Molecular characterization and pathogenicity of Francisella noatunensis subsp. orientalis isolated from cultured tilapia (Oreochromis sp.) in Taiwan

Francisella noatunensis subsp. orientalis is a causative agent of systemic granulomatous disease in tilapia. The present study was designed to understand the genetic and phenotypic diversities among Taiwanese Fno isolates obtained from tilapia (n = 17) and green Texas cichlid (Herichthys cyanoguttatus) (n = 1). The enzymatic profiles of the isolates were studied using the API ZYM system. Phylogenetic tree analysis of the 16S rRNA and housekeeping gene and pulsed‐field gel electrophoresis (PFGE) were carried out to determine the genotypic characters of all isolates. The phylogenetic tree showed similarity of 99%–100% nucleotide sequences of 16S rRNA and housekeeping genes compared to the Fno references genes from GenBank database. Comparatively, the results revealed an identical profile of enzymatic and PFGE pattern which was distincted from that of F. philomiragia. To understand the pathogenicity, the isolates were intraperitoneal injected to tilapia the gross lesions were observed concomitant with natural outbreak. Median lethal dose upon Nile tilapia and red tilapia were 9.06 × 10³ CFU/fish and 2.08 × 10² CFU/fish, respectively. Thus, our data provide understanding the epidemiology of Taiwanese Fno isolates, and help in development of future control and prevention.     

全株青贮构树对蛋鸡产蛋性能、蛋品质、器官指数及血清生化指标的影响

试验旨在研究全株青贮构树对海兰褐蛋鸡生产性能、蛋品质、器官指数及血清生化指标的影响.选取23周龄健康的海兰褐蛋鸡288只,随机分成3组,每组8个重复,每个重复12只鸡.对照组饲喂基础饲粮,试验组则分别在基础饲粮中添加1％和5％的青贮构树饲料,预试期7 d,正试期56 d.结果表明:与对照组相比,试验组提高了初产蛋鸡的平...     

稻茬小麦不同栽培模式产量差异形成的群体结构分析

为探究江苏稻茬小麦不同栽培模式下产量差异形成的原因,明确提高产量的调控途径,以小麦品种扬麦25为材料,分别在江苏省扬州市和兴化市两地种植,设置高密无氮(Y0,基本苗300×10~4株·hm~(-2),不施氮)、高密高氮(Y1,300×10~4株·hm~(-2),施氮300 kg·hm~(-2))、低密中高氮(Y2,150×10~4株·hm~(-2),施氮270 kg·hm~(-2))和中密中氮(Y3,225×10~4株·hm~(-2),施氮240 kg·hm~(-2))4种栽培模式,对不同栽培模式下小麦产量和群体结构的差异进行了分析。结果表明,扬州和兴化试验点产量均表现为Y3Y1Y2Y0,其中Y3与Y1及Y1与Y2模式的平均产量差值分别为434.54和312.82 kg·hm~(-2)。经通径分析,穗数差和粒重差是导致模式间产量差形成的主要原因。相关分析表明,乳熟期叶面积指数差、开花至乳熟期绿叶面积持续时间(LAD)差与产量差均呈显著正相关,花后干物质积累量差、孕穗至开花期绿叶面积持续时间差与产量差均呈极显著正相关。总体来看,基本苗225×10~4株·hm~(-2)、施氮量240 kg·hm~(-2)、基肥∶壮蘖肥∶拔节孕穗肥为5∶1∶4的栽培模式能够使稻茬小麦保持花后较高的叶面积指数和绿叶面积持续期,提高花后干物质积累量,是缩小产量差的主要调控途径。     

炼山后杉木幼林生长动态研究

本文通过连续四年定位研究,结果表明:炼山能明显地提高杉木造林成活率;对幼林生长有促进效应,但这种效应仅是短期的,一般在炼山后第一年至第三年;炼山还有利于一年生草本和阳性植物种类增加。     

山东花生花叶病毒的研究

 从表现生长抑制和花叶病状的花生叶分离到一种花生花叶病毒(PMV),可通过汁液和桃蚜(Myzus Persicae)传播,它的寄主范围包括豆科和非豆科植物,和花生斑驳病毒不同。病毒的体外存活力4-5天,致死温度40°-50℃,稀释终点10^-3-14^-4;用氯仿澄清,聚乙二醇沉淀和差速离心可部分提纯。病毒颗粒长约725毫微米,沉降系数173S。在感病的心叶烟(Nicotiana glutinosa)叶细胞质中可见典型的风轮状内含体,表明PMV是马铃薯Y病毒组的一个成员。     

橡胶树炭疽病流行规律研究

大田系统观察结果表明，橡胶树炭疽病发病过程有越冬，始发，流行和病情下降４个阶段，流行方式有暴发型和渐发型２种，流行曲线有多峰波浪型和单峰弓型，流行规律的研究结果表明，该病发生流行与菌量，物候，气候，品系，菌株和立地环境等有关，菌量和易感病组织是病害流行的基本条件，多雨高湿是病害流行的主导因素，不同地区的菌株致病性不同，在小区内相同条件下不同橡胶品系抗病性也不同。通过流行规律研究，提出该病的喷经防治     

Inhibitory effect and mechanisms of an anthocyanins- and anthocyanidins-rich extract from purple-shoot tea on colorectal carcinoma cell proliferation

One newly bred variety of tea cultivar, purple-shoot tea, was selected to evaluate its antiproliferative effects on colorectal carcinoma cells, as well as normal colon cells. The phytochemicals and identified catechins of purple-shoot tea extract (PTE) were significantly higher than that of ordinary tea, especially the anthocyanins (surpassed by 135-fold) and anthocyanidins (surpassed by 3.5-fold). PTE inhibited the proliferation of COLO 320DM (IC(50) = 64.9 μg/mL) and HT-29 (IC(50) = 55.2 μg/mL) by blocking cell cycle progression during the G(0)/G(1) phase and inducing apoptotic death. Western blotting indicated that PTE induced cell cycle arrest by reducing the expression of cyclin E and cyclin D1 in COLO 320DM and the upregulation of p21 and p27 cyclin-dependent kinase inhibitors in HT-29. Two cells treated with PTE also indicated the cleavage of PARP, activation of caspase 3, and an increased Bax/Bcl-2 ratio. Our results showed that PTE is a potential novel dietary agent for colorectal cancer chemoprevention.     

耕播方式与减氮对扬辐麦13氮素吸收利用的影响

为明确不同机械耕播方式下减氮对小麦氮素吸收利用的影响,在水稻秸秆全量还田条件下,以扬辐麦13为材料,研究两种机械耕播方式［板茬+2BMF-稻茬免耕条播机（NT）、旋耕+2BFG-10（8）230型播种机（CT）］和三个施氮模式［常规模式（N1）:施氮量270 kg·hm_-2,基肥∶分蘖肥∶拔节肥∶孕穗肥= 5∶1∶2∶2;减氮模式（N2）：施氮量225 kg·hm_-2,基肥∶分蘖肥∶拔节肥∶孕穗肥=5∶1∶2∶2;减氮减次模式（N3）：施氮量180 kg·hm_-2,基肥∶拔节肥=5∶5］对小麦氮代谢酶活性、氮素吸收利用特征以及籽粒产量的影响。结果表明,播种前土壤相对含水量为84%,与CT处理相比,NT处理提高了植株硝酸还原酶（NR）和谷氨酰胺合成酶（GS）活性,使花前氮素转运量增加和氮素在籽粒中的分配量分别增加10.78% (P<0.01)和7.56%（P<0.05）,获得较高的氮肥偏生产力和氮肥表观利用率,其最终籽粒产量提高5.36%（P<0.05）。N2处理在小麦生育中后期可维持较高的氮代谢酶活性,获得较高的氮肥利用效率,花后氮素积累量和籽粒产量与N1处理无显著差异;N3处理的氮肥利用效率最高,但氮代谢酶活性较低,影响氮素在植株中的积累和转运,且籽粒产量最低。因此,播前土壤偏湿条件下推荐采用NT耕播方式,配N2减氮模式,有利于小麦生育中后期维持较高的氮代谢酶活性和氮素的积累,促进氮素向籽粒转运,提升氮肥利用效率和籽粒产量,实现高产高效;若CT耕播方式下宜采用N1施肥方式才能实现稳产,但氮肥利用效率不高。