species (S), abundance (A), biomass (B), abundance of deposit (AD), suspension (AS), and facultative (AF) feeders, Swartz's index (SI), Brillouin's index (H), and jackknife estimates of habitat species richness (HSR). In the 4 habitats sampled in both years, A was about 2.5× greater in 1996 (a La Niña year) than 1998 (a strong El Niño year) yet relative values of S, A, B, AD, AS, SI, and H among the habitats were not significantly different, indicating strong benthic macrofauna–habitat associations despite considerable climatic and environmental variability. In general, the rank order of habitats on indicators associated with high diversity and productivity (high S, A, B, SI, H, HSR) was eelgrass = oyster ≥ Atlantic cordgrass ≥ mud shrimp ≥ bare mud/sand ≥ ghost shrimp = subtidal. Vegetation, burrowing shrimp, and oyster density and sediment %silt + clay and %total organic carbon were generally poor, temporally inconsistent predictors of ecological indicator variability within habitats. The benthic macrofauna–habitat associations in this study can be used to help identify critical habitats, prioritize habitats for environmental protection, index habitat suitability, assess habitat equivalency, and as habitat value criteria in ecological risk assessments in Willapa Bay.     

Heterosis and heritability estimates for the survival of the Pacific white shrimp (Litopenaeus vannamei) under the commercial scale ponds

The aim of the present study is to detect the potential of the base population from diallel crosses of eight introduced strains of the Pacific white shrimp(Litopenaeus vannamei) for improving the yield. Heterosis and heritability were estimated for pond survival at commercial farm conditions for the base population that included 207 full-sib families from a nested mating design by artificial insemination. Among all the hybrids,the heterosis ranged from –11.37%(UA1×UA2) to 20.53%(UA3×SIN) with an average of 0.953%. The results showed that more than half of the hybrids(51.85%) have negative heterosis for survival rate, but most of the hybrids with positive heterosis have high estimates. The high proportion of negative heterosis for survival rate reminders us that the survival trait also should be considered in the crossbreeding program to avoid yield decrease. However, high positive heterosis manifested in most of the hybrids for survival indicates the usefulness of these hybrids for improving the survival to obtain higher yield by crossbreeding in this breeding program. The heritability estimate for pond survival was 0.092±0.043 when genetic groups were included in the pedigree, and it was significantly different from zero(P0.05). The results from this study also indicated that significant improvement for survival is possible through selection in L. vannamei.     

不同底质对方斑东风螺生长及存活的影响

比较了自然沙、棕色陶粒、白色陶粒、70%棕色陶粒+30%贝壳砂、贝壳砂等5种底质材料及空白对照组(无底质),对体质量为0.193 g±0.03 g的方斑东风螺生长、存活、摄食以及培育过程中水质的影响。结果表明,白色陶粒组的存活率为80%,显著低于其他各组(P0.05);棕色陶粒组的体质量特定生长率最高(4.31%/d),且显著优于白色陶粒组和对照组(P0.05);棕色陶粒处理组方斑东风螺的饵料转化效率显著高于白色陶粒组和空白对照组;水质中总氨氮、亚硝酸氮和COD均呈上升趋势,各组之间差异不显著。     

密度胁迫对日本囊对虾生长和水环境的影响

为了探讨密度胁迫对日本囊对虾(Marsupenaeus japonicus)生长、存活及水质因子的影响, 作者设置了100尾/m²(DD)、200 尾/m²(GD)、400 尾/m²(GZ)、600 尾/m²(GG)4个养殖密度, 分析了不同养殖密度下日本囊对虾的生长量、存活率、肥满度及水质因子的差异。结果表明, 实验所监测的水质因子均在对虾生长的安全阈值内, 氨态氮、亚硝态氮、总氮和总磷含量表现出随养殖密度增加逐渐升高的趋势; 体长和体质量增长量、存活率与养殖密度呈负相关, 其中存活率处理间均达到极显著水平(P< 0.01), 且当养殖密度高于200尾/m²时存活率迅速降低; 低养殖密度(DD)处理的对虾肥满度与其他处理间差异均达到显著水平(P< 0.01)。因此, 在相似养殖条件下, 日本囊对虾的适宜养殖密度应该不高于200尾/m²。本实验过程中, 各处理间水质因子均在对虾生长的适宜范围内, 说明水质不是造成对虾死亡的主要原因。所以, 推测密度胁迫可能是造成日本囊对虾存活率低的主要原因。     

中国明对虾(Fenneropenaeus chinensis)丝氨酸蛋白酶同源物基因(Fc-SPH)的重组表达及活性分析

以实验室前期克隆到的中国明对虾丝氨酸蛋白酶同源物基因(Fc-SPH)(GenBank登录号:DQ318859)为基础,利用原核表达系统对Fc-SPH基因成熟肽区域进行了重组表达和纯化复性分析,并对获得的重组目的蛋白开展了抑菌活性及微生物清除功能研究。结果表明:在体外成功获得了大量有活性的对虾Fc-SPH蛋白(rFc-SPH),活性研究显示rFc-SPH对大多数受试菌种都有明显的抑制效果,并可以加速中国明对虾清除体内外源微生物的速度。作者推断Fc-SPH即可以作为一线防御应答效应物直接参与虾类的先天免疫活动而发挥作用,也可以通过调理作用促进血细胞对病原微生物的吞噬和杀灭。     

牙鲆gnrh基因的表达分析

本文通过qPCR方法,研究了我国重要海水鱼类——牙鲆（Paralichthys olivaceus）雌、雄成体组织以及性腺分化期的脑、性腺中gnrh1、gnrh2和gnrh3的表达水平。结果显示,gnrh1分布于所有检测的组织：在脑、垂体、肾脏和肝脏中高表达,在性腺中表达相对较低;gnrh2则在雌、雄性的肝脏以及雄性的肠、肾脏、眼睛和头肾中;而gnrh3只在雄性的肾脏、眼睛和肌肉中检测到微弱表达。人工诱导的牙鲆雌核发育鱼苗分别用17β-雌二醇（E₂）和17α-甲基睾酮（MT）处理,使其分化为雌性或雄性个体表型。在性腺分化期的脑中,gnrh1的表达呈现上升趋势,在全长（total length,TL）4 cm鱼苗中,E₂组的表达显著高于MT组（P<0.05）;gnrh2在2 cm TL时E₂组显著高于MT组（P<0.05）,随后在E₂和对照组的表达水平均出现下降趋势;gnrh3在2 cm TL时E₂和对照组的表达均显著高于MT组（P<0.05）,自6 cm TL时MT和E₂组的表达开始下降。在性腺中,三种gnrh在性腺分化前2 cm TL表达量都相对较高,随后呈现下降趋势。综上,推测牙鲆gnrh1可能参与了性腺分化的启动、分化过程及性腺发育,gnrh2主要参与了性腺分化的启动,gnrh3主要参与了性腺分化的启动和分化过程。