Ultrastructural and immunocytochemical analysis of the circumferential microfilament bundle in avian retinal pigmented epithelial cells in vitro

Summary The dedifferentiated phenotype of pigmented epithelial cells in vitro is bipotential and is effected by environmental alterations mediated by the cell surface and associated cytoskeleton. We have begun an investigation into the role that contractile microfilaments play in maintaining cell contact and cell shape in retinal pigmented epithelial cells in vitro. In this paper, we report a structural analysis of the intersection of the circumferential microfilament bundle with the cell membrane of cultured pigmented epithelial cells from chick retina. Techniques of electron microscopy, including freezefracturing and deep-etching, reveal that microfilaments of this bundle associate with a junctional complex in the apical cell compartment and with membrane domains which are not components of the junction. Microfilaments link with the cell membrane either at their termini or along the membrane-apposed surface of the circumferential bundle. Furthermore, we report the immunocytochemical localization of filamin (a high molecular weight actin-binding protein, which forms fiber bundles and sheet-like structures when bound with Factin in solution) in the circumferential/microf相似文献   

Alternative transmission pathways for guinea worm in dogs: implications for outbreak risk and control

Guinea worm (Dracunculus medinensis) has exerted a high human health burden in parts of Africa. Complete eradication of Guinea worm disease (dracunculiasis) may be delayed by the circulation of the parasite in domestic dogs. As with humans, dogs acquire the parasite by directly ingesting infected copepods, and recent evidence suggests that consuming frogs that ingested infected copepods as tadpoles may be a viable transmission route (paratenic route). To understand the relative contributions of direct and paratenic transmission routes, we developed a mathematical model that describes transmission of Guinea worm between dogs, copepods and frogs. We explored how the parasite basic reproductive number (R₀) depends on parameters amenable to actionable interventions under three scenarios: frogs/tadpoles do not consume copepods; tadpoles consume copepods but frogs do not contribute to transmission; and frogs are paratenic hosts. We found a non-monotonic relationship between the number of dogs and R₀. Generally, frogs can contribute to disease control by removing infected copepods from the waterbody even when paratenic transmission can occur. However, paratenic transmission could play an important role in maintaining the parasite when direct transmission is reduced by interventions focused on reducing copepod ingestion by dogs. Together, these suggest that the most effective intervention strategies may be those which focus on the reduction of copepods, as this reduces outbreak potential irrespective of the importance of the paratenic route.     

Panicum maximum (Jacq.) density effect upon macrofauna structure in sediments of pilot-scale vertical flow constructed wetlands treating domestic wastewater

Plant density may have an impact on macrofauna structure in constructed wetlands (CW). In this study, Panicum maximum density effect on macrofauna structure in pilot-scale vertical flow CW treating domestic wastewater was estimated. Two beds were planted with P. maximum at 10 roots/m² (low density) and two others at 20 roots/m² (high density). Two unplanted beds were used as controls. After six months of wastewater treatment, macrofauna was collected by taking five cores of sediment samples at the corners and the centre of each bed following three layers in the vertical profile. Plant density seems not to impact significantly the CW performance. However, the plant density of 10 roots/m² (low density) provided higher wastewater treatment efficiency. Concerning macrofauna, 11 taxa belonging to 6 classes and 11 orders were collected. Macrofauna was significantly more diversified in the planted beds than in the control. But the two plant densities investigated do not show significant difference between macrofauna diversity of the planted beds. Macrofauna abundance was two- and three-fold higher, respectively, in the planted beds at high and low densities than in the controls. From the upper surface to the bottom of the beds, macrofauna diversity and abundance decreased, and were heavily dominated by Annelida.     

Examination of microbial fuel cell start-up times with domestic wastewater and additional amendments

Rapid startup of microbial fuel cells (MFCs) and other bioreactors is desirable when treating wastewaters. The startup time with unamended wastewater (118 h) was similar to that obtained by adding acetate or fumarate (110-115 h), and less than that with glucose (181 h) or Fe(III) (353 h). Initial current production took longer when phosphate buffer was added, with startup times increasing with concentration from 149 h (25 mM) to 251 h (50 mM) and 526 h (100 mM). Microbial communities that developed in the reactors contained Betaproteobacteria, Acetoanaerobium noterae, and Chlorobium sp. Anode biomass densities ranged from 200 to 600 μg/cm² for all amendments except Fe(Ш) (1650 μg/cm²). Wastewater produced 91 mW/m², with the other MFCs producing 50 mW/m² (fumarate) to 103 mW/m² (Fe(III)) when amendments were removed. These experiments show that wastewater alone is sufficient to acclimate the reactor without the need for additional chemical amendments.     

Ovarian activity reversibility after the use of deslorelin acetate as a short-term contraceptive in domestic queens

The objective was to evaluate ovarian activity reversibility in domestic queens after short-term contraceptive treatment with deslorelin acetate. Ten mature queens were used. In all queens, the estrous cycle was evaluated every 72 h by vaginal cytology (VC) and behavior assessments. When queens had VC characteristic of interestrus or diestrus, one deslorelin acetate implant (4.7 mg) was placed in the subcutaneous tissue of the interscapular region (day of insertion = Day 0). Thereafter, VC was performed every 48 h and on Day 90, implants were removed. At Day 100, estrus and ovulation were induced with 100 IU eCG (im), followed by 100 IU hCG (im), 84 h later (Day 103.5). Queens were ovariohysterectomized on Day 106. Corpora lutea (CL) were counted, oviducts were flushed, and oocytes were identified, isolated and stained to assess viability. In all queens, blood samples for plasma progesterone concentrations were collected once a week, from Days −21 to 106. After deslorelin acetate application, four queens had VC and behavior typical of estrus, and one ovulated. Furthermore, ovulation occurred in three queens that did not have VC or behavior consistent with estrus. After the initial ovarian stimulation, all females had anestrous VC during the deslorelin treatment period. Implants were readily removed. Following implant removal, all females responded to treatments to induce estrus and ovulation. There were (mean ± SEM) 13.1 ± 5.5 CL and 8.1 ± 5.5 oocytes per queen; the oocyte recovery rate was 56.8 ± 25.4% and all recovered oocytes were viable. We concluded that deslorelin acetate can be used as a reversible short-term contraceptive in domestic cats, because estrus and ovulation were successfully induced following implant removal.     

Treatment of mixed domestic–industrial wastewater using cyanobacteria

Alexandria Sanitary Drainage Company (ASDCO), Alexandria, Egypt has two primary treatment plants, the eastern and the western wastewater treatment plants (EWTP and WWTP) that receive mixed domestic–industrial influents and discharge into L. Mariut. The lake is subjected therefore to severe levels of pollution and dominated by members of cyanobacteria that can cope with the high pollution load in the lake water. Isolation and utilization of the locally generated cyanobacterial biomass for remediation processes of highly toxic pollutants offers a very efficient and cheap tool for governmental or private industrial activities in Alexandria and will generate a source of revenue in Egyptian localities. The main objective of the present study was to investigate the biodegradation and biosorption capacity of some potential cyanobacterial species dominating the lake ecosystem toward organic and inorganic contaminants polluting the primary-treated effluents of the EWTP and WWTP. The primary effluents were subjected to biological treatment using three axenic cyanobacterial strains (Anabaena oryzae, Anabaena variabilis and Tolypothrix ceytonica) as batch system for 7 days. Removal efficiencies (RE) of the different contaminants were evaluated and compared. Results confirmed the high efficiencies of the investigated species for the removal of the target contaminants which were species and contaminant-dependent. BOD₅ and COD recorded 89.29 and 73.68% as maximum RE(s) achieved by Anabaena variabilis and Anabaena oryzae, respectively. The highest RE of the TSS recorded 64.37% achieved by Tolypothrix ceytonica, while 38.84% was recorded as the highest TSD RE achieved by Anabaena variabilis. Tolypothrix ceytonica also exhibited the highest RE for FOG recorded 93.75%. Concerning the contaminant metals, Tolypothrix ceytonica showed the highest biosorption capacity where 86.12 and 94.63% RE were achieved for Zn and Cu, respectively. In conclusion, results of the present study confirmed the advantageous potential of using the tested cyanobacterial species for the treatment of contaminated wastewater. Results also clearly showed the quality improvement of the discharged wastewater which in turn will eliminate or at least minimize the expected deterioration of the receiving environment.     

Computer-assisted sperm analysis of fresh epididymal cat spermatozoa and the impact of cool storage (4 degrees C) on sperm quality

Epididymal cat sperm is commonly used for in vitro fertilization. Because of the high variability in preparation protocols and methods of evaluation, sperm quality may vary considerably between experiments and laboratories. The aims of the present study were (1) to describe an epididymal sperm preparation protocol to produce clean, highly motile samples using density gradient centrifugation, (2) to provide reference values of computer-assisted semen analysis (CASA) parameters of fresh epididymal cat sperm after density gradient centrifugation and (3) to investigate the effect of cool storage on various spermatozoa characteristics. After slicing the epididymides, viable and motile sperm cells were isolated using Percoll^® centrifugation. Sperm motility parameters were subsequently assessed using CASA in experiment 1. In experiment 2, fresh (day 0) sperm samples were evaluated for motility parameters (HTR) and stained for assessment of acrosomal status (FITC-PSA), morphology (eosin/nigrosin (E/N)), membrane integrity (E/N and SYBR^®14-PI) and DNA fragmentation (TUNEL). After addition of a Tris–glucose-citrate diluent containing 20% egg yolk, samples were cooled to 4 °C and reassessed on d1, d3, d5, d7 and d10. Cool storage impaired most motility and velocity parameters: MOT, PMOT, VAP, VSL, VCL, BCF, RAPID and the percentage of normal spermatozoa showed a decrease over time (P < 0.05) as compared to fresh samples. In contrast, STR, ALH, membrane integrity, DNA fragmentation and the percentage of acrosome intact spermatozoa were not affected by cool storage. However, the influence of cool storage of cat spermatozoa on subsequent in vitro embryo development and quality after IVF requires further investigation.     

家畜体细胞克隆中核重编程机理研究进展

体细胞克隆在绵羊、山羊、牛、猪等家畜中获得了成功,但目前的克隆效率非常低。克隆效率低使家畜体细胞克隆技术在畜牧业生产及其他领域的应用受到极大的限制,问题的根源在于对体细胞克隆中核重编程的分子机理缺乏了解。供体细胞核移入去核的卵母细胞后,必须经过后成表观遗传修饰的重编程,从而恢复供体细胞核的全能性,才能保证重构胚的正常发育及个体的正常生长。本文从移植核的重构、DNA甲基化总体改变、组蛋白修饰、X染色体失活、端粒长度和端粒酶活性恢复、印迹基因及其他与发育相关基因的表达及核重编程的影响因素等几个方面探讨了体细胞克隆中的核重编程机理,为克隆效率提高的方法研究提供理论依据。     

低聚乳果糖酶法制备的研究进展

低聚乳果糖是一种新型功能性低聚糖,是双歧杆菌的有效增殖因子。本文主要介绍了低聚乳果糖国内外研究状况、产品类型、安全性;重点介绍低聚乳果糖酶法制备方法,微生物来源,现有酶的改造修饰,并对制约低聚乳果糖发展的瓶颈问题简单概述。     

Urban domestic gardens (II): experimental tests of methods for increasing biodiversity

The extent and continued expansion of urbanisation has focused attention on the significance for native biodiversity of those green spaces remaining within such areas and the most appropriate methods of managing them. In the UK, a high proportion of urban space is comprised of the private or domestic gardens associated with residential dwellings, and many recommendations have been made for simple changes to improve their value for biodiversity (wildlife gardening). Here, we report the results of replicated experimental tests of five such common recommendations, involving the introduction to gardens of (i) artificial nest sites for solitary bees and wasps; (ii) artificial nest sites for bumblebees; (iii) small ponds; (iv) dead wood for fungi and other saproxylic organisms; and (v) patches of nettles Urtica dioica L. for butterfly larvae. The broad conclusion is that whilst some methods for increasing the biodiversity of garden environments may be very effective, others have a low probability of success on the timescales and spatial scales likely to be acceptable to many garden owners. If one of the functions of small scale biodiversity enhancement is to develop and encourage awareness of biodiversity and its conservation, then encouragement to conduct particular activities must be balanced with a realistic appraisal of their likely success.