Fibroblast growth factor 2 and protein kinase C alpha are involved in syndecan-4 cytoplasmic domain modulation of turkey myogenic satellite cell proliferation

Syndecan-4 core protein is composed of extracellular, transmembrane, and cytoplasmic domains. The cytoplasmic domain functions in transmitting signals into the cell through the protein kinase C alpha (PKCα) pathway. The glycosaminoglycan (GAG) and N-linked glycosylated (N-glycosylated) chains attached to the extracellular domain influence cell proliferation. The current study investigated the function of syndecan-4 cytoplasmic domain in combination with GAG and N-glycosylated chains in turkey muscle cell proliferation, differentiation, fibroblast growth factor 2 (FGF2) responsiveness, and PKCα membrane localization. Syndecan-4 or syndecan-4 without the cytoplasmic domain and with or without the GAG and N-glycosylated chains were transfected or co-transfected with a small interfering RNA targeting syndecan-4 cytoplasmic domain into turkey muscle satellite cells. The overexpression of syndecan-4 mutants increased cell proliferation but did not change differentiation. Syndecan-4 mutants had increased cellular responsiveness to FGF2 during proliferation. Syndecan-4 increased PKCα cell membrane localization, whereas the syndecan-4 mutants decreased PKCα cell membrane localization compared to syndecan-4. However, compared to the cells without transfection, syndecan-4 mutants increased cell membrane localization of PKCα. These data indicated that the syndecan‐4 cytoplasmic domain and the GAG and N-glycosylated chains are critical in syndecan-4 regulating satellite cell proliferation, responsiveness to FGF2, and PKCα cell membrane localization.     

A quantitative ultramorphological approach for systematic assessment of sperm head regions: an example in rams

Examination of the type and frequency of damage to the head of spermatozoa using electron microscopy can be used to evaluate the quality of differently treated sperm. This report describes a systematic approach based on 29 morphological categories of sperm heads assessed from discrete regions in raw, chilled and frozen-thawed spermatozoa. Injury occurred principally at the plasma membrane and could be present or absent in all regions. In the anterior segment, when the plasma membrane is present, it can be intact, dilated, very dilated, disrupted, or contain vesicles characteristic of acrosomal reaction-like capacitation changes. When the plasma membrane is absent, the acrosome may be intact, exhibit a complete loss of contents, or retain some contents of the apical ridge and present a very dilated outer acrosomal membrane. The plasma membrane in the equatorial segment and the boundary between regions can be intact, dilated, very dilated or disrupted. The post-acrosomal plasma membrane is classified as intact, dilated or very dilated, whereas the dense lamina is intact, dilated or fragmented. The morphology of the heads most frequently observed in chilled spermatozoa consists of anterior and equatorial segments with a dilated, or dilated and disrupted plasma membrane; a boundary between regions with an intact and dilated plasma membrane; and a post-acrosomal region with an intact plasma membrane and dense lamina, both dilated. In frozen-thawed spermatozoa, the morphology of the heads is more frequently characterised by no plasma membrane and an acrosome showing complete or some loss of contents in the apical ridge and very dilated outer acrosomal membrane, presenting mostly dilated and fragmented dense lamina in the post-acrosomal region. These findings are consistent with the conclusion that the freezing process produces an increase in the degree of damage to the cells when they are subjected to increasing degrees of cold shock. There are still difficulties in developing a good diluent and process for preserving the plasma membrane in ram spermatozoa. This systematisation, using different categories, allows characterisation of multiple transmission electron microscopy images. Thus, the different changes observed due to cryopreservation may be correlated.     

CALLING SONG DISPLACEMENT IN A ZONE OF OVERLAP AND HYBRIDIZATION

The ground crickets Allonemobius fasciatus and A. socius meet in a mosaic zone of overlap and hybridization stretching from the East Coast to at least Illinois. To test whether male calling song differences were enhanced in sympatry, we analyzed the songs of crickets from inside and outside the zone of overlap along two transects. No evidence of calling song displacement was found in A. socius males from populations within the zone of overlap. On the other hand, A. fasciatus displayed calling song displacement in three populations. Our results are consistent with the hypothesis that the selective pressure exerted by the challenge from a related species is frequency dependent. While not a conclusive demonstration, the observed shifts in calling song are strongly suggestive of reproductive character displacement.     

宁夏灵武市沟眶象发生特点

系统调查沟眶象Eucryptorrhynchus chinensis(Olivier)在宁夏灵武市的发生情况和特点发现:沟眶象以成虫和幼虫在土壤中越冬,成虫有2个发生高峰期,越冬结束后以成虫越冬的沟眶象出土出现第1个高峰期,以幼虫越冬的沟眶象经化蛹羽化出土出现第2个高峰期;幼虫危害臭椿根部形成的瘤状物可以作为鉴别沟眶象危害的特征;沟眶象幼虫在土壤中垂直分布范围集中在0～45 cm深土层,约占80%;成虫出土孔集中在距臭椿树干基部75 cm范围内,占88%。据此建议土壤施药化学防治沟眶象时,施药深度不宜低于45 cm,施药点距树干基部水平距离不得少于75 cm,且树周各个方向均需施药。每年10月末沟眶象开始"入土"、翌年4月末开始"出土",在沟眶象"入土"结束后但未冻土之前的11中旬和土壤解冻之后但尚未"出土"前的4月中旬,这两个时期土壤施药防治效果较好;防治沟眶象的同时,还应适时采取打孔注药、熏蒸等措施防治臭椿(Ailanthus altissima(Mill.)Swingle)树干内的臭椿沟眶象Eucryptorrhynchus brandti(Harold)。     

Using space‐for‐time substitution and time sequence approaches in invasion ecology

1. Invasion biologists use two main approaches to evaluate the effects of non‐native species (NNS) on diversity of native species (DNS), namely space‐for‐time and time approaches. These approaches have pitfalls related to lack of controls: the former lacks pre‐invasion data, while the latter often lacks data from non‐invaded sites. 2. We propose a framework that combines space‐for‐time and time approaches and which should result in more focused mechanistic hypotheses and experiments to test the causes of invasibility and the effects of NNS on DNS. We illustrate the usefulness of our framework using two case studies: one with the submersed macrophyte, Hydrilla verticillata, in reservoir and the other with the fish, Geophagus proximus, in a large river–floodplain system. 3. Hydrilla verticillata invaded sites with DNS similar to that found in non‐invaded sites, indicating that biotic and/or abiotic factors did not influence invasion success; however, DNS increased over time in invaded sites compared with non‐invaded sites, suggesting that H. verticillata facilitated natives. In contrast, G. proximus invaded sites with higher DNS than non‐invaded sites, suggesting that biotic and/or abiotic factors favouring natives were important for invasion success, but DNS increased in invaded and non‐invaded sites over time, indicating that an independent factor contributed to DNS increases. 4. Conclusions from both studies would have been inaccurate or incomplete if the space‐for‐time and time approaches had not been used in combination as proposed in our framework.     

Isolation and characterisation of transposon-induced mutants of Erwinia carotovora subsp. atroseptica exhibiting reduced virulence

Summary The blackleg pathogen Erwinia carotovora subsp. atroseptica (Eca) causes an economically important disease of potatoes. We selected a genetically amenable Eca strain for the genetic analysis of virulence. Tn5 mutagenesis was used to generate nine mutants which exhibited reduced virulence (Rvi^-) of strain SCRI1043. Following physiological characterisation, mutants were divided into three classes: (1) auxotrophs; (2) extracellular enzyme mutants; and (3) a growth rate mutant. The isolation of these Rvi^- mutants has allowed us to consider some factors that affect Eca virulence.     

Complete maps of IS1, IS2, IS3, IS4, IS5, IS30 and IS150 locations in Escherichia coli K12

Summary In this paper complete distribution maps are presented of the seven IS elements 1, 2, 3, 4, 5, 30 and 150. These maps were obtained during the construction of an almost complete restriction map of the Escherichia coli genome of K12 strain BHB2600. The positions of IS elements were correlated to this map. The distribution of integration sites of all IS types is nonrandom. Besides a large gap from 79 min to 96 min, there is a pronounced IS cluster at 6 min and another at 97 min, map locations that have low gene incidences on the classical map. One cluster coincides with a region of IS induced rearrangements. The IS distribution pattern was compared to patterns of strains W3110 and HB101.     

Effect of abscisic acid on the photosynthetic oxygen evolution in barley chloroplasts

In vivo effect of abscisic acid (ABA) on photosynthetic oxygen evolution was investigated in barley chloroplasts. The most important kinetic parameters of O₂-producing reactions were changed. The results show inhibition of the O₂-flash yields at ABA concentrations of 10 mol/l and 100 mol/l and an increase in the degree of damping of the oscillations. ABA has a marked effect on the distribution of the oxygenevolving centers in S₀ and S₁ states and on sum of the centers (S₀+S₁) estimated according to the Kok model. In addition, the amplitude and the shape of the initial oxygen burst under continuous illumination are also significantly altered. At a concentration of 100 mol/l, ABA strongly inhibits Hill reaction activity measured by DCPIP reduction. The results cannot be explained by the hypothesis of socalled stomata effect. On the other hand, no effects were observed on the investigated parameters in experiments involving ABA applied in vitro to isolated chloroplasts. It is hypothesized that ABA disrupts the granal chloroplasts structure and raises the degree of participation of the cooperative mechanism of O₂-evolution connected with the functioning of PS II centers in the stroma situated thylakoids.Abbreviations DCPIP 2,6-Dichlorophenolindophenol - DCMU 3-(3,4-dichlorophenil)-1,1-dimethylurea - HEPES N-2-Hydroxyethylpiperazine-N-2-ethane sulfonic acid - PSII photosystem II - RubisCO Ribulose-1,5-bis-phosphate carboxylase-oxygenase     

四川围栏养殖林麝采食植物种类调查

对四川都江堰人工养殖围栏内林麝采食的野生及栽种植物种类进行调查.结果表明,围栏内共有林麝采食植物64种,隶属于31科,多属于农田野草、野菜,少数是栽种的饲草、树木.分析了林麝采食利用植物的特点及这些植物作为饲料在生产中的潜在应用价值.     

高速逆流色谱法同时分离制备头花蓼中没食子酸和原儿茶酸

对蓼科蓼属头状蓼组植物头花蓼进行化学成分的研究。本研究建立了HPLC测定中药头花蓼水提喷雾干燥粉末中化学成分含量的方法,然后应用高速逆流色谱法对头花蓼水提喷雾干燥粉末的乙酸乙酯粗提物的化学成分进行了半制备性分离研究,通过对分离方法和溶剂系统的筛选,寻找到最佳的溶剂系统(正己烷∶乙酸乙酯∶甲醇∶水=1∶5∶1∶5),上相为固定相,转速840 r/min,流速2.0 mL/min,进样量756 mg,检测波长272 nm。结果显示,在该条件下经一步分离可同时得到质量为148.5 mg和9.2 mg的两种产物,纯度为99.8%和97.4%,经紫外、红外、质谱及核磁共振等方法进行结构分析,确定分别为没食子酸和原儿茶酸。