NaCl和Na2CO3胁迫对桑树幼苗生长和光合特性的影响

以1年生“青龙桑”幼苗为试验材料,研究了中性盐(NaCl)和碱性盐(Na2CO3)胁迫下桑树幼苗的生长和叶片光合特性.结果表明： 盐胁迫明显降低了桑树幼苗的株高、叶片数、生物量和叶片的光合能力.随着Na+浓度的增加,桑树叶片的气孔导度、蒸腾速率、净光合速率、实际光化学效率、电子传递速率和光化学猝灭系数明显降低,过剩光能以非光化学猝灭形式耗散的比例增加,桑树叶片的光能转化效率和光合能力下降.在Na+浓度＜150 mmol·L-1时,桑树幼苗的光合能力和生长受到的抑制较小,通过增加根冠比进一步适应盐胁迫,但这种保护机制随着盐浓度的增加逐渐降低.在Na2CO3胁迫下,＞50 mmol·L-1Na+浓度对桑树的生长和光合能力表现出较强的抑制作用,并随Na+浓度的增加,抑制程度加大.在NaCl＜150 mmol·L-1时,桑树的光合能力主要依赖植株形态和光合代谢双重途径适应中性盐逆境,而在NaCl浓度＞150 mmol·L-1和碱性盐胁迫下,其主要依赖光合代谢来适应逆境.     

Cryptosporidium parvum: Radiation-induced alteration of the oocyst proteome

Cryptosporidium parvum is a waterborne protozoan parasite that is found intracellularly in host animals, including humans, and causes severe diarrhea, which can lead to the death of an immunocompromised individual. Previously, we found that this organism is highly radioresistant as it can productively infect mice after exposure to a 10-kGy dose of γ-radiation.To understand how C. parvum avoids radiation damage, we characterized its protein expression patterns 6, 24, and 48 h after a 10-kGy dose of γ-radiation using two-dimensional PAGE. The gels showed 10 silver-stained spots that increased or decreased in size following γ-irradiation. Five proteins contained in these spots were identified using MALDI-TOF MS peptide fingerprinting, and two of these showed an increase in expression after γ-irradiation. These proteins were identified by LC–MS/MS as proteasome subunit alpha type 4 (NTN hydrolase fold) and thioredoxin peroxidase-like protein. The roles of these two upregulated proteins as related to the radioresistance of C. parvum remain to be evaluated.     

牛源隐孢子虫分离株的分子鉴定

目的对安徽4个牛源隐孢子虫分离株进行鉴定,旨在阐明感染牛隐孢子虫主要虫种。方法采用PCR和Nested-PCR方法分别对4个分离株18S rRNA、HSP70基因进行扩增和测序,所测定的序列经生物信息学分析它们同源性和构建种系发育进化树,以确定各分离株与其他隐孢子虫虫种之间的亲缘关系。结果 （1）它们的18S rRNA基因和HSP70基因与安氏隐孢子虫（C.andersoni）AY954887相似性可达88.3%和98.3%;（2）在遗传进化树方面,它们与AY954892（河南株）亲缘关系接近。结论此次分离的4个牛源隐孢子虫分离株均为安氏隐孢子虫（Cryptosporidium andersoni）。     

The effects of time and temperature on flow cytometry enumerated live Cryptosporidium parvum oocysts

AIMS: Recoveries of spiked standard suspensions are used to evaluate method performance. For many applications, gamma-irradiated Cryptosporidium oocysts are appropriate. In contrast, methods that determine viability, such as Cryptosporidium cell culture, require the use of live oocysts. Oocyst standards are usually prepared at a flow cytometry laboratory for use at another laboratory, and thus the samples are shipped. The goal of this study was to evaluate the shipping and storage stability of flow cytometry enumerated live oocysts over time at three temperatures: 4 degrees C, room temperature and 37 degrees C. METHODS AND RESULTS: Replicate samples containing 100 live C. parvum oocysts were prepared by flow cytometry and stored at 4 degrees C, room temperature and 37 degrees C. These samples were counted at various time points. Significant oocyst losses were observed after storage for 1 day at 37 degrees C, 7 days at room temperature and 21 days at 4 degrees C. CONCLUSIONS: Live C. parvum oocysts internal standards should be used within 10 days of preparation, and stored and shipped at 4 degrees C. SIGNIFICANCE AND IMPACT OF THE STUDY: When evaluating method performance with live oocysts, both the storage temperature and time are critical factors for obtaining reliable and accurate results.     

Parasitophorous vacuole: morphofunctional diversity in different coccidian genera (a short insight into the problem)

We present a short insight into the problem of parasitophorous vacuole (PV) formation as a most peculiar kind of cell vacuolization occurring in the course of intracellular development of coccidian pathogens of the genera Eimeria, Isospora, Toxoplasma, Sarcocystis, Cryptosporidium, Epieimeria, and Karyolysus. The review focuses on the morpho-functional diversity of PVs in these parasites. By the present time, the PVs containing different parasite genera and species have been examined to different extent. The membrane of the PV (PVM) obviously derives from the host cell plasmalemma. But soon after parasite penetration, the morphofunctional organization and biochemical composition of the PVM drastically changes: its proteins are selectively excluded and those of the parasite are incorporated. As the result, the PV becomes not fusigenic for lysosomes or any other vacuoles or vesicles, because host cell surface markers necessary for membrane fusion are eliminated from the PVM during parasite invasion.The pattern of the PVs is parasite specific and demonstrates a broad diversity within the same genera and species and even at different stages of the endogenous development. The PV is far from being an indifferent membrane vesicle containing the parasite. Instead, it represents a dynamic system that reflects the innermost events of host-parasite relationships, thus promoting the accomplishing of the parasite life cycle, which, in its turn, is a necessary prerequisite of the parasite eventual survival as a species.     

松鼠分子生态学研究进展

松鼠由于受到非法猎捕、栖息地破坏及欧洲部分地区的北美灰松鼠生态入侵,导致种群数量锐减,现已被世界自然保护联盟(IUCN)列为近危种,我国吉林省已将其列入省重点保护野生动物名录.分子生物学研究方法的快速发展,尤其是基于mtDNA片段开展的相关研究,以及已筛选出并能应用于松鼠研究的微卫星位点的应用,使松鼠分子生态学研究不断深入.本文对松鼠的分子系统发育、遗传多样性和分子系统地理学等分子生态学内容进行了综述,并提出松鼠分子生态学未来研究的展望:进一步探讨松鼠与日本松鼠的系统分化关系;松鼠连续种群、隔离种群和集合种群的遗传多样性比较分析;利用核基因其他标记分析松鼠分子系统地理学问题;探讨亚洲是否存在第四纪冰期避难所.     

大兴安岭北部兴安落叶松林穿透雨延滞效应

以黑龙江漠河生态站兴安落叶松天然林为研究对象,对林外雨、穿透雨和树干茎流进行定位观测,分析大兴安岭北部兴安落叶松林穿透雨延滞效应.结果表明： 穿透雨量、树干茎流量和林冠截留量分别占同期降雨总量的76.5%、2.6%和20.9%.降雨发生后,穿透雨与林外雨在产生和终止时间上均存在一定延滞性;随降雨量级增大,穿透雨滞后时间表现出逐渐缩短的趋势,变动范围为（67.8±7.8）～（17.2±3.9） min（穿透雨）和（112.0±38.8）～（48.3±10.6） min（树干茎流）;相同降雨量级下,穿透雨滞后时间随降雨强度增大而逐渐降低,且降雨强度>2 mm·h^-1时延滞时间显著缩短,同时随雨前干燥期的增加而增长,而当雨前干燥期≥48 h时,降雨量则是影响滞后时间的主要因素;降雨终止时,降雨量>5.0 mm,穿透雨终止时间也存在延滞性,且随降雨强度增加而增大,但与雨前干燥期关系不明显;树干茎流终止时间先于林外雨终止时间,且主要与降雨量级有关,降雨量级越小,终止时间越早.     

银沙槐内生放线菌抗菌活性及其与内生细菌的拮抗关系

从荒漠濒危植物银沙槐根部分离到内生放线菌12株和内生细菌31株.以大肠杆菌、金黄色葡萄球菌和枯草芽孢杆菌为指示菌对内生放线菌进行了抗菌活性筛选.结果表明：3株放线菌对3种指示菌均有抑制作用,2株完全无抑菌作用.采用菌块抑制法分析内生放线菌对来自同一植物内生细菌的抑制效果,44.9%的组合出现抑制现象,最大抑菌圈直径为28.5mm,最小者仅8.25 mm,主要抑制对象是革兰氏阴性菌和芽孢菌;55.1%的组合无抑制现象.说明内生菌的相互作用具有多样性.     

猪IGF2基因外显子3的遗传多态性及遗传效应分析

采用PCR-SSCP方法检测猪胰岛素样生长因子2 (insulin-like growth factor 2,IGF2)基因外显子3多态性,分析其对初生重、断奶重、6月龄重和背膘厚的遗传效应.根据猪IGF2基因的DNA序列（AY044828）设计引物,结果在其扩增片段上检测到多态性,对纯合子进行测序,发现IGF2-ex3-A36T和IGF2-ex3-G109A两个多态性位点,并且这2个多态性位点完全连锁,检测到3种基因型（A36A/G109G,A36T/G109A 和 T36T/A109A）.统计结果表明,基因型在各品种中分布不一致,长白猪和大白猪与莱芜猪、大薄莲猪、沂蒙黑猪和里岔黑猪比较基因型分布差异极显著（Ｐ<0.01）;其它猪种间基因型分布差异均不显著（Ｐ>0.05）.固定效应模型分析结果表明,初生重和背膘厚基因型间差异显著（Ｐ<0.05）,而断奶重和6月龄重基因型间差异不显著（Ｐ>0.05）.最小二乘分析结果表明,A36A/G109G基因型个体同A36T/G109A和 T36T/A109A基因型个体比较初生重和背膘厚的差异显著（Ｐ<0.05）,3种基因型初生重的大小排列顺序为A36A/G109G < A36T/G109A < T36T/A109A,背膘厚的大小排列顺序为A36A/G109G > A36T/G109A >T36T/A109A.因此,推测IGF2基因对个体的初生重和胴体瘦肉率存在一定的影响,将IGF2基因应用于猪育种过程中的标记辅助选择,将可以改善猪肉品质,加快猪的育种进程.     

Verification of immunosuppression in chicks caused by Cryptosporidium baileyi infection using Brucella abortus strain 1119-3

Humoral immune response of young chicks to Brucella abortus strain 1119-3 inoculation was monitored to verify the degree of immunosuppression caused by infection with Cryptosporidium baileyi. Young chicks (2-day-old) were orally inoculated each with 2 × 10⁶ oocysts of C. baileyi, and then injected intramuscularly with 0.3 ml B. abortus strain 1119-3 containing 1 × 10⁹ living organisms on day 14 postinoculation (PI). Serum samples were tested by plate agglutination test on day 17 PI onwards at an interval of 3-6 days over a period of 36 days. Infected chicks with the coccidium showed significantly lower antibody titers than those of uninfected controls (P < 0.05). These findings document that C. baileyi infection in early life stage may predispose chicks easily to other potential poultry diseases.