Moulting frequency and behavioural responses to salinity and diesel oil in Austromegabalanus psittacus (Molina) (Cirripedia: Balanidae)

Moulting frequency and behavioural responses to salinity and diesel oil concentration were studied in specimens of the giant barnacle Austromegabalanus psittacus (Molina). Moulting frequency and frequency and type of cirral beat, in addition to opercular valve closure time, were measured under controlled conditions. A binary factorial experimental design was carried out at salinities of 20 and 30‰ and diesel oil concentrations of 0.1 and 0.5% v/v. Moulting frequency was greater at 30‰ than at 20‰ salinity and at 0.1% oil concentration than at both 0.5% oil concentration and in controls; it is unlikely that this signified variations in growth. Diesel oil provoked lethal effects at 0.5%, with an average lethal time of 8 days; at 0.1%, only sublethal effects were generated. Cirral beat frequency was greater at 0.1 and 0.5% diesel oil concentration than in controls. This was probably associated with an increase in metabolism, since the most frequent cirral beats are associated with respiration and the active capture of plankton. The effects of the contaminant varied with time, as observed at 15 and 60 min. The opercular valve closure time was longer in controls and decreased as diesel oil concentration increased. Results suggest that this species is highly resistant to pollution, although contaminants could provoke changes in the feeding and growth of specimens. Local variations in salinity have only minor effects on barnacle behaviour.     

Relative tolerance of cirripede larval stages to acute thermal shock: A laboratory study

(1) Meroplankters drawn into once-through cooling circuits of coastal power plants are subjected to transient thermal stress. The effect of such acute thermal shock on the development of barnacle larvae was studied in the laboratory.

(2) The response of the barnacle larvae (naupliar and cyprid stages) to elevated temperature was dependent on exposure time and their stage of development.

(3) Among the stages tested, N-6 larvae showed maximum tolerance. Exposure to 37°C did not affect larval survival, but delayed development of N-2 larva to cypris by one day.

(4) Exposure at 40°C delayed, hastened or did not affect the development time of N-2 and N-4 larvae through cypris, depending on exposure time.

(5) Ten mins exposure at 43°C proved lethal to all larval stages with mortality ranging from 20 to 86%.

(6) Development success of the surviving larvae, measured in terms of cypris yield, showed no significant difference from controls, at temperatures below 40°C.

(7) Settlement activity was significantly affected in only those cyprid larvae which were exposed to 43°C for 10 min.

(8) Results of the present study indicate that thermal stress experienced in the once-through cooling system does not have significant impact on survival and development of the barnacle larvae at temperatures of 37–40°C.     

鹅源腺病毒基因组DNA物理图谱的构建

将鹅源腺病毒Ｙ８１Ｇ４株全基因组ＤＮＡ的ＨｉｎｄⅢ酶切片段分别插入质粒ｐＵＣ１８,成功构建了全基因组ＤＮＡ文库。在此基础上,将重组质粒携带的插入片段切出、回收并分别用地高辛标记后作为探针,与经限制酶ＢａｍＨⅠ、ＥｃｏＲⅠ、ＰｓｔⅠ、ＥｃｏＲⅤ消化的病毒基因组ＤＮＡ进行Ｓｏｕｔｈｅｒｎ Ｂｌｏｔｔｉｎｇ,杂交结果经比较综合后获得了该病毒基因组ＤＮＡ的ＨｉｎｄⅢ、ＢａｍＨⅠ、ＥｃｏＲⅠ、ＰｓｔⅠ、Ｅｃ     

Limnological regime shifts caused by climate warming and Lesser Snow Goose population expansion in the western Hudson Bay Lowlands (Manitoba,Canada)

Shallow lakes are dominant features in subarctic and Arctic landscapes and are responsive to multiple stressors, which can lead to rapid changes in limnological regimes with consequences for aquatic resources. We address this theme in the coastal tundra region of Wapusk National Park, western Hudson Bay Lowlands (Canada), where climate has warmed during the past century and the Lesser Snow Goose (LSG; Chen caerulescens caerulescens) population has grown rapidly during the past ~40 years. Integration of limnological and paleolimnological analyses documents profound responses of productivity, nutrient cycling, and aquatic habitat to warming at three ponds (“WAP 12”, “WAP 20”, and “WAP 21″), and to LSG disturbance at the two ponds located in an active nesting area (WAP 20, WAP 21). Based on multiparameter analysis of ²¹⁰Pb‐dated sediment records from all three ponds, a regime shift occurred between 1875 and 1900 CE marked by a transition from low productivity, turbid, and nutrient‐poor conditions of the Little Ice Age to conditions of higher productivity, lower nitrogen availability, and the development of benthic biofilm habitat as a result of climate warming. Beginning in the mid‐1970s, sediment records from WAP 20 and WAP 21 reveal a second regime shift characterized by accelerated productivity and increased nitrogen availability. Coupled with 3 years of limnological data, results suggest that increased productivity at WAP 20 and WAP 21 led to atmospheric CO₂ invasion to meet algal photosynthetic demand. This limnological regime shift is attributed to an increase in the supply of catchment‐derived nutrients from the arrival of LSG and their subsequent disturbance to the landscape. Collectively, findings discriminate the consequences of warming and LSG disturbance on tundra ponds from which we identify a suite of sensitive limnological and paleolimnological measures that can be utilized to inform aquatic ecosystem monitoring.     

Perceptions towards Egyptian Geese at the Steenberg Golf Estate,Cape Town,South Africa

The number of Egyptian Geese Alopochen aegyptiaca has increased in the Western Cape province, South Africa, during the past few decades and they are allegedly perceived as a problem on golf courses. However, attitudes towards the geese on golf courses in the province have not been empirically assessed. We surveyed the residents and members of the Steenberg Golf Estate, Cape Town, during April 2012 to evaluate perceptions towards Egyptian Geese on the estate. A standardised, anonymous questionnaire was sent to 548 estate residents and non-resident golfing members. Of the 112 respondents, the majority (92, or 84%) considered that geese are a problem on the estate. The ranking of the perceived problem was: 16 (15%) minimal problem, 34 (33%) moderate problem and 54 (52%) severe problem. The majority also considered that the goose population should be reduced by 50% or more (90, or 86% of all respondents). Dealing with Egyptian Geese numbers and activities on golf courses is complex. The option of designing golf courses and adjacent vegetation so that they are attractive to local bird species, while simultaneously being less attractive to Egyptian Geese, is available.     

Goose parvovirus structural proteins expressed by recombinant baculoviruses self-assemble into virus-like particles with strong immunogenicity in goose

Goose parvovirus (GPV), a small non-enveloped ssDNA virus, can cause Derzsy’s disease, and three capsid proteins of VP1, VP2, and VP3 are encoded by an overlapping nucleotide sequence. However, little is known on whether recombinant viral proteins (VPs) could spontaneously assemble into virus-like particles (VLPs) in insect cells and whether these VLPs could retain their immunoreactivity and immunogenicity in susceptible geese. To address these issues, genes for these GPV VPs were amplified by PCR, and the recombinant VPs proteins were expressed in insect cells using a baculovirus expression system for the characterization of their structures, immunoreactivity, and immunogenicity. The rVP1, rVP2, and rVP3 expressed in Sf9 cells were detected by anti-GPV sera, anti-VP3 sera, and anti-His antibodies, respectively. Electron microscopy revealed that these rVPs spontaneously assembled into VLPs in insect cells, similar to that of the purified wild-type GPV virions. In addition, vaccination with individual types of VLPs, particularly with the rVP2-VLPs, induced higher titers of antibodies and neutralized different strains of GPVs in primary goose and duck embryo fibroblast cells in vitro. These data indicated that these VLPs retained immunoreactivity and had strong immunogenicity in susceptible geese. Therefore, our findings may provide a framework for development of new vaccines for the prevention of Derzsy’s disease and vehicles for the delivery of drugs.     

Flow cytometric assessment of fresh and frozen-thawed Canada goose (Branta canadensis) semen

The present study was conducted to investigate spermatozoal membrane integrity, acrosome integrity, mitochondrial activity, and chromatin structure in fresh and frozen-thawed Canada goose (Branta canadensis) semen with the use of the flow cytometry. The experiment was carried out on ten, 2-year-old, Canada goose ganders. The semen was collected twice a week, by a dorso-abdominal massage method, then pooled and subjected to cryopreservation in straws, in a programmable freezing unit with the use of dimethyloformamide (DMF) as a cryoprotectant. Frozen samples were thawed in a water bath at 60 °C. The freezing procedure was performed ten times. For the cytometric analysis the fresh and the frozen-thawed semen was extended with EK extender to a final concentration of 50 million spermatozoa per mL. Sperm membrane integrity was assessed with SYBR-14 and propidium iodide (PI), acrosomal damage was evaluated with the use of PNA-Alexa Fluor^®488 conjugate, mitochondrial activity was estimated with Rhodamine 123 (R123), and spermatozoal DNA integrity was measured by the sperm chromatin structure assay (SCSA). The cryopreservation of Canada goose semen significantly decreased the percentage of live cells, from 76.3 to 50.4% (P < 0.01). Moreover, we observed the significant decrease in the percentage of live spermatozoa with intact acrosomes (P < 0.01), but we did not detect significant changes in the percentage of live spermatozoa with ruptured acrosomes. However, after thawing 50% of Canada goose live spermatozoa retained intact acrosomes. Furthermore, the percentage of live spermatozoa with active mitochondria was significantly lower in the frozen-thawed semen than in the fresh semen (P < 0.05). Nevertheless, after thawing the mitochondria remained active in almost 50% of live cells. In the present study, we observed no changes in the percentage of sperm with fragmented DNA after freezing-thawing of Canada goose semen. In conclusion, the present study indicates that even the fresh Branta canadensis semen might have poor quality, the cryopreservation of its semen did not provoke spermatozoal DNA defragmentation and half of the spermatozoa retained intact acrosomes and active mitochondria after freezing-thawing.     

Genetic diversity of local geese of varying productivity and feather color in Kars

The local geese in the transition region between the Caucasus Mountains and Anatolia have economically significant differences in productivity and are identified by four feather colors, white, black, piebald, and yellow. This study was undertaken to determine the genetic structure, evolutionary relationships, and genetic diversity among these birds. DNA samples were obtained from 100 animals, and 50 random primers were screened. Genetic relationships were determined by random amplified polymorphic DNA polymorphisms obtained from a total of 48 loci, showing 40 bands (83.33%) that were polymorphic among all the populations investigated. A dendrogram constructed for this study revealed a close relationship between the white and the black birds. Additionally, the piebald birds showed close similarity to white and black geese, and the yellow birds displayed a clear distance from the other three populations.     

Preferential attachment of barnacle larvae to natural multi-species biofilms: Does surface wettability matter?

We tested the hypothesis that surface wettability does not alter the positive effect of natural biofilms on larval attachment in the barnacle Balanus amphitrite. We also answered the question: Does substratum-biofilm interaction affect the larval choice in barnacle? We developed natural multi-species biofilms of different ages on both high (glass) and low (polystyrene) wettability surfaces at mid-intertidal height (native habitat of B. amphitrite). Attachment choice of both young (0-d-old) and old (6-d-old) larvae to biofilms was determined using still water choice bioassay. Irrespective of larval age, cyprid preferred to attach to un-filmed glass than to un-filmed polystyrene. In contrast to aged larvae, young larvae preferred old (6-d-old) biofilms on polystyrene to young (3-d-old) biofilms on glass. In this study, we were also able to examine the interaction between surface wettability, biofilms and larval attachment, by characterizing bacterial community composition in biofilms. Bacterial community composition showed significant differences between biofilms of different ages. Old biofilms positively influenced larval attachment, irrespective of the type of substrata, thereby supporting the hypothesis that surface wettability does not alter the positive effect of natural biofilms on larval attachment.     

鹅细小病毒分离株HG5／82的分子特征分析

本研究应用PCR技术扩增得到GPV中国分离株HG5/82的非结构基因与结构基因,片段大小分别约为1.9kb、2.2kb的片段。将该片段分别进行克隆及序列测定,并与 GPV 国内外部分已发表的毒株及番鸭细小病毒(Muscovy duck parvovirus,MDPV)的对应序列比较。结果表明:HG5/82 株非结构蛋白(Non structure, NS)基因长为1884bp,编码627个氨基酸。HG5/82株结构蛋白基因长为2199bp,编码732个氨基酸。序列分析结果表明,我国地方分离株与国内外鹅细小病毒相比,ns基因、vp基因均表现出较高的同源性,并且具有共同的分子特征。为进一步研究GPV的基因功能、遗传变化规律及病毒分子致病机理提供了一定的分子基础。结构基因 VP3 间变异较小,这是目前GPV只有一个血清型的分子基础,为基因工程苗的研制提供了可行性。HG5/82 与番鸭细小病毒相应序列比较发现,与细小病毒其它成员相比两者具有较近的亲源关系,但这种同源性明显低于鹅细小病毒之间的同源性。