Physicochemical properties of the thermal gel of water-washed meat in the presence of the more soluble fraction of porcine sarcoplasmic protein

We investigated the physicochemical properties of the thermal gel of water‐washed pork meat (WWM) in the presence of the soluble fraction of porcine sarcoplasmic protein (SP) obtained with ammonium sulfate at 75 percent saturation. Two precipitated fractions of SP were obtained at 0–50 percent and 50–75 percent saturation, named SP‐f1 and SP‐f2, respectively, and the soluble fraction obtained at 75 percent saturation, SP‐f3, was used. Sodium dodecyl sulfate‐polyacrylamide gel electrophoresis showed that SP‐f3 contained mainly glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH), while SP‐f1 and SP‐f2 had other SPs such as phosphorylase b, enolase, actin and phosphoglycerate mutase. The gel strength of WWM was greater when SP‐f3 rather than one of various animal proteins such as bovine plasma (BP), egg white, or whey protein isolates (WPI), was added and SP‐f3 had a gel‐enhancing effect as good as that of polyphosphate (PP). The gel strength of WWM with added SP‐f3 increased significantly with NaCl at 0.15 mol/L or more, but not in the absence of NaCl (0 mol/L). The effect of SP‐f3 was evident at neutral pH and maximum gel strength was obtained at a pH above 6.0. Differential scanning calorimetric (DSC) analysis showed that an endothermic peak corresponding to myosin heads in WWM shifted to a lower temperature with the addition of SP‐f3, as in the case of PP, though there was no such shift in the presence of other animal proteins (BP, egg white and WPI), suggesting that SP‐f3 increases the gel strength of WWM through the dissociation of actomyosin similar to PP. Scanning electron microscopy (SEM) revealed wall‐like structures among the protein strands in the WWM gel matrix in the presence of SP‐f3. The results of DSC and SEM indicated that the formation of a gel network in meat products is reinforced with GAPDH in SP after the interaction between GAPDH and myofibrillar protein.     

Validation and application of real-time polymerase chain reaction assays for representative rumen bacteria

Real‐time polymerase chain reaction (PCR) assays for 11 representative rumen bacterial species were validated. The sensitivity was tested by using the serially diluted target 16S rDNA from respective bacterial species. The recovery of the target DNA and the assay reproducibility were determined using DNA from rumen fluid spiked with different quantities of the target. Minimum detection levels for the target were 10–100 copies in pure culture. The recovery of the added target ranged from 82.4 to 116.6%. The intra‐ and inter‐assay variations of each assay were <9.4 and <12.6%, respectively. Therefore, the real‐time PCR assays evaluated in the present study are considered to be sufficiently reliable for monitoring all 11 bacterial species in the rumen. The assays were then applied to the monitoring of the bacterial species attached to ruminally incubated rice straw. Among the monitored fibrolytic species, Fibrobacter succinogenes was found to be the most dominant, accounting for 2.61% of total bacteria after 24 h incubation. Selenomonas ruminantium and Streptococcus bovis, non‐fibrolytics, were detected on the rice straw at 8.96% and 1.16% of total bacteria, respectively. Such high levels of non‐fibrolytics on the plant fiber suggest a synergistic relationship between fibrolytics and non‐fibrolytics.     

Identification of polymorphisms and association analysis with meat quality traits in the porcine KIAA1717 and HUMMLC2B genes

Skeletal muscle genes are potential candidates for production and meat quality. Screening a subtracted cDNA library constructed with mRNA obtained from longissimus dorsi muscles of F1 hybrids Landrace × Yorkshire and their female parents Yorkshire, we isolated two partial sequences coding for the H3-K4-specific methyltransferase (KIAA1717) and skeletal muscle myosin regulatory light chain (HUMMLC2B) genes. Database search revealed KIAA1717 and HUMMLC2B encoded proteins with SET domain and EF-hand calcium binding motif, respectively. In the present work we identified their partial polymorphisms and two SNPs, one (C1354T) at the 3′ untranslated region (UTR) of KIAA1717 and one (A345G) at the SINE (PRE-1) element of HUMMLC2B, both created/disrupted a restriction site for endonuclease Msp I. The selected pigs were genotyped at the KIAA1717 C1354T and HUMMLC2B A345G sites by means of a PCR-RFLP protocol. Significant associations were observed for the KIAA1717 C1354T polymorphic site with meat marbling (longissimus doris (p < 0.05), biceps femoris (p < 0.01)) and intramuscular fat (p < 0.01). HUMMLC2B A345G were significantly associated with meat pH (longissimus doris (p < 0.05), biceps femoris (p < 0.01)), drip loss (p < 0.01), water holding capacity (p < 0.01) and meat color value (longissimus doris (p < 0.01), biceps femoris (p < 0.05)). Further studies are needed to confirm these preliminary results.     

16S rRNA基因及外膜蛋白基因分析在鸭疫里默氏菌鉴定中的应用

本实验对鸭疫里默氏菌（包括6个血清型）、大肠杆菌、鼠伤寒沙门氏菌和多杀性巴氏杆菌进行了16S rRNA基因片段的扩增和测序，并将测序结果进行了同源性比较和酶切分析；同时根据标准血清2型鸭疫里默氏菌外膜蛋白的基因序列设计一对引物进行扩增。根据16S rRNA的测序结果及EcoRⅠ和HaeⅢ酶切片段分析，可将鸭疫里默氏菌与其它临床症状易混淆的细菌感染相区别，而外膜蛋白基因序列的特异性也为鸭疫里默氏菌的鉴别诊断提供了一种快速、准确的PCR鉴定方法。     

灭虫精对西施舌幼贝的毒性试验

在静水条件下,进行灭虫精对西施舌幼贝的毒性试验,试验结果显示:灭虫精对西施舌幼贝24 h致死浓度LC100为400 ms／L,半数致死浓度LC100为250 mg/L,安全浓度为2．50mg／L;48h致死浓度为260 mg／L,半数致死浓度LC50为224ms／L,安全浓度为2．24mg／L。灭虫精用于西施舌人工育苗过程中桡足类等敌害生物防治,具有较强的可用性。根据试验结果,建议使用2 mg／L浓度的灭虫精进行防治,可达到显著效果。     

Interactions between dietary fatty acids and hepatic gene expression in livers of pigs during the weaning period

The aim of the present study was to evaluate the impact of dietary fatty acids (FA) during the weaning period on expression of genes involved in the oxidation and metabolism of FA (peroxisome proliferator-activated receptor (PPAR-), stearoyl-CoA-desaturase (SCD), Δ6-desaturase (D6D), acetyl CoA carboxylase (ACC) and fatty acid synthase (FAS)). Liver samples were obtained from littermates, either on day 28 of age just before weaning, or at day 56 after the 4 weeks ad lib. provision of 5% of either animal fat, fish oil or sunflower oil. In conclusion, genes involved in the regulation of FA conversion (SCD, D6D) were influenced by the n-6 to n-3 ratio, whereas the FA oxidation, as indicated by the expression of PPAR-, was highly likely regulated by the hepatic ratio between mono- and poly-unsaturated FA. Furthermore, weaning and/or age affected the hepatic expression of genes involved in FA synthesis and conversion, but not the expression of PPAR-.     

Genetic, phenotypic and pathogenic diversity among xanthomonads isolated from pistachio (Pistacia vera) in Australia

Repetitive extragenic palindromic polymerase chain reaction (rep-PCR), sequencing of the 16S−23S rDNA internal transcribed spacer (ITS), biochemical and physiological tests, the Biolog microplate system, polyacrylamide gel electrophoresis (PAGE) of whole-cell proteins, and pathogenicity tests were used to characterize variability among xanthomonads isolated from pistachio trees suffering from bacterial dieback in four regions of Australia. ITS sequencing and rep-PCR revealed two distinct genotypes among the strains. The ITS sequencing suggested that the pistachio strains were closely related to Xanthomonas translucens pathovars, in particular X. translucens pv . poae . Results of physiological and biochemical tests, as well as Biolog microplate analysis and protein profiling, confirmed the existence of two groups. Furthermore, pathogenicity and host-range studies indicated that the two groups were biologically different. There was an association between the two groups and the geographical origin of the strains.     

A target-site mutation is present in a glyphosate-resistant Lolium rigidum population

Annual ryegrass (Lolium rigidum) is the only weed species to have evolved resistance to the broad‐spectrum herbicide glyphosate in Australia. A population that had failed to be controlled by glyphosate was collected from a vineyard in the Adelaide Hills region of South Australia. Dose–response experiments on this population (SLR 77) showed that it was glyphosate resistant, with an LD₅₀ that was 1.9–3.4 times higher than that of a susceptible population (VLR 1). The movement of radiolabelled glyphosate within SLR 77 plants showed that this population did not have the differential glyphosate translocation mechanism of resistance common to several other Australian glyphosate‐resistant populations. Subsequent analysis of shikimic acid accumulation within the plant after glyphosate treatment showed that this population accumulated significantly less shikimic acid than a susceptible population, but more than a glyphosate‐resistant population with the translocation mechanism, indicating the possible involvement of another mechanism of resistance. Sequencing of a portion of the SLR 77 5‐enolpyruvylshikimate‐3‐phosphate synthase gene was carried out and a mutation causing an amino acid change at position 106 from proline to threonine was identified. This mutation is likely to be responsible for glyphosate resistance in this population, as mutations in this position have been found to be responsible for glyphosate resistance in goosegrass (Eleusine indica) from Malaysia. This paper represents the first report of target‐site glyphosate resistance in L. rigidum and provides evidence that this species has at least two mechanisms of glyphosate resistance present in Australia.     

Biological activity and characterization of nucleopolyhedrovirus isolates ofSpodoptera litura

Geographical isolates ofSpodoptera litura (Fabricius) (Noctuidae: Lepidoptera) nucleopolyhedrovirus (SpltNPV), collected from different parts of India and maintained at Tamil Nadu Agricultural University, were compared for their biological activity and subjected to Restriction Endonuclease (REN) analysis. Neonate and second instar bioassay studies revealed similarity in biological activity as shown by the overlapping fiducial limits of LC₅₀ values. However, there were differences in yield among isolates: significantly higher yields were obtained from isolates UAS and CBE than from the BARC isolate. REN analysis of the four isolates withPst I,Hind III,Bam HI andEco RI enzymes indicated genotypic variation among the isolates. Based on the commonality of the bands, the isolates could be broadly divided into two groups: isolates AU and CBE formed one group, and the other group comprised UAS and BARC based on genetic relatedness. http://www.phytoparasitica.org posting Nov. 21, 2005.     

Prevention of progeny formation in Drosophila melanogaster by 1-arylimidazole-2(3H)-thiones

Effects of 1-arylimidazole-2(3H)-thiones (AITs) and 1-(substituted benzyl)imidazole-2(3H)-thiones (BITs) were tested on progeny formation in Drosophila melanogaster. Some AITs showed inhibitory activities at laying eggs and delayed eclosion by 1 day. The inhibitory activity was nullified by adding octopamine (OA) or noradrenaline (NA) to the medium for progeny formation in D. melanogaster. The effect of AIT on the contents of OA and NA was analyzed in adults of D. melanogaster by high-performance liquid chromatography with electrochemical detection. Flies fed with AIT decreased OA and NA levels and increased TA content. Taken together, the inhibitory activity of AIT could be due to inhibition of tyramine β-hydroxylase and dopamine β-hydroxylase.