短管兔耳草多糖的结构表征及其免疫调节活性研究

本试验旨在从短管兔耳草（Lagotis brevituba Maxim）中分离纯化多糖,初步分析多糖的结构表征并研究其体外免疫调节活性。采用水提醇沉法从短管兔耳草中提取粗多糖,经DEAE-52纤维素离子交换柱进行分离纯化,得到短管兔耳草多糖（Lagotis brevituba Maxim polysaccharide,LMP）。采用高效凝胶色谱法（HPGPC）、傅里叶变换-红外光谱法（FT-IR）、紫外光谱法（UV）等方法对其结构进行初步分析,并以小鼠骨髓来源树突状细胞（murine bone marrow derived dendritic cells,BMDCs）为靶细胞,采用MTT法、流式细胞术（FCM）、酶联免疫吸附试验（ELISA）等对其免疫活性进行测定。结果显示：从短管兔耳草中分离到不含核酸和蛋白质的多糖LMP,得率为（18.5±1.7）%,糖含量为（89.7±1.9）%,平均分子量为3.18 ku,平均粒径为1 483.89 nm,Zeta电位为-14.81 mV。扫描电镜（SEM）和原子力显微镜（AFM）结果显示,LMP的表面光滑,呈片状分布,单链的高度在5.4 nm左右。3.13～50.00 μg·mL^-1 LMP能显著促进BMDCs增殖（P<0.05）及其表面分子（CD80、CD86、MHC-Ⅰ和MHC-Ⅱ）的表达（P<0.05）和细胞因子（TNF-α、IL-12）的分泌（P<0.05）,同时显著降低BMDCs的吞噬能力（P<0.05）。LMP能促进BMDCs表型和功能的成熟,具有较好的免疫调节活性,可将其作为潜在的免疫调节剂。     

First spike latency of ON/OFF neurons in the optic tectum of pigeons

Some shallow and middle optic tectum (OT) neurons have stable, asymmetric full‐screen ON and OFF stimulus response properties, which makes them candidates for delay encoding. In this paper, we investigated the delay encoding mechanism for the neuronal clusters in the OT region of pigeons and determined the mechanism of delay coding in the OT region. By analyzing the responses of the neuron cluster under full‐screen switch‐on and switch‐off stimulation, we found that the delay coding was widespread in the OT region where the ON/OFF stimulation time difference was 4–6 ms. Information theory analysis under grating stimulation and experiments based on single‐neuron character reconstruction of neurons showed that OT neuron clusters use the first spike latency (FSL) for the rapid transfer of spatial structure information. Furthermore, 4 models were used to predict the first spike latency of these OT neurons. The best simulation results were obtained using an architecture where the ON and OFF paths of multiple retinal ganglion cells (RGCs) were integrated and summed, respectively.     

贫困地区少数民族女性弹性就业可持续生计评价研究

推进贫困地区女性就业脱贫对增强女性自我发展能力,促进家庭可持续发展具有重要意义.本文借鉴参与式农村评价法、可持续生计框架理论,对新疆喀什地区2020年脱贫县典型乡镇进行实地抽样调查,从个人禀赋、家庭特征与社会保障层面对少数民族女性脆弱性贫困进行分类识别,建立少数民族女性弹性就业可持续生计资产评价体系,测算其家庭生计资产...     

内生细菌对NaCl胁迫下小麦幼苗的缓解作用

选择小麦种子作为研究材料,水培条件下进行种子萌发,待小麦幼苗长至15cm时,对小麦幼苗进行NaCl胁迫培养,同时接种紫茎泽兰(Crofton Weed)根分离到的1株内生细菌,通过测定小麦叶片Pro(脯氨酸)和MDA(丙二醛)含量、PPO(多酚氧化酶)和CAT(过氧化氢酶)活性变化,探究内生细菌对NaCl胁迫培养后小麦的缓解作用.结果表明:NaCl胁迫培养条件下接种紫茎泽兰内生细菌后,小麦叶片CAT活性及Pro含量增加;小麦叶片PPO活性及MDA含量变化没有明显规律性,低盐(NaCl 150mmol/L)胁迫培养时接种紫茎泽兰内生细菌短时间内(本试验为7d)对小麦生长有缓解作用,说明紫茎泽兰内生细菌对NaCl(150mmol/L)胁迫培养的小麦幼苗生长有一定的修复作用,紫茎泽兰内生细菌在高盐(NaCl 300mmol/L)条件下生长繁殖受抑制.     

A study on the transmission of salivarian trypanosomes isolated from wild tsetse flies

Summary In two distinct areas of East Africa 28,238 and 16,303 non-teneral flies respectively were caught. Infected probosces containing mature trypanosome infections were macerated and inoculated into laboratory animals. Differences in the transmission of trypanosomes existed between different species of tsetse fly. The effect on transmission of trypanosome infection rate in the fly and species of host on which the flies fed is discussed. A method to estimate trypanosome challenge is proposed.

---

Sumario Se atraparon 28,238 y 16,303 moscas tsetse respectivamente en dos areas didtintas de Africa Oriental. Se maceraron proboscis infectadas con tripanosomas maduros y fueron inoculadas en animales de laboratorio. Existieron diferencias en la trasmisión de tripanosomas entre las distintas especies de moscas tsetse. Se discute el efecto obtenido sobre la transmisión por el grado de infección con tripanosomas en la mosca y en hospederos de los cuales la mosca se alimenta.

---

Résumé On a capturé dans deux régions différentes de l'Afrique de l'Est respectivement 28.238 et 16.303 mouches ayant pris au moins un repas. Les trompes infestées, contenant des trypanosomes métacycliques, ont été macérées et inoculées á des animaux de laboratoire. Il existait des différences dans la transmission de trypanosomes entre différentes espéces de glossines. L'effet sur la transmission du taux de l'infection á trypanosomes chez la mouche et l'espèce d'h?te sur lequel les mouches s'étaient nourries est discuté. On propose une méthode pour estimer l'intensité des inoculations trypanosomiennes.

     

玉米花生间作对玉米光合特性及产量形成的影响

为了进一步揭示玉米花生间作体系中玉米间作产量优势的光合机理,于2010-2011年在河南科技大学试验农场研究了间作玉米功能叶的光-光响应曲线和光-CO₂响应曲线特点、荧光参数、叶绿素含量与构成、干物质积累及灌浆速率。结果表明:间作提高了玉米功能叶片的叶绿素含量,改变了叶绿素构成,显著提高了净光合速率,延缓衰老;间作提高了玉米光补偿点、光饱和点、光饱和时的最大净光合速率、表观量子效率和羧化效率,显著降低了CO₂补偿点;PSⅡ的实际光化学效率、PSⅡ的最大光化学效率和光化学猝灭系数变化不明显。间作明显提高玉米生育后期单株干物质,主要在于促进了籽粒的生长,显著提高玉米产量, 偏土地当量(PLER-M)高于其所占面积比例的106.6%-120.3%,表现出明显的间作产量优势。这说明间作玉米产量间作优势主要来源于其生育后期净光合速率的提高,促进光合物质向籽粒的分配,净光合速率的提高是通过羧化效率和表观量子效率的提高,增强CO₂的固定能力实现的,而非是光能传递、转化效率的提高。     

An epidemiological study of gastrointestinal parasites of dogs from Southern Greater Buenos Aires (Argentina): age, gender, breed, mixed infections, and seasonal and spatial patterns

A total of 2193 fecal samples from owned dogs were collected during the 2003-2004 period in Southern Greater Buenos Aires, and were evaluated for the presence of intestinal parasites by a flotation-centrifugation method. The overall prevalence was 52.4%, and the 11 species found were: Ancylostoma caninum (13%), Isospora ohioensis complex (12%), Toxocara canis (11%), Trichuris vulpis (10%), Sarcocystis sp. (10%), Giardia duodenalis (9%), Isospora canis (3%), Hammondia-Neospora complex (3%), Dipilydium caninum (18 cases), Cryptosporidium sp. (5 cases), and Toxascaris leonina (1 case). There was no significant difference in the overall prevalence between genders (female = 50.4%, male = 54.6%), and breeds (pure = 52.3%, mixed = 53%), but prevalence in puppies (<1 year) was higher than in adult dogs (62.7% versus 40.8%, respectively). Only the prevalence of A. caninum differed between genders, with higher values for males. The prevalences of six of the parasite species showed a decreasing trend with increasing host age, and an inverse pattern was found for two other species. The prevalences of three protozoa were significantly higher in pure-breed dogs, and those of two nematodes were significantly higher in mixed-breed dogs. The prevalences of T. canis, A. caninum, and T. vulpis were spatially heterogeneous with a clear Southwest-Northeast gradient. Only prevalences of Sarcocystis sp. and G. duodenalis showed seasonal variation. The frequency distribution of the number of species per fecal sample did not differ from a random distribution. Results obtained throughout the world were discussed.     

Dirofilariasis in Argentina: historical review and first report of Dirofilaria immitis in a natural mosquito population

Argentina is one of the four South American countries where the presence of Dirofilaria immitis is currently confirmed. The objective of this study was to review information on dirofilariasis in the country, and to report our recent findings on mosquito vectors. Since the first report of dogs with unidentified microfilariae in 1926, D. immitis was found in seven provinces and canine prevalence ranged 0-71% at local scale. National prevalence was 8% by the end of the 1980s and current information is available only for Buenos Aires Province. Four pulmonary human infections of D. immitis and one subcutaneous of Dirofilaria sp. were documented. The common coati was the only wild host found, and natural infection in mosquitoes was not previously reported in the country. In our recent mosquito survey in Greater Buenos Aires, we captured and dissected 2380 mosquitoes belonging to 20 species. According to a minimum temperature of 14 degrees C, the potential transmission period (PTP) for D. immitis in Buenos Aires covers 6 months, and the most favourable period (mean temperature above 20 degrees C) takes place from the middle of November to the beginning of April. To identify potential vectors of the parasite, we assessed weekly abundances of mosquito species during those PTP estimated previously. We found two specimens of Culex pipiens and one of Aedes aegypti carrying non-infective stages of D. immitis. These two highly anthropophilic mosquitoes may enhance the role of D. immitis as zoonotic agent in temperate Argentina.     

Genetic structure and diversity of India hybrid tea

The most important evolutionary event in the success of commercial tea cultivation outside China in ~30 countries came about by the origin of India hybrid tea in India, derived from the extensive spontaneous hybridization that took place between the Assam type tea growing in the forest regions of Assam, North-East India and China type tea introduced from China in ~1875 to many regions of North-East India. The release of an enormous pool of vigorous and highly variable plants of India hybrid tea in North-East India was a significant step forward for the origin and evolution of tea as a highly successful crop plant. The 1,644 accessions and clones of India hybrid tea, representatives of known 15 morphotypes, were screened by 412 AFLP markers amplified by 7 AFLP primer pair combinations. All the 412 genetic loci were polymorphic across the 1,644 accessions and clones. The analysis was done with distance (PCoA and NJ) methods, and the STRUCTURE (Bayesian) model. Both PCoA and NJ analysis clustered 1,644 tea accessions and clones into six major groups with one group in each, constituted mostly by China hybrid, Assam China hybrid and Assam hybrid morphotypes, of distinct genetic identity. No group was exclusive for any particular morphotype. The accessions and clones belonging to morphotypes, Assam type, Assam hybrid, China hybrid and China Cambod were distributed in all the groups. It is the Assam type/Assam hybrid morphotypes which exhibit much broader genetic variability than in China type/China hybrid/Cambod type/Cambod hybrid morphotypes. The STRUCTURE analysis inferred 16 populations (K = 16), for which the greatest values of probability were obtained. Nine of the 16 clusters were constituted by the tea accessions and clones of ‘pure’ ancestry. The remaining clusters were of ‘mixed’ ancestry. This analysis provides evidence that the accessions and clones of the same morphotype are not always of same genetic ancestry structure. The tea accessions and clones obtained from outside North-East India shared the same groups (distance method) and clusters (STRUCTURE model) which were constituted by North-East India accessions. The present study also demonstrates very narrow genetic diversity in the commercial tea clones vis-à-vis the profound genetic diversity existing in the tea accessions. These clones were distributed in hardly two of the six groups in NJ tree. The identified 105 core accessions and clones, capturing 98% diversity, have their origin from almost all groups/subgroups of NJ tree.