Depth gradients in food‐web processes linking habitats in large lakes: Lake Superior as an exemplar ecosystem

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Genome-wide association and genomic prediction for host response to porcine reproductive and respiratory syndrome virus infection

Background

Host genetics has been shown to play a role in porcine reproductive and respiratory syndrome (PRRS), which is the most economically important disease in the swine industry. A region on Sus scrofa chromosome (SSC) 4 has been previously reported to have a strong association with serum viremia and weight gain in pigs experimentally infected with the PRRS virus (PRRSV). The objective here was to identify haplotypes associated with the favorable phenotype, investigate additional genomic regions associated with host response to PRRSV, and to determine the predictive ability of genomic estimated breeding values (GEBV) based on the SSC4 region and based on the rest of the genome. Phenotypic data and 60 K SNP genotypes from eight trials of ~200 pigs from different commercial crosses were used to address these objectives.

Results

Across the eight trials, heritability estimates were 0.44 and 0.29 for viral load (VL, area under the curve of log-transformed serum viremia from 0 to 21 days post infection) and weight gain to 42 days post infection (WG), respectively. Genomic regions associated with VL were identified on chromosomes 4, X, and 1. Genomic regions associated with WG were identified on chromosomes 4, 5, and 7. Apart from the SSC4 region, the regions associated with these two traits each explained less than 3% of the genetic variance. Due to the strong linkage disequilibrium in the SSC4 region, only 19 unique haplotypes were identified across all populations, of which four were associated with the favorable phenotype. Through cross-validation, accuracies of EBV based on the SSC4 region were high (0.55), while the rest of the genome had little predictive ability across populations (0.09).

Conclusions

Traits associated with response to PRRSV infection in growing pigs are largely controlled by genomic regions with relatively small effects, with the exception of SSC4. Accuracies of EBV based on the SSC4 region were high compared to the rest of the genome. These results show that selection for the SSC4 region could potentially reduce the effects of PRRS in growing pigs, ultimately reducing the economic impact of this disease.     

Acetylcholine and cholecystokinin induce different patterns of oscillating calcium signals in pancreatic acinar cells

Receptor-activated cytoplasmic calcium (Ca2+) oscillations have been investigated in single pancreatic acinar cells by microfluorimetry (Fura-2 as indicator). At submaximal concentrations of the agonists acetylcholine (ACh) and cholecystokinin octapeptide (CCK-8), both give rise to oscillatory changes in the cytosolic free calcium concentration ([Ca2+]i). The patterns of oscillations are markedly and consistently different for each of these two agonists. The ACh induced oscillations are superimposed upon a median elevation in background [Ca2+]i. The CCK-8 induced oscillations are of longer duration with [Ca2+]i returning to prestimulus levels between the discrete spikes. The ACh induced oscillations are rapidly abolished upon removal of extracellular Ca2+ while the CCK-8 induced oscillations persist for many minutes in the absence of external Ca2+. The CCK-8, but not the ACh, induced oscillations are increased in duration by the protein kinase C (PKC) inhibitor staurosporine and abolished by the PKC activating phorbol ester PMA. It is clear that CCK-8 and ACh do not activate receptor transduction mechanisms in an identical manner to generate oscillating [Ca2+]i signals.     

Stimulant-evoked depolarization and increase in [Ca2+] i in insulin-secreting cells is dependent on external Na+

Summary The patch-clamp technique and measurements of single cell [Ca²⁺] _i have been used to investigate the importance of extracellular Na⁺ for carbohydrate-induced stimulation of RINm5F insulin-secreting cells. Using patch-clamp whole-cell (current-clamp) recordings the average cellular transmembrane potential was estimated to be –60±1 mV (n=83) and the average basal [Ca²⁺] _i 102±6nm (n=37). When challenged with either glucose (2.5–10mm) ord-glyceraldehyde (10mm) the cells depolarized, which led to the initiation of Ca²⁺ spike potentials and a sharp rise in [Ca²⁺] _i . Similar effects were also observed with the sulphonylurea compound tolbutamide (0.01–0.1mm). Both the generation of the spike potentials and the increase in [Ca²⁺] _i were abolished when Ca²⁺ was removed from the bathing media. When all external Na⁺ was replaced with N-methyl-d-glucamine, in the continued presence of either glucose,d-glyceraldehyde or tolbutamide, a membrane repolarization resulted, which terminated Ca²⁺ spike potentials and attenuated the rise in [Ca²⁺] _i . Tetrodotoxin (TTX) (1–2 m) was also found to both repolarize the membrane and abolish secretagogue-induced rises in [Ca²⁺] _i .     

The dynamics of recalcitrant seed banks of <Emphasis Type="Italic">Mauritia flexuosa</Emphasis> (Arecaceae) reveal adaptations to marsh microenvironments

The Mauritia flexuosa palm tree is widely distributed in South America, and is associated with flooded environments. It dominates the arboreal stratum in the highly threatened marsh ecosystems called “veredas” in the Cerrado biome (neotropical savanna), and its oleaginous fruits are important for the maintenance of the regional fauna and as a source of income for traditional human populations. The seeds of this palm demonstrate an unusual association of recalcitrance and dormancy, and information about its seed bank maintenance in natural environments is scarce. We measured the variations in water content, viability, and germination of seeds maintained over 1 year in four typical vereda microenvironments (edge, near the water, in the water, and at the lower zone of the vereda) and related that information to soil water contents and climatic data. Seed viability was best preserved under constantly flooded conditions (at the lower zone of the vereda), with the potential for maintaining a temporary seed bank in the aquatic environment that would favor dispersal. Although the seeds are intolerant of dehydration, they have a high capacity for maintaining their water contents under partially drained soil conditions, and overcoming dormancy is favored under those conditions. Mauritia flexuosa establishment strategies are driven by sophisticated interactions with climate and with vereda microenvironments, with a tendency for maintaining seed banks and seedling banks in localities with flooded or drained soils, respectively.     

Neurotoxic,cytotoxic, apoptotic and antiproliferative effects of some marine algae extracts on the NA2B cell line

Oxidative stress contributes to cancer pathologies and to apoptosis. Marine algae exhibit cytotoxic, antiproliferative and apoptotic effects; their metabolites have been used to treat many types of cancer. We investigated in culture extracts of Petalonia fascia, Jania longifurca and Halimeda tuna to determine their effects on mouse neuroblastoma cell line, NA2B. NA2B cells were treated with algae extracts, and the survival and proliferation of NA2B cells were assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The effects of algae extracts on oxidative stress in NA2B cells also were investigated using nitric oxide synthase (NOS) immunocytochemistry and apoptosis was assessed using terminal deoxynucleotidyl transferase dUTP nick end labeling. We observed significant neurite inhibition with moderate damage by the neurotoxicity-screening test (NST) at IC₅₀ dilutions of the extracts. MTT demonstrated that J. longifurca extracts were more toxic than P. fascia and H. tuna extracts. We found an increase of endothelial and inducible NOS immunostaining for oxidative stress and TUNEL analysis revealed increased apoptosis after application of extract. Our findings suggest that the algae we tested may have potential use for treatment of cancer.     

烟叶脉坏死病毒原鉴定及cDNA克隆与序列分析

田间采集辽宁地区烟叶脉坏死病标样所得分离物,在测定的１２个科３５种植物中只侵染茄科的一些烟草品种及洋酸浆（ｐｈｙｓａｌｉｓｆｌｏｒｉｄａｎａ）,可由桃蚜（Ｍｙｚｕｓｐｅｒｓｉｃａｅ）传播。病叶汁液稀释限点（ＤＥＰ）为１０￣（－２）－v１０￣（－３）;失毒温度（ＴＩＰ）为５５一６０℃;体外保毒期（Ｌ）为４８－７２小时。病毒粒体形态呈线条状７２０×１２ｎｍ,病叶脉坏死部细胞质中含风轮状内含体。病毒提取物的紫外最大吸收为２６５ｎｍ,最小吸收为２４５ｎｍ,Ａ＿（２８０）／Ａ＿（２６０）为０．８２。该病毒分离物与ＰＶＹ￣０抗血清呈阳性反应。以病毒ＲＮＡ为模板,按国外报道的ＰＶＹ￣Ｎ序列合成引物经逆转录合成ｃＤＮＡ。用ＰＣＲ扩增出约０．８０ｋｂ的ＣＰ基因片段,将这一片段插入载体ｐＧＥＭ７Ｚ－ｆ（＋）中转化Ｅ．ｃｏｌｉＤＨ５ａ菌株得到了ＣＰ基因的克隆。ｃＤＮＡ序列分析表明,和国外报道的ＰＶＹ￣Ｎ序列同源性极高,初步表明引起辽宁地区烟叶脉坏死病的毒原为ＰＶＹ￣Ｎ。     

Aspects of the reproductive biology ofPollicipes pollicipes (Cirripedia; Lepadomorpha) from the southwest coast of Portugal

The pedunculated cirripedePollicipes pollicipes is of considerable economic importance in Portugal, particularly along the southwest coast. Current knowledge of its biology is poor, as evidenced by the paucity of available literature. This paper reports on the reproduction of twoP. pollicipes populations, Castelejo and Zavial, on the southwest coast of the Algarve. Differences in reproductive patterns between the two sites were minor and not statistically significant, despite differences in environmental conditions between the two sites. Adult animals carried fertilised eggs from April throughout September, and the percentage of individuals with egg masses correlated positively with air but not with sea water temperature. Brooding success was greater with average air temperature in excess of 14°C during months of strong upwelling and presumed food availability. Functional ovaries and testes are available in the population all year round but fertilisation does not appear to occur during the winter months. Reproduction ofP. pollicipes on the southwest coast of the Algarve appears closely linked to the upwelling phenomenon with the rate of deposition of gonadal tissue probably being determined by environmental temperature. The cues which determine the cessation of fertilisation remain to be investigated.