FISH ASSEMBLAGE RESPONSES TO DIFFERENT SECONDARY CHANNEL DESIGNS IN THE LOWER MISSISSIPPI RIVER,U.S.A.:A TEMPLATE FOR RIVER RESTORATION

The lower Mississippi River(LMR) has been heavily modified for multiple human purposes such as navigation, flood control, and bank stabilization. However, the LMR simultaneously supports a diverse fish fauna that includes recreational and commercial fisheries. Due to river training and diversion structures constructed during the past 80 years, the historic characteristics of the LMR have been drastically altered and have likely influenced fishes and fisheries in the system. One common restoration measure used throughout the LMR has been to "notch" wing-dike structures that close secondary(side) river channels. Dike notching allows year-round flows through secondary channels, which enhances habitat diversity and promotes biological productivity at the ecosystem scale. Although notching is presumed good for LMR fishes and other biota, few studies have examined its effects on fish assemblages. In this study, fish assemblages were sampled at seven LMR secondary channels spanning from river kilometer(rkm) 628(Louisiana-Mississippi, U.S.A.) upstream to rkm 1504(Missouri-Kentucky, U.S.A.). Four secondary channels were termed "permanent"(i.e.,with notched dikes) while three secondary channels were termed "temporary"(i.e., without notched dikes).Fishes were sampled by boat-mounted electrofishing conducted during falling and low stages from1995—1997. Fish assemblages differed between permanent and temporary secondary channels, and varied somewhat between falling and low stages. Gizzard shad(Dorosoma cepedianum), threadfin shad(D. petenense), and white bass(Morone chrysops) demonstrated consistent preferences for low-current conditions associated with temporary secondary channels. Conversely, blue catfish(Ictalurus furcatus), flathead catfish(Pylodictis olivaris), and freshwater drum(Aplodinotus grunniens) were more associated with permanent secondary channels. Future restoration strategies in the LMR should consider dike notching and resultant maintenance of permanent secondary channels in selected river reaches. However, temporary secondary channels also contain unique fish species, and also appear to be important sites of riverine primary production. Restoration strategies should consider a balance of both secondary channel types, which should support the greatest biodiversity for the LMR ecosystem.     

微生物在水环境污染物降解中的应用

每年有大量来自工业、农业、养殖业和城市污水处理厂的废水被排入到水环境中,因此,地球上的水环境面临大量来自生活废水、工农业废水、非法排放的废水及其它废水的污染物质(如抗生素、杀虫剂,除草剂、烃等)的严重挑战,特别是近年来随着集约化养殖的发展,废水污染问题日益突出,并且随着分析手段的进步,能够检测到被排入水环境中的化学污染物质也越来越多,这些化学污染物对水环境中的生物产生有害影响.但是,微生物在污染控制上具有许多重要的作用.因此,本文对微生物在水环境污染物降解中的应用进行了评论.结果表明微生物主要是应用在水产养殖水中,而在其它的水体系(如河、湖、海)的应用较少.     

Effects of environmental stressors on stem cells

Environmental toxicants are ubiquitous,and many are known to cause harmful health effects.However,much of what we know or think we know concerning the targets and long-term effects of exposure to environmental stressors is sadly lacking.Toxicant exposure may have health effects that are currently mischaracterized or at least mechanistically incompletely understood.While much of the recent excitement about stem cells(SCs)focuses on their potential as therapeutic agents,they also offer a valuable resource to give us insight into the mechanisms and risks of toxicant effects.Not only as a response to the increasing ethical pressure to reduce animal testing,SC studies allow us valuable insight into the true effects of human exposure to environmental stressors under controlled conditions.We present a review of the history of publications on the effects of environmental stressors on SCs,followed by a consolidation of the literature over the past five years on a subset of key environmental stressors of importance to human health and their effects on both embryonic and tissue SCs.The review will make constructive suggestions as to areas of toxicant research where further studies are needed,as well as making indications of the potential utility for advancing knowledge and directing research on environmental toxicology.     

走进内蒙

2015年8月1日,我们每一个人收拾好行囊,整装待发,在邓涛老师带领下踏上了去往内蒙古的征程,拉开了探索灰色生命之旅的序幕. 队伍由两辆车、8人组成,我们早晨7点从中国科学院古脊椎动物与古人类研究所出发,披着清晨的阳光,摆脱城市的拥挤,缓缓地“逃离”了北京城.直到抵达张北之后我们的车子才能像矫健的马儿一样驰骋在广袤的公路上,沿途没有了城市的喧闹,没有了交通的堵塞,伴随我们的只有那一眼望去蓝蓝的天空、随风摆动的小草,以及那迷人的风景,偶尔打开车窗,一股凉爽的清风扑面而来,沁人心脾.经过一路的颠簸,我们在傍晚时刻到达锡林浩特,当地文物保护站的同志为我们安顿好了一切.     

例谈2007年高考"现代生物科技专题"

通过现代生物科技专题及相关高考试题的介绍与分析,以开拓学生视野,增强科技意识,激发学生探索生命奥妙和热爱生物科学的情感,为进一步学习现代生物学奠定基础.同时,借助现代生物科技专题作试题背景,具有能力的开放性和情境的新颖性,也有利于考查和培养学生独立获取新知识、收集和处理信息的能力.所选试题涉及现代生物科技前沿的领域有:基因工程、细胞工程、蛋白质工程、癌症和克隆技术等,均体现出对现代生物技术发展的关注.     

Formidable females redux:male social integration into female networks and the value of dynamic multilayer networks

The development of multilayer network techniques is a boon for researchers who wish to understand how different interaction layers might influence each other,and how these in turn might influence group dynamics.Here,we investigate how integration between male and female grooming and aggression interaction networks influences male power trajectories in vervet monkeys Chlorocebus pygerythrus.Our previous analyses of this phenomenon used a monolayer approach,and our aim here is to extend these analyses using a dynamic multilayer approach.To do so,we constructed a temporal series of male and female interaction layers.We then used a multivariate multilevel autoregression model to compare cross-lagged associations between a male's centrality in the female grooming layer and changes in male Elo ratings.Our results confirmed our original findings:changes in male centrality within the female grooming network were weakly but positively tied to changes in their Elo ratings.However,the multilayer network approach offered additional insights into this social process,identifying how changes in a male's centrality cascade through the other network layers.This dynamic view indicates that the changes in Elo ratings are likely to be short-lived,but that male centrality within the female network had a much stronger impact throughout the multilayer network as a whole,especially on reducing intermale aggression(i.e.,aggression directed by males toward other males).We suggest that multilayer social network approaches can take advantage of increased amounts of social data that are more commonly collected these days,using a variety of methods.Such data are inherently multilevel and multilayered,and thus offer the ability to quantify more precisely the dynamics of animal social behaviors.     

Plant infection by two different viruses induce contrasting changes of vectors fitness and behavior

Insect-vectored plant viruses can induce changes in plant phenotypes,thus influencing plant-vector interactions in a way that may promote their dispersal according to their mode of transmission (i.e.,circulative vs.noncirculative).This indirect vector manipulation requires host-virus-vector coevolution and would thus be effective solely in very specific plant-virus-vector species associations.Some studies suggest this manipulation may depend on multiple factors relative to various intrinsic characteristics of vectors such as transmission efficiency.In anintegrative study,we tested the effects of infection of the Brassicaceae Camelina sativa with the noncirculative Cauliflower mosaic virus (CaMV)or the circulative Turnip yellows virus (TuYV)on the host-plant colonization of two aphid species differing in their virus transmission efficiency:the polyphagous Myzus persicae,efficient vector of both viruses,and the Brassicaceae specialist Brevicoryne brassicae,poor vector of TuYV and efficient vector of CaMV.Results confirmed the important role of virus mode of transmission as plant-mediated effects of CaMV on the two aphid species induced negative alterations of feeding behavior (i.e.,decreased phloem sap ingestion)and performance that were both conducive for virus fitness by promoting dispersion after a rapid acquisition.In addition,virus transmission efficiency may also play a role in vector manipulation by viruses as only the responses of the efficient vector to plant-mediated effects of TuYV,that is,enhanced feeding behavior and performances,were favorable to their acquisition and further dispersal.Altogether,this work demonstrated that vector transmission efficiency also has to be considered when studying the mechanisms underlying vector manipulation by viruses.Our results also re- inforce the idea that vector manipulation requires coevolution between plant,virus and vector.     

Increased monoamine oxidase activity and imidazoline binding sites in insulin-resistant adipocytes from obese Zucker rats

BACKGROUND Despite overt insulin resistance,adipocytes of genetically obese Zucker rats accumulate the excess of calorie intake in the form of lipids.AIM To investigate whether factors can replace or reinforce insulin lipogenic action by exploring glucose uptake activation by hydrogen peroxide,since it is produced by monoamine oxidase(MAO)and semicarbazide-sensitive amine oxidase(SSAO)in adipocytes.METHODS 3H-2-deoxyglucose uptake(2-DG)was determined in adipocytes from obese and lean rats in response to insulin or MAO and SSAO substrates such as tyramine and benzylamine.14C-tyramine oxidation and binding of imidazolinic radioligands[3H-Idazoxan,3H-(2-benzofuranyl)-2-imidazoline]were studied in adipocytes,the liver,and muscle.The influence of in vivo administration of tyramine+vanadium on glucose handling was assessed in lean and obese rats.RESULTS 2-DG uptake and lipogenesis stimulation by insulin were dampened in adipocytes from obese rats,when compared to their lean littermates.Tyramine and benzylamine activation of hexose uptake was vanadate-dependent and was also limited,while MAO was increased and SSAO decreased.These changes were adipocyte-specific and accompanied by a greater number of imidazoline I2 binding sites in the obese rat,when compared to the lean.In vitro,tyramine precluded the binding to I2 sites,while in vivo,its administration together with vanadium lowered fasting plasma levels of glucose and triacylglycerols in obese CONCLUSION The adipocytes from obese Zucker rats exhibit increased MAO activity and imidazoline binding site number.However,probably as a consequence of SSAO down-regulation,the glucose transport stimulation by tyramine is decreased as much as that of insulin in these insulin-resistant adipocytes.The adipocyte amine oxidases deserve more studies with respect to their putative contribution to the management of glucose and lipid handling.     

Stem cell therapy applied for digestive anastomosis: Current state and future perspectives

BACKGROUND Digestive tract resections are usually followed by an anastomosis.Anastomotic leakage,normally due to failed healing,is the most feared complication in digestive surgery because it is associated with high morbidity and mortality.Despite technical and technological advances and focused research,its rates have remained almost unchanged the last decades.In the last two decades,stem cells(SCs)have been shown to enhance healing in animal and human studies;hence,SCs have emerged since 2008 as an alternative to improve anastomoses outcomes.AIM To summarise the published knowledge of SC utilisation as a preventative tool for hollow digestive viscera anastomotic or suture leaks.METHODS PubMed,Science Direct,Scopus and Cochrane searches were performed using the key words“anastomosis”,“colorectal/colonic anastomoses”,“anastomotic leak”,“stem cells”,“progenitor cells”,“cellular therapy”and“cell therapy”in order to identify relevant articles published in English and Spanish during the years of 2000 to 2021.Studies employing SCs,performing digestive anastomoses in hollow viscera or digestive perforation sutures and monitoring healing were finally included.Reference lists from the selected articles were reviewed to identify additional pertinent articles.METHODS Given the great variability in the study designs,anastomotic models,interventions(SCs,doses and vehicles)and outcome measures,performing a reliable meta-analysis was considered impossible,so we present the studies,their results and limitations.RESULTS Eighteen preclinical studies and three review papers were identified;no clinical studies have been published and there are no registered clinical trials.Experimental studies,mainly in rat and porcine models and occasionally in very adverse conditions such as ischaemia or colitis,have been demonstrated SCs as safe and have shown some encouraging morphological,functional and even clinical results.Mesenchymal SCs are mostly employed,and delivery routes are mainly local injections and cell sheets followed by biosutures(sutures coated by SCs)or purely topical.As potential weaknesses,animal models need to be improved to make them more comparable and equivalent to clinical practice,and the SC isolation processes need to be standardised.There is notable heterogeneity in the studies,making them difficult to compare.Further investigations are needed to establish the indications,the administration system,potential adjuvants,the final efficacy and to confirm safety and exclude definitively oncological concerns.CONCLUSION The future role of SC therapy to induce healing processes in digestive anastomoses/sutures still needs to be determined and seems to be currently far from clinical use.     

向日葵生殖生长不同时期向光运动日变化的观察

通过观测可以确定向日葵的确具有明显跟随太阳旋转的向光性,但处于不同时期的向日葵有很大差异:处于花蕾早期的向日葵从日出到日落跟随太阳由东经南再向西运动且有明显的滞后现象.盛花期的向日葵花盘基本固定朝向东方,不跟随太阳运动,但仍有小范围偏转.     

Vaginal smear cycle in 4-day cyclic Chinese hamsters, Cricetulus griseus]

The contents of vaginal smear of 4-day cyclic Chinese hamster (Cricetulus griseus) was investigated every 3 hours for 5 days. A light-dark cycle of 14--10 hr was used with the lights turned on at 6 : 00 a.m. Estrous cycle of the Chinese hamster determined by vaginal smears can be divided into 6 periods. The proestrous phase started at about 0 : 00 of day 1, the day of the proestrous phase was designated as day 1 of the estrous cycle. In the afternoon of the same day 1, nucleated epithelial cells gradually increased in number (proestrus : I), and the vaginal contents became to consist solely of nucleated epithelial cells at about 18 : 00 to 21 : 00 (estrus : II). At about 0 : 00 of day 2, however, nucleated epithelial cells were superseded suddenly by cornified epithelial cells, and this phase lasted for 9 to 12 hr (metestrus I : III). Towards the end of the cornified stage, nucleated cells appeared in short duration (metestrus II : IV). And then, in the evening of day 2, leucocytes gradually increased in number with degeneration of nucleated cells (diestrus I : V-1). On day 3, vaginal smear contained a large amount of mucus as well as degenerated nucleated cells and leucocytes (diestrus II : V-2). At about 21 : 000 of day 4, some cornified epithelial cells were seen and then proestrous stage was returned. The females were mated with 3 to 5 males in the evening of day 1, copulation was confirmed in 83.7% females in the next morning,thus the copulation in the Chinese hamster may be thought to occur during the vaginal smear stage of nucleated epithelial cells (estrous phase), i.e. about 18 : 00 to 24 : 00 of day 1.     

Relationship of Vaginal Cytology to Alterations of the Vaginal Microflora of Rats During the Estrous Cycle

The influence of cyclic changes occurring in the vaginal tract during the estrous cycle upon the indigenous microflora of the vagina has been investigated by semiquantitative techniques in virgin female rats. By plate counts performed on material lavaged daily from the vaginal tract of several rats, it is apparent that bacterial counts are elevated in the proestrus and estrus phases of the cycle to values several orders of magnitude greater than those observed during metestrus or diestrus phases. Increases in vaginal bacterial counts were associated with the presence of cornified epithelial cells in the vagina; these cells were predominantly nonviable. Decreases in the vaginal bacterial content were related to the influx of leukocytes into the vagina after estrus. When leukocytes were present in the vaginal tract, they were 90 to 100% viable. From these observations it has been concluded that the female vaginal tract and the bacteria which colonize it represent a dynamic ecosystem which is responsive to cyclic events occurring in the estrous cycle. The changing cellular content of the vaginal tract may have relevance to the observed cyclic changes in the bacterial content of the vagina.     

Performing Vaginal Lavage,Crystal Violet Staining,and Vaginal Cytological Evaluation for Mouse Estrous Cycle Staging Identification

A rapid means of assessing reproductive status in rodents is useful not only in the study of reproductive dysfunction but is also required for the production of new mouse models of disease and investigations into the hormonal regulation of tissue degeneration (or regeneration) following pathological challenge. The murine reproductive (or estrous) cycle is divided into 4 stages: proestrus, estrus, metestrus, and diestrus. Defined fluctuations in circulating levels of the ovarian steroids 17-β-estradiol and progesterone, the gonadotropins luteinizing and follicle stimulating hormones, and the luteotropic hormone prolactin signal transition through these reproductive stages. Changes in cell typology within the murine vaginal canal reflect these underlying endocrine events. Daily assessment of the relative ratio of nucleated epithelial cells, cornified squamous epithelial cells, and leukocytes present in vaginal smears can be used to identify murine estrous stages. The degree of invasiveness, however, employed in collecting these samples can alter reproductive status and elicit an inflammatory response that can confound cytological assessment of smears. Here, we describe a simple, non-invasive protocol that can be used to determine the stage of the estrous cycle of a female mouse without altering her reproductive cycle. We detail how to differentiate between the four stages of the estrous cycle by collection and analysis of predominant cell typology in vaginal smears and we show how these changes can be interpreted with respect to endocrine status.     

小鼠发情周期卵泡发育动态及其对超数排卵的影响

该文探讨了小鼠发情周期中阴门状态、阴道脱落细胞类型变化规律、卵泡发育规律及其相互关系,并比较了发情周期不同阶段的超排效果。结果表明,采用阴门状态观察法和阴道脱落细胞涂片法,能有效判断小鼠发情周期阶段。卵巢组织切片观察结果表明,在发情周期不同阶段,小鼠的卵泡发育和黄体的生成与消退存在明显的规律性变化;小鼠发情周期中,其阴门状态、阴道脱落细胞种类及卵泡发育动态之间存在相关关系;发情周期不同阶段开始超排的小鼠,其配种见栓率和回收胚胎平均数均存在明显差异,发情前期显著优于发情后期与间情期(P<0.05),并高于发情期,但差异不显著(P>0.05),即阴门状态观察法与阴道脱落细胞涂片法均可用于小鼠发情周期阶段的判断,发情前期为最适宜的小鼠超排时期。     

Effects of hCG on folliculogenesis and fecundity in mink (Mustela vision Schreb)

The endogenous hormonal response obtained after reproductive organs are challenged by exogenous hormones is increasingly being used to predict presence of functional reserves and to apply this information to improve efficiency of managed breeding programs. With that in mind, the aim of the present study was to investigate the effect of a single treatment with hCG on folliculogenesis and fertility in standard 7-month-old mink females. The extent of stimulation following treatment was determined by examining patterns of vaginal smears. Characteristics of each cycle stage were: estrus, preponderance of cornified epithelial cells; proestrus, polygonal, elongate epithelial cells; anestrus, parabasal, intermediate and leucocyte cells. Smears exhibiting a mixed population of cells were categorized as being in transition between adjacent stages anestrus–proestrus or proestrus–estrus. The initial evaluations were done on Day 6 after hCG treatment. Histomorphometric examination of ovaries and uteri was done during seasonal anestrus (November) and in the breeding season (March). Vaginal cytology patterns were correlated with changes in folliculogenesis. A mean of 1.3 mature (Graafian) follicles were counted during estrus, while the mean number seen during anestrus, anestrus–proestrus and proestrus, were 0.4, 0.3 and 1.0, respectively. During the breeding season, in females that were not treated, the numbers of growing follicles decreased and maturing follicles increased, whereas females that came in estrus after treatment with hCG in November had increased numbers of both growing and maturing follicles. Fertility after breeding in hCG-treated females was increased by 9.2% (P<0.05) as compared to untreated females. Females showing the highest fertility rise (27%) were predominantly in the group that showed estrus after hCG treatment. We conclude that monitoring the response of the mink reproductive system to hCG stimulation in November may be a useful tool for identifying females of high fertility in the spring.     

Regulation of the bacterial microflora of the vagina in cyclic female rats.

The bacterial microflora was examined in the vagina of cyclic female rats kept under normal laboratory conditions. Large variations occurred during the cycle with high numbers of bacteria (10(5)-10(8) per vagina) during proestrus and estrus and low numbers (10(1)-10(4) per vagina) during the diestrus period. Histological analysis of in situ vaginal tissue and transplanted vaginal tissue revealed an association of high bacterial numbers with the presence of large amounts of cellular debris in the vaginal lumen during the period of epithelial keratinization. Absence of phagocytosis in leucocytes at mestestrus suggested that leucocytes did not play an active role in reduction of bacterial numbers between estrus and metestrus. Accurate measurement of the pH in the vaginal lumen failed to reveal differences which could explain the reduction in bacterial numbers between estrus and metestrus. The cyclic changes in the bacterial population-consisting of species which are normally present in the intestinal flora-- seem to be controlled by cyclic changes in the amounts of cellular debris in the vaginal lumen.     

Hormone-sensitive lipase expression and IHC localization in the rat ovary, oviduct, and uterus

Hormone-sensitive lipase (HSL) is a key regulator of cholesterol esters metabolism. The aim of this study was to determine HSL localization in rat female reproductive organs during the ovarian cycle by IHC methods. HSL was located in the ovarian epithelium. The granulosa cells and oocytes of primordial follicles were immunonegative. In mature follicles, HSL was found in oocytes and theca and granulosa cells. However, HSL expression in theca cells and oocytes decreased during follicular atresia. Luteal cells showed HSL staining in cytoplasm during proestrus and estrus, in the nucleus during metestrus, and in cytoplasm and the nucleus during diestrus. In the tubaric ampulla, HSL was located in the epithelial cells nuclei and in the cilia during proestrus and estrus but mainly in the nucleus during metestrus and diestrus. In the isthmus, cells showed HSL immunolabeling in the nucleus and cilia during proestrus, but only in the cilia during estrus, metestrus, and diestrus. In the uterus, HSL was found in the epithelial cells nuclei. HSL-immunoreactive bands at 84, 67, 54, and 43 kDa were found in rat female reproductive organs. HSL labeling in the nucleus of epithelial and germ cells suggests an as yet unknown function for this protein, probably related to oogenesis and cell proliferation.     

Diffusion barriers in the vaginal epithelium during the estrous cycle in guinea pigs

Summary In the present study the permeability barriers of the multilayered vaginal epithelium were examined using tracer perfusion techniques, freeze-fracture and thin sectioning. During diestrus and proestrus the upper layers of mucified epithelial cells exhibit tight-junctional belts, which restrict tracer molecules such as lanthanum and horseradish peroxidase. When the highly mucified cells begin to degenerate toward the end of proestrus the underlying epithelium is already keratinized as typical for estrus. The keratinized epithelial cells have a tight-junctional network that joins the basal plasma membranes with the apical membranes of subjacent cells and blocks paracellular diffusion of the tracer molecules. During conversion of the cornified epithelium to a mucified epithelium in metestrus the intercellular space of the epithelium is stained by tracer molecules even though tight-junctional belts can be observed.These results indicate that during cyclic changes of the vaginal epithelium tight junctions can, in general, be considered for the restriction of paracellular diffusion. In metestrus, however, junctions become functionally leaky although they remain morphologically intact.Intercellular lipids, which are normally common in cornified epithelia, are extremely rare and cannot constitute an effective barrier to diffusion in the vagina of the guinea pig. The significance of a strategy that bases the regulation of the permeability on tight junctions rather than on intercellular lipids is discussed.     

Immunohistochemical detection of androgen receptors in the canine uterus throughout the estrus cycle

Serum androgen levels in the bitch increase during proestrus and remain elevated until metestrus. To find out whether androgens can have a direct impact on the canine uterus, androgen receptors (AR) were identified immunohistochemically in uterine tissue. Androgen receptor distribution in the uterine horns, body and cervix was described during different cycle stages, during pregnancy and in the postpartum period. Nuclear staining for AR was observed in cells of the surface epithelium, glandular ducts, basal glands and stroma of the endometrium, and in myometrial smooth muscle cells. In addition, cytoplasmic staining was observed in epithelial cells from proestrus to early metestrus, when the cells were secretory active, and in stroma cells during pregnancy, suggesting a role for androgens in decidualization. During pregnancy and in the postpartum period nuclear staining for AR was nearly absent. During the estrus cycle stroma cells stained with higher intensities for AR than epithelial cells, supporting the idea that stroma cells mediate some effects of steroid hormones on epithelial cells in the genital tract. In contrast with earlier findings on estrogen receptor-alpha and progesterone receptors, no significant changes in androgen receptor expression were observed during the estrus cycle. Few correlations were found between the staining for AR and serum levels of the sex steroids. The present findings suggest that there is a basal expression of AR in the canine uterus throughout the estrus cycle that may not be influenced by sex steroid hormones.