Comparison of Worm Control Strategies in Grazing Sheep in Denmark

Control of nematode parasites with reduced reliance on the use of anthelmintics was studied in 16 ewes with suckling twin lambs on contaminated pasture in Denmark. Ewes and lambs were treated with albendazole at turn-out 3 May. Ewes were removed from the groups on 26 July, and lambs were slaughtered on 11 October. The animals were allocated to 4 groups of 8 lambs and their 4 ewes. Group TS was treated with albendazole at weeks 3, 6 and 8 after turnout and set-stocked; group TM was similarly treated but moved to clean pasture in conjunction with the last drenching; group US was untreated and set-stocked, and group UM was left untreated but moved to clean pasture week 8 after turn-out. Supplementary feed was offered in June and August due to scarcity of pasture. Strategic treatments of ewes and lambs weeks 3, 6 and 8 after turn-out, with or without a move to clean pasture, were highly effective in controlling nematode infections for most of the season. This was reflected in better weight gains and carcass characteristics in the treated compared to untreated lambs, resulting in an average increase in the value of the product by 36%. The effect of moving without treatment (UM) on faecal egg counts was limited but peak pasture infectivity was reduced to less than 10% compared to the set-stocked group and weight gains of lambs were significantly better despite poor feed availability in late season. The study showed that under set-stocked conditions repeated anthelmintic treatments of both ewes and lambs in early season may ensure sufficient nematode control whereas moving animals to clean pasture without dosing was less efficient. The latter may, however, still be a viable option in organic and other production systems where routine use of anthelmintics is banned, particularly if weaning and moving are combined or a second move is performed.     

Investigation of apoptosis in cultured cells infected with equine herpesvirus 1

Many viruses alter different stages of apoptosis of infected cells as a strategy for successful infection. Few studies have addressed mechanisms of equine herpesvirus 1 (EHV-1) strain-induced cell death. We investigated the effect of an abortigenic strain (AR8 strain) on heterologous Madin–Darby bovine kidney cells and homologous equine dermis (ED) cells cell lines. We compared morphologic and biochemical features of early and late apoptosis at different postinfection times. We investigated translocation of phosphatidylserine to the cell surface, nuclear fragmentation and changes in the cytoskeleton using flow cytometry and annexin V/propidium iodide staining, DNA laddering, terminal deoxynucleotidyl transferase UTP nick-end labeling assay and immunofluorescence staining of cytokeratin 18 cleavage. AR8 EVH-1 strain interfered with apoptosis in both cell lines, particularly during the middle stage of the replication cycle; this was more evident in ED cells. Although this antiapoptotic effect has been reported for other alpha herpesviruses, our findings may help elucidate how EHV-1 improves its infectivity during its cycle.     

在中国应用垂直波束雷达监测褐飞虱和其他水稻害虫迁飞的可行性

近年来,可用于昆虫迁飞研究且可自动运行的垂直波束雷达(vertical-looking radar,VLR)的发展使得对迁飞性害虫的周年长期自动监测成为可能。本文提供了我们对能否将这种雷达应用于中国的褐飞虱和其他水稻害虫的监测与预测体系以改善其综合治理的可行性研究结果。以往的研究已经表明,这些害虫一般在300—2000m高度迁飞;而我们根据褐飞虱的雷达和射有效截面的计算结果表明,目前使用的3．2cm波长的VLR对褐飞虱个体目标的最大可检测高度仅约240m;虽然建造一部8．8mm波长的VLR即可覆盖褐飞虱迁飞高度的绝大部分,但其造价和维护费用均过于昂贵。为此,一个更可行的解决方案是,以3．2cm波长的VLR作为包括大多数水稻害虫在内的个体较大的迁飞性害虫的监测工具。     

The Contributions of Sea Ice Algae to Antarctic Marine Primary Production

The seasonally ice-covered regions of the Southern Ocean havedistinctive ecological systems due to the growth of microalgaein sea ice. Although sea ice microalgal production is exceededby phytoplankton production on an annual basis in most offshoreregions of the Southern Ocean, blooms of sea ice algae differconsiderably from the phytoplankton in terms of timing and distribution.Thus sea ice algae provide food resources for higher trophiclevel organisms in seasons and regions where water column biologicalproduction is low or negligible. A flux of biogenic materialfrom sea ice to the water column and benthos follows ice melt,and some of the algal species are known to occur in ensuingphytoplankton blooms. A review of algal species in pack iceand offshore plankton showed that dominance is common for threespecies: Phaeocystis antarctica, Fragilariopsis cylindrus andFragilariopsis curta. The degree to which dominance by thesespecies is a product of successional processes in sea ice communitiescould be an important in determining their biogeochemical contributionto the Southern Ocean and their ability to seed blooms in marginalice zones.     

Functional changes in human leukemic cell line HL-60. A model for myeloid differentiation

Polar solvents induce terminal differentiation in the human promyelocytic leukemia cell line HL-60. The present studies describe the functional changes that accompany the morphologic progression from promyelocytes to bands and poly-morphonuclear leukocytes (PMN) over 9 d of culture in 1.3 percent dimethylsulfoxide (DMSO). As the HL-60 cells mature, the rate of O(2-) production increase 18-fold, with a progressive shortening of the lag time required for activation. Hexosemonophosphate shunt activity rises concomitantly. Ingestin of paraffin oil droplets opsonized with complement or Ig increases 10-fold over 9 d in DMSO. Latex ingestion per cell by each morphologic type does not change significantly, but total latex ingestion by groups of cells increases with the rise in the proportion of mature cells with greater ingestion capacities. Degranulation, as measured by release of β-glucuronidase, lysozyme, and peroxidase, reaches maximum after 3-6 d in DMSO, then declines. HL-60 cells contain no detectable lactoferrin, suggesting that their secondary granules are absent or defective. However, they kill staphylococci by day 6 in DMSO. Morphologically immature cells (days 1-3 in DMSO) are capable of O(2-) generation, hexosemonophosphate shunt activity, ingestion, degranulation, and bacterial killing. Maximal performance of each function by cells incubated in DMSO for longer periods of time is 50-100 percent that of normal PMN. DMSO- induced differentiation of HL-60 cells is a promising model for myeloid development.     

Isolation and characterization of subcellular protein fractions from mouse heart

In this study, we report different protocols used to obtain highly enriched and well-characterized protein fractions that could be used to determine the subcellular localization of proteins. Different protein fractions (total, cytosolic, total membrane, sarcolemmal, and nuclear) were isolated from mouse heart by a combination of either polytron homogenization or liquid nitrogen pulverization followed by density gradient centrifugation. Triton X-100 was used in specific fractions to help in the solubilization of proteins obtained with fractionation protocols. Following the isolation, enzymatic assays and Western blot analysis were used to evaluate the enrichment and/or cross-contamination of these protein fractions. Glucose-6-phosphate dehydrogenase, Na+/K+-ATPase, mitochondrial Ca2+-ATPase, sarco-endoplasmic reticulum Ca2+-ATPase, glucose-regulated protein, and nucleoporin P62 were used as specific markers for the cytosol, sarcolemma, mitochondria, sarco-endoplasmic reticulum, endoplasmic reticulum, and nucleus, respectively. The results show that we obtained enriched protein fractions with little to no cross-contamination. These purification protocols allow us to obtain different protein fractions that could be used in a wide variety of studies.     

RATES OF PHOTOADAPTATION IN SEA ICE DIATOMS FROM MCMURDO SOUND,ANTARCTICA1

Sea ice microalgae are released from their relatively stable light environment to the water column seasonally, and any subsequent growth in a vertically mixed water column may depend, in part, on their photoadaptation rates. In this study we followed the time course of photoadaptation in natural sea ice algal communities from bottom ice and surface ice by measuring their photophysiological response to an artificial shift in the ambient irradiance field. Microalgae from under-ice habitats, were incubated under full sunlight (LL-HL) and microalgae from surface ice habitats were incubated under artificial light to mimic under-ice irradiance (HL-LL). During 3- to 4-day time course studies, opposite shifts in chlorophyll: carbon, α, P^B_m, and I_k were observed, depending on the direction of the irradiance change. First-order rate constants (k) ranged from 0.0067 to 0.29 h^?1 for photosynthetic parameters, although P^B_m did not always show a clear change over time. Rates of photoadaptation for ice algae are comparable to k values reported for temperate phytoplankton, suggesting that sea ice algae may be equally capable of adapting to the light conditions experienced in a vertically mixed water column. This study presents the first evidence that sea ice microalgae are physiologically capable of adapting to a planktonic life and thus could serve as a seed population for polar marine phytoplankton blooms.     

Attention and the detectability of weak taste stimuli

Subjects detected weak solutions of sucrose or citric acid under conditions in which attention was directed toward one of the tastants or the other. Detection thresholds were measured using an adaptive, forced-choice procedure, with a three-down one-up rule, which computer simulations suggest should be more reliable than the popular two-down one-up rule. The thresholds were modestly but systematically lower for attended tastants than for unattended ones. Similar results have been reported in other sense modalities, including vision (greater sensitivity to stimuli presented to attended versus unattended spatial locations) and hearing (greater sensitivity to stimuli presented at attended versus unattended sound frequencies). Taken together, the findings are consistent with a general hypothesis regarding attention in sensory systems: gains or losses in detectability occur when a central attentional mechanism (or, conceivably, a preattentive mechanism) selectively and preferentially monitors signals arising from particular subsets of peripheral neural inputs.