Cumulative selectivity benefits of increasing mesh size and using escape gaps in Australian Portunus armatus traps

The individual and cumulative effects of increasing mesh size (from 56‐ to 75‐mm stretched mesh opening) and installing three escape gaps (36 × 120 mm) in collapsible‐netted round traps were assessed to address concerns associated with excessive discarding in an Australian portunid fishery. Compared to conventional traps comprising 56‐mm mesh throughout, those with the same mesh size and escape gaps caught significantly fewer (by 54%) undersized blue swimmer crabs, Portunus armatus Milne‐Edwards and yellowfin bream, Acanthopagrus australis Günther (by 64%). Irrespective of escape gaps, simply increasing the mesh size to 75 mm did not significantly affect catches of undersized P. armatus, although 87% fewer A. australis were retained. Traps with both 75‐mm mesh and escape gaps maintained reductions of A. australis, but had a clear cumulative effect on P. armatus selection, retaining 84% fewer undersized individuals across a larger size at retention. The results support using escape gaps in existing conventional traps, but illustrate the need to configure the minimum legal mesh size to approach the desired target size of P. armatus as a precursor to maximising trap selectivity. Larger‐meshed traps also require less material (i.e. plastic), which benefits their manufacture and, equally importantly, reduces environmental costs when lost.     

Spatial and temporal distribution of Lepeophtheirus salmonis (Kr?yer) larvae in a sea loch containing Atlantic salmon, Salmo salar L., farms on the north-west coast of Scotland.

A plankton survey investigated spatial and temporal distributions of larval sea lice in a sea loch on the north-west coast of Scotland. Plankton tows were collected approximately weekly at two depths (0 and 5 m) at five sample stations over a 2-year period. The survey began in March 2002 when Atlantic salmon, Salmo salar L., farms in the study area stocked with fish and finished in March 2004, after farms completed harvesting. Over 90% of lice recovered were Lepeophtheirus salmonis (Kr?yer); therefore, the results of this paper refer largely to that species. The data were analysed using generalized additive models with explanatory variables for time, depth and station. Greatest densities of nauplii were recovered at stations adjacent to farms indicating that the local salmon farms were a likely source of larvae at times during the production cycle. There were significant temporal trends in larval densities and the stocking and harvesting of farms can possibly account for these increases and decreases, particularly at the start and at the end of the production cycle. The distribution of copepodids was more widespread than that of nauplii, indicating that the larvae can be transported several kilometres from the point of release.     

Immunization of BALB/c mice with DNA encoding equine herpesvirus 1 (EHV-1) glycoprotein D affords partial protection in a model of EHV-1-induced abortion

DNA-mediated immunization was assessed in a murine model of equine herpesvirus 1 (EHV-1) abortion. Whilst there are differences between the model and natural infection in the horse, literature suggests that EHV-1 infection of pregnant mice can be used to assess the potential ability of vaccine candidates to protect against abortion. Female BALB/c mice were inoculated twice, 4 weeks apart, with an expression vector encoding EHV-1 glycoprotein D (gD DNA). They were mated 15 days after the second inoculation, challenged at day 15 of pregnancy and killed 3 days later. The gD DNA-inoculated mice had fewer foetuses which were damaged or had died in utero (6% in gD DNA, 21% vector DNA and 28% in nil inoculated groups challenged with EHV-1), a reduction in the stunting effect of EHV-1 infection on foetuses (gD DNA: 0.40g+/-0.06, vector DNA: 0.34g+/-0.10), reduced placental and herpesvirus-specific lung histopathology and a lower titre of virus (TCID(50)+/-SEM/lung) in maternal lung than control groups (gD DNA 4.7+/-0.3, vector 5.3+/-0.2, nil 5.6+/-0.2). Maternal antibody to EHV-1 gD was demonstrated in pups born to a dam inoculated 123 days earlier with gD DNA. Although protection from abortion was incomplete, immunization of mice with gD DNA demonstrated encouragingly the potential of this vaccine strategy.     

内蒙古阿拉善荒漠啮齿动物群落结构及其多样性研究

对内蒙古阿拉善荒漠区啮齿动物群落结构和多样性进行了研究。依据样地种多度(捕获率)聚类方法,并结合生境中地带性植被类型的综合特征,该荒漠区啮齿动物可划分为6个地带性群落。Ⅰ.小毛足鼠(Phodopus roborovskii)+三趾跳鼠(Dipus sagitta)+子午沙鼠(Meriones meridianus)群落。Ⅱ.长尾仓鼠(Cricetulus longicaudatus)+大林姬鼠(Apodemus speciosus)群落。Ⅲ.五趾跳鼠(Allactaga sibirica)+子午沙鼠(Meriones meridianus)+三趾跳鼠(Dipus sagitta)群落。Ⅳ.三趾跳鼠(Dipus sagitta)+小毛足鼠(Phodopus roborovskii)+子午沙鼠(Meriones meridianus)群落。Ⅴ.长耳跳鼠(Euchoreutes naso)+五趾跳鼠(Allactaga sibirica)群落。Ⅵ.子午沙鼠(Meriones meridianus)+黑线仓鼠(Cricetulus barabensis)群落。其中群落Ⅲ多样性指数最高,为2.0557;群落I与群落IV的相似性系数最大,为0.5147;群落Ⅲ具有代表性。该荒漠区啮齿类数量与生境中的土壤水分、土壤基质呈显著正相关;与建群植物种数呈显著负相关;而与生境的海拔高度相关性极低。     

DNA base composition of rickettsiae

There is a small but distinct difference in DNA base composition between the typhus and spotted fever groups of rickettsiae. The molar percentages of guanine plus cytosine for Rickettsia prowazeki, R. typhi, and R. canada are approximately 30, for R. rickettsi, R. conori, and R. akari they are about 32.5. The percentage for trench fever rickettsia, Rochalimaea quintana, is 38.6.     

Depolarization- and ionophore-induced release of octacosa somatostatin from stalk median eminence synaptosomes

Species of somatostatin of higher molecular weight were present in the nerve terminals (synaptosomes) of ovine stalk median eminences and were released by depolarizing stimuli. One of these species was identified as the biologically active molecule octacosa somatostatin. Octacosa somatostatin appears therefore to be secreted into the hypothalamic-hypophyseal system, supporting the concept of a role for this peptide in regulating pituitary hormone secretion.