The morphology of the male reproductive structures of Perionyx excavatus (Oligochaeta)

Perionyx excavatus (Oligochaeta) is a vermicomposting earthworm of which the reproductive strategies are little known. In order to obtain more information on this, its reproductive systems were studied. Existing literature on the topic is either contradictory or scant. The investigation was done by examining the gross anatomy and histology, using scanning and transmission electron microscopy_ The male reproductive system consists of two pairs of testes in segments 10 and 11 and two pairs of seminal vesicles in segments 11 and 12. In mature worms the developing spermatozoa are released by the testis into the body cavities of segments 10 and 11. The seminal vesicles in a particular segment receive developing spermatozoa from the lumen of the preceding segment. Two pairs of ciliated sperm funnels also occur in segments 10 and 11 and become the ciliated vasa deferentia carrying the sperm. The vasa deferentia on each side fuse to form only one vas deferens. These vasa deferentia reach the pair of prostatic glands in segment 18, each joining the prostatic duct and opening via the ventral male openings adjacent to each other on segment 18. Associated with the male openings are retractable penial chaetae. The cellular composition and organelle distribution of some organs and structures are also described. The positions of the female reproductive structures are illustrated diagrammatically in this paper.S. Afr. J. Zool. 1997,32(3

The morphology of the female reproductive structures of Penonyx excavatus (Oligochaeta)

Perionyx excavatus (Oligochaeta) is a vermicomposting earthworm of which little is known regarding its reproductive strategies. This rs a second paper by the authors on the morphology of the reproductive structures in an attempt to reconcile the scanty and confusing literature on this topic and to investigate the possibility of self-fertilization. The investigation was done by examining the gross anatomy and histology, using scanning and transmission electron microscopy. The female reproductive system consists of three pairs of spermathecae rn segments seven, eight and nine. Each spermatheca consists of one ampulla and four sessile diverticula. The spermathecae open separately but midventrally in the intersegmental groove anterior to the segments in which they occur. One pair of ovaries is found in segment 13 The ova are released into the body cavity and are collected by the two ciliated ovum funnels, also in segment 13. The two short oviducts leading from the ovaries, join into a common oviduct. The common oviduct opens into the female opening, which is situated midventrally, anterior to the ring of body chaetae on segment 14

Characterization of Antennas on Dielectric and Magnetic Substrates Effective Medium Approximation

This paper presents a study of the effective medium approximation of a monopole antenna printed on either a dielectric or a magnetic substrate. Simple analytical formulas to determine the effective permeability of such an antenna have been proposed and validated. For this type of antenna as μr increases, the effective permeability will reach the value of 2 (maximum) whereas, with the dielectric substrate, the effective permittivity continues to rise when increasing εr. This shows that, for very high permeability values, we will always have a size reduction below 30%

Short Communication: The rate of release of Cry1Ab protein from Bt maize leaves into water

Transgenic Bt maize plants are genetically modified to contain genes of Bacillus thuringiensis that encode for δ-endotoxins (Cry1Ab protein) that have insecticidal properties. These endotoxins target certain lepidopteran pests of maize. There are several entry routes by which Cry proteins enter the aquatic ecosystem in which aquatic organisms are exposed to these proteins. The main route is through plant debris such as leaves, stalks and postharvest detritus that are transported by means of run-off, rain and wind. While several studies have been conducted on the fate of Cry1Ab protein in terrestrial ecosystems, little is known of the release rates of Cry1Ab proteins from maize plant tissues that end up in aquatic ecosystems. In this study, leaves of Bt-maize and its isoline were submerged in containers filled with deionised or borehole water for a period of 16 days, and kept at 3 different temperatures (10±1, 21±1 and 30±1°C). Samples were collected at 1, 2, 4, 8, 16, 24, 48, 96, 192 and 384 h post submersion and analysed for Cry protein content using enzyme-linked immunosorbent assay (ELISA). The release of Cry protein from submerged maize leaves was influenced by temperature, and duration of immersion. An increase in Cry protein levels in the water was observed from the first hour onwards in both water types until the end of the experiment. The highest concentration of Cry protein was found at 30°C. This study showed that temperature and time period influence the release rate of Cry proteins from dried leaf matter into the aquatic environment.Keywords: aquatic ecosystem, arthropods, GM crops, environment, risk assessmen

The role of effect-based methods to address water quality monitoring in South Africa : a developing country’s struggle

Water is an important resource, and it is a worldwide struggle to provide water of good quality to the whole population. Despite good governing laws and guidelines set in place to help protect the water resources and ensure it is of good quality for various consumers, the water quality in South Africa is worsening due to lack of management. The deteriorating infrastructure is becoming progressively worse, due to corruption and insufficient funds. The ever-increasing number of toxicants, as well as the identification of emerging chemicals of concern, are also challenges South Africa is facing. Chemical analysis cannot determine the total biological effect of a mixture of chemical compounds, but this shortcoming can be addressed by adding effect-based methods (EBMs) to water quality monitoring programmes. In this paper, the current status of water quality monitoring in South Africa is discussed, as well as the capacity of the country to add EBMs to its water quality monitoring programmes to protect and improve human and animal life.The National Research Foundation and the Water Research Commission of South Africa.https://link.springer.com/journal/11356hj2023Urolog

Experience in South Africa of combining bioanalysis and instrumental analysis of PCDD/Fs

We outline the experiences and the challenges of optimizing two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GCxGC-TOF-MS) in conjunction with the H4IIE-luc bioassay for analyzing polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in the South African context. Investigating such alternative analytical methods can assist countries with developing economies to meet their obligations under the Stockholm Convention.Water Research Commission (WRC) of South Africa (K5/1561) and the South African/Norwegian Bilateral Agreement administered by the National Research Foundations (NRF) of South Africa and the Research Council of Norway (UID 64489).The authors also acknowledge support from a Discovery Grant from the National Science and Engineering Research Council of Canada (Project # 326415-07) and an instrumentation grant from the Canada Foundation for Infrastructure. Prof. Giesy was supported by the program of 2012 "High Level Foreign Experts" (#GDW20123200120) funded by the State Administration of Foreign Experts Affairs,the P.R. China to Nanjing University and the Einstein Professor Program of the Chinese Academy of Sciences. He was also supported by the Canada Research Chair program, an at large Chair Professorship at the Department of Biology and Chemistry and State Key Laboratory in Marine Pollution, City University of Hong Kong.http://www.elsevier.com/locate/trachb201

Marine Pyrrolocarbazoles and Analogues: Synthesis and Kinase Inhibition

Granulatimide and isogranulatimide are alkaloids obtained from marine sources which have been shown to inhibit cell-cycle G2-checkpoint, targeting more particularly checkpoint 1 kinase (Chk1). At a structural level, they possess a characteristic pyrrolocarbazole framework also shared by the well-known rebeccamycin and staurosporine microbial metabolites which have been described to inhibit topoisomerase I and diverse kinases, respectively. This review reports precisely on the synthesis and kinase inhibitory activities of pyrrolocarbazole-based analogues of granulatimide

Gesondheidassessering van visgemeenskappe blootgestel aan varkplaasuitvloeisel in die Vaalrivier, Suid-Afrika

<div style="font-size: 12px; font-family: serif; left: 227.349px; top: 323.055px; transform: scale(1.10776, 1); transform-origin: 0% 0% 0px;" dir="ltr">Die studie evalueer die moontlike effekte wat vrygestelde onbehandelde afloopsel van ‘n</div><div style="font-size: 12px; font-family: serif; left: 227.349px; top: 339.055px; transform: scale(1.11849, 1); transform-origin: 0% 0% 0px;" dir="ltr">varkboerdery op die walle van die Vaalrivier op die algehele gesondheid van visgemeenskappe stroom-af van die besoedelingspunt kan hê.</div