Forest-edge utilization by carnivores in relation to local and landscape habitat characteristics in central European farmland

Rapid changes in agricultural landscape structure and composition affect many different farmland biotas, including carnivores, which are a key element of ecosystem stability, yet little is known about their distribution and habitat use. In this study, we evaluated how habitat characteristics on two different spatial scales (local and landscape scale) affected the forest-edge utilization by small and medium-sized carnivores in fragmented central European farmland. Based on an indirect method for detecting carnivores (scent stations), we sampled 212 forest fragments of different sizes (1–7864 ha) during April to May from 2006 to 2009. Our results indicate that carnivore utilization of forest-edge habitats was driven by landscape rather than local characteristics even though the overall extent of explained variation was small. The most important factors that determined response of the carnivore community were the area of farmland and that of urban land on a landscape scale. The corridor connectivity between small forest fragments and other spatial elements played a crucial role in the occurrence of red fox. Our results suggest that comprehensive studies on multi-species carnivore assemblage using scent station might be useful in evaluating species-specific response to habitat characteristics, especially if large numbers of stations visited by carnivores are available.     

tRNA-dependent amide bond–forming enzymes in peptide natural product biosynthesis

In the ribosome-independent biosynthesis of peptide natural products, amino acid building blocks are generally activated in the form of phosphoesters, esters, or thioesters prior to amide bond formation. Following the recent discovery of bacterial enzymes that utilize an aminoacyl ester with a transfer ribonucleic acid (tRNA) in primary metabolism, the number of tRNA-dependent enzymes used in biosynthetic studies of peptide natural products has increased steadily. In this review, we summarize the rapidly growing knowledge base regarding two types of tRNA-dependent enzymes, which are structurally and functionally distinct. Initially, we focus on enzymes with the GCN5-related N-acetyltransferase fold and discuss the catalytic function and aminoacyl-tRNA recognition. Next, newly found peptide-amino acyl tRNA ligases and their ATP-dependent reactions are highlighted.     

白腐真菌血红密孔菌漆酶复合酶预处理烟梗丝的响应面法优化

烟梗是烟草工业的重要副产物,也是宝贵的自然资源。本研究首先利用白腐菌漆酶对烟梗丝进行预处理,提升了添加烟梗丝的卷烟品质;然后分别以木质素、纤维素、半纤维素和果胶的降解率为响应值,采用Box-Behnken设计建立方程模型,对漆酶、纤维素酶、半纤维素酶和果胶酶组成的复合酶预处理烟梗丝条件进行了优化。结果表明：每100g烟梗丝加入30U漆酶,在料液比为35%、温度为30℃、酶解pH为5处理48h的条件下预处理的烟梗丝对提升卷烟品吸效果最佳,烟梗丝中木质素、纤维素、半纤维素和果胶的降解率分别为20.16%、15.10%、7.20%和12.40%;为获得与之相同的各组分降解率,响应面法优化漆酶复合酶最佳处理条件为：每100g烟梗丝加入漆酶14.72U、纤维素酶1.00U、半纤维素酶1.00U、果胶酶8.45U。验证发现烟梗丝各组分降解率实测值与理论值无显著性差异,且显微结构观察显示复合酶处理后的烟梗丝表面致密结构被破坏,孔洞数量明显增加。本研究获得的白腐菌漆酶预处理后的烟梗丝在卷烟中的添加能有效改善卷烟品质,且漆酶复合酶的使用大幅减少了漆酶的用量,降低了漆酶预处理烟梗丝的成本,为废弃烟梗生物质的资源化利用提供了重要依据。     

低剂量与常规剂量扫描在CT引导下经皮穿刺肺活检术中的临床应用价值对比研究

摘要 目的：比较低剂量与常规剂量扫描在CT引导下经皮穿刺肺活检术中的临床应用价值。方法：选择2018年1月至2019年12月我院行CT引导下经皮穿刺肺活检术的患者96例,采用随机数字表法分为低剂量组和常规剂量组,每组48例,两组分别在低剂量扫描、常规剂扫描下行CT引导下经皮穿刺肺活检术,比较两组扫描范围、X射线剂量、图像质量、穿刺成功率及并发症发生情况。结果：低剂量组CT吸收剂量加权指数（CTDIw）、平均剂量长度乘积（DLP）显著低于常规剂量组（P<0.05）,两组扫描范围比较无统计学差异（P>0.05）。低剂量组图像质量1级1例、2级1例、3级46例;常规剂量组1级0例、2级1例、3级47例,两组图像质量比较无统计学差异（P>0.05）。低剂量组穿刺成功率87.50%,常规剂量组穿刺成功率89.58%,两组穿刺成功率比较无统计学差异（P>0.05）。低剂量组并发症发生率为12.50%,常规剂量组并发症发生率为10.42%,两组并发症发生率比较差异无统计学意义（P>0.05）。结论：与常规剂量扫描相比,在CT引导下经皮穿刺肺活检术中应用低剂量扫描可以有效降低辐射剂量,但不影响图像质量和穿刺成功率,患者并发症发生率也未增加,具有较好的临床价值。     

不同含水率饲料对黑水虻生长发育的影响及其对饲料的转化特征研究

饲料的含水率是影响黑水虻生长发育及其对饲料养分转化的重要因素,本研究旨在探究黑水虻生物转化过程中饲料最佳含水率。将3龄黑水虻幼虫接入含水率为40%、50%、60%、70%、80%的饲料中,每隔3 d记录黑水虻的体重,至预蛹数达总数的50%时结束试验,计算预蛹历期、预蛹总产量及有效转化率,测定黑水虻及饲料残渣养分及总能。结果发现：1）黑水虻预蛹总产量及其对饲料的有效转化率随水分含量升高而线性增加,在80%水分下达到最大值。2）黑水虻在70%水分下最先预蛹,预蛹历期为14 d。3）黑水虻体内CP含量随水分含量增加而线性下降,EE、GE含量随水分增加线性上升。4）黑水虻对饲料GE的代谢消耗率在60%水分下最高,而在80%水分下对饲料养分的累积量最高。因此,生产中为了高效运转黑水虻生物转化体系,应根据生产目的调节饲料水分以获取最大效益。     

Dietary supplementation of plant bioactive-enriched aniseed straw and eucalyptus leaves modulates tissue fatty acid profile and nuggets quality of lambs

Utilization of low-input feed resources rich in plant bioactive compounds is a promising strategy for modulating the fatty acid profile in ruminant products. They manipulate microbes involved in rumen biohydrogenation and increase the accumulation of desirable fatty acids at the tissue level. Therefore, the present study was undertaken to assess the effect of dietary supplementation of aniseed straw and eucalyptus leaves on growth performance, carcass traits and fatty acid profile of finisher lambs. Thirty-six Malpura hogget were divided into three treatment groups of 12 each, reared individually in pen (1.6 m × 1.1 m) and fed ad libitum complete feed blocks made up of 55 parts concentrate, 5 parts molasses and 40 parts roughage. Roughage in control (Con) was 20 parts each of ardu (Ailanthus excelsa) leaves and oat (Avena sativa) straw. In test diets, that is, Con-as and Con-el, 10% aniseed (Pimpinella anisum) straw and Eucalyptus rudis leaves, respectively, were added by replacing 5% each of oat straw and eucalyptus leaves. The lambs were weighed weekly; and at the end of 3 months of feeding trial, the lambs were slaughtered to study the carcass traits, composition and product evaluation. Average daily gain (ADG) and DM intake (DMI) was higher (P < 0.05) in Con-as compared to Con and Con-el, while ADG and feed conversion ratio decreased (P < 0.05) by 29.4% and 36.4%, respectively, in Con-el compared to Con. Carcass traits showed lower (P < 0.05) loin eye area and chilling loss in the Con-el group compared to the Con-as and Con, and the total carcass fat compared to Con-as. However, the keeping quality of meat improved in both Con-as and Con-el which was reflected by lower (P < 0.05) thiobarbituric acid-reactive substances values. Nuggets prepared from Con and Con-as meat had superior (P < 0.05) sensory attributes with an overall palatability. Fatty acid profile of longissimus thoracis muscle showed lower (P < 0.05) atherogenic and thrombogenic indices in Con-as and higher (P < 0.05) in Con-el group. Moreover, in Con-as group, the proportion of C16:0 was lower (P < 0.05) and C18:3n-3 was higher (P < 0.05), but no effect was observed on the amount of conjugated linoleic acid (CLA; C18:2 c9t11). In case of adipose tissue, the content of CLA was higher (P < 0.05), and the ratio of n-6:n-3 was more nearer to desirable levels in Con-as group. Therefore, it can be concluded that aniseed straw is a promising feed supplement compared to eucalyptus leaves for improving meat quality and fatty acid profile in lambs.