Effects of different feeding regimes on ovarian maturation and spawning of pond-reared giant tiger prawn in Thailand

Large pond-reared Penaeus monodon were used in three maturation and spawning trials lasting 60 days. One group of prawns was fed a fresh diet only; a second group was supplied a fresh diet combined with a formulated pelleted diet; a third group of prawns received the formulated diet only. Total maturation (N = 66 and 55) and spawning events (N = 63 and 48) were much greater for prawns receiving only the fresh diet, and the combined fresh with formulated diets, respectively. Prawns receiving only the formulated diet matured only 12 times, and spawned 11 times. Prawns fed a fresh diet produced significantly more eggs than those given a formulated diet alone. No significant differences were seen in eggs produced per spawning event, % fertilization, % hatch or % metamorphosis from egg to protozoea. Female prawns exhibited greater mortality than did males, while females on the fresh diet only had greater mortality than did other females, presumably due to greater handling and other stress factors. Female prawns on a combined diet had lower mortality than other females. The formulated diet used is suitable for supplementation, but not as a sole maturation food.     

Pathogenesis of West Nile virus lineage 1 and 2 in experimentally infected large falcons

West Nile virus (WNV) is a zoonotic flavivirus that is transmitted by blood-suckling mosquitoes with birds serving as the primary vertebrate reservoir hosts (enzootic cycle). Some bird species like ravens, raptors and jays are highly susceptible and develop deadly encephalitis while others are infected subclinically only. Birds of prey are highly susceptible and show substantial mortality rates following infection. To investigate the WNV pathogenesis in falcons we inoculated twelve large falcons, 6 birds per group, subcutaneously with viruses belonging to two different lineages (lineage 1 strain NY 99 and lineage 2 strain Austria). Three different infection doses were utilized: low (approx. 500 TCID50), intermediate (approx. 4 log10 TCID50) and high (approx. 6 log10 TCID50). Clinical signs were monitored during the course of the experiments lasting 14 and 21 days. All falcons developed viremia for two weeks and shed virus for almost the same period of time. Using quantitative real-time RT-PCR WNV was detected in blood, in cloacal and oropharyngeal swabs and following euthanasia and necropsy of the animals in a variety of neuronal and extraneuronal organs. Antibodies to WNV were first time detected by ELISA and neutralization assay after 6 days post infection (dpi). Pathological findings consistently included splenomegaly, non-suppurative myocarditis, meningoencephalitis and vasculitis. By immunohistochemistry WNV-antigens were demonstrated intralesionally. These results impressively illustrate the devastating and possibly deadly effects of WNV infection in falcons, independent of the genetic lineage and dose of the challenge virus used. Due to the relatively high virus load and long duration of viremia falcons may also be considered competent WNV amplifying hosts, and thus may play a role in the transmission cycle of this zoonotic virus.     

DNA vaccines encoding the envelope protein of West Nile virus lineages 1 or 2 administered intramuscularly,via electroporation and with recombinant virus protein induce partial protection in large falcons (Falco spp.)

As West Nile virus (WNV) can cause lethal diseases in raptors, a vaccination prophylaxis of free-living and captive populations is desirable. In the absence of vaccines approved for birds, equine vaccines have been used in falcons, but full protection against WNV infection was not achieved. Therefore, two DNA vaccines encoding the ectodomain of the envelope protein of WNV lineages 1 and 2, respectively, were evaluated in 28 large falcons. Four different vaccination protocols were used, including electroporation and booster-injections of recombinant WNV domain III protein, before challenge with the live WNV lineage 1 strain NY99. Drug safety, plasmid shedding and antibody production were monitored during the vaccination period. Serological, virological, histological, immunohistochemical and molecular biological investigations were performed during the challenge trials. Antibody response following vaccination was low overall and lasted for a maximum of three weeks. Plasmid shedding was not detected at any time. Viremia, mortality and levels, but not duration, of oral virus shedding were reduced in all of the groups during the challenge trial compared to the non-vaccinated control group. Likewise, clinical scoring, levels of cloacal virus shedding and viral load in organs were significantly reduced in three vaccination groups. Histopathological findings associated with WNV infections (meningo-encephalitis, myocarditis, and arteritis) were present in all groups, but immunohistochemical detection of the viral antigen was reduced. In conclusion, the vaccines can be used safely in falcons to reduce mortality and clinical signs and to lower the risk of virus transmission due to decreased levels of virus shedding and viremia, but full protection was not achieved in all groups.     

Wolbachia enhance Drosophila stem cell proliferation and target the germline stem cell niche

Wolbachia are widespread maternally transmitted intracellular bacteria that infect most insect species and are able to alter the reproduction of innumerous hosts. The cellular bases of these alterations remain largely unknown. Here, we report that Drosophila mauritiana infected with a native Wolbachia wMau strain produces about four times more eggs than the noninfected counterpart. Wolbachia infection leads to an increase in the mitotic activity of germline stem cells (GSCs), as well as a decrease in programmed cell death in the germarium. Our results suggest that up-regulation of GSC division is mediated by a tropism of Wolbachia for the GSC niche, the cellular microenvironment that supports GSCs.     

Studies of chlorophyll-lipid-water systems

Preliminary studies of the electronic absorption spectra of chlorophyll molecules in aqueous glycolipid and phospholipid dispersions are reported. The spectra show a shift for the red peak of chlorophyll of some 10 millimicrons to longer wavelength compared with the spectrum of chlorophyll in ether. Photochemical studies were carried out with cytochrome c incorporated into the aqueous layers separating the lipid bilayers.     

Bulk Carbohydrate Grain Filling of Barley β‐Glucan Mutants Studied by 1H HR MAS NMR

Temporal and genotypic differences in bulk carbohydrate accumulation in three barley genotypes differing in the content of mixed linkage β‐(1→3),(1→4)‐D‐glucan (β‐glucan) and starch were investigated using proton high‐resolution, magic angle spinning, nuclear magnetic resonance (¹H HR MAS NMR) during grain filling. For the first time, ¹H HR MAS NMR spectra of flour from immature barley seeds are analyzed. Spectral assignments are made using two‐dimensional (2D) NMR methods. Both α‐ and β‐glucan biosynthesis were characterized by inspection of the spectra as well as by calibration to the reference methods for starch and β‐glucan content. Starch was quantified with very good calibrations to the α‐(1→4) peak (5.29–5.40 ppm) and the region 3.67–3.83 ppm covering starch glycopyranosidic protons from H5 and H6. In contrast, the spectral inspection of the β‐anomeric region 4.45–4.85 ppm showed unexpected lack of intensity in the high β‐glucan mutant lys5f at seed maturity, resulting in poor calibration to reference β‐glucan content. We hypothesize that the lack of β‐glucan signal in lys5f indicates partial immobilization of the β‐glucan that appears to be either genotypic dependent or water/β‐glucan ratio dependent.     

Limited efficacy of West Nile virus vaccines in large falcons (Falco spp.)

West Nile virus (WNV) can lead to fatal diseases in raptor species. Unfortunately, there is no vaccine which has been designed specifically for use in breeding stocks of falcons. Therefore the immunogenicity and protective capacity of two commercially available WNV vaccines, both approved for use in horses, were evaluated in large falcons. One vaccine contained adjuvanted inactivated WNV lineage 1 immunogens, while the second represented a canarypox recombinant live virus vector vaccine. The efficacy of different vaccination regimes for these two vaccines was assessed serologically and by challenging the falcons with a WNV strain of homologous lineage 1. Our studies show that the recombinant vaccine conveys a slightly better protection than the inactivated vaccine, but moderate (recombinant vaccine) or weak (inactivated vaccine) side effects were observed at the injection sites. Using the recommended 2-dose regimen, both vaccines elicited only sub-optimal antibody responses and gave only partial protection following WNV challenge. Better results were obtained for both vaccines after a third dose, i.e. alleviation of clinical signs, absence of fatalities and reduction of virus shedding and viraemia. Therefore the consequences of WNV infections in falcons can be clearly alleviated by vaccination, especially if the amended triple administration scheme is used, although side effects at the vaccination site must be accepted.