Reproductive traits of the freshwater oyster Etheria elliptica (Bivalvia: Etheriidae) in the Pendjari River,Benin: implications for conservation

The African freshwater oyster Etheria elliptica, which is of great economic importance throughout the continent, is facing overharvesting in many fisheries in West Africa. Its reproductive traits (sex ratio, size at sexual maturity, oocyte diameter and fecundity) were studied at four stations located along the Pendjari River, northern Benin, in April 2013. Histological techniques were implemented to identify sex and gonad development stages. Oocyte sizes were measured based on the histological images and mean oocyte diameter was 38 µm. Fecundity, estimated by counting the developing eggs, averaged 106 724 eggs and increased significantly with shell size. The average sex ratio was approximately 1:1. Hermaphrodites were rare. Males reached sexual maturity at 57.6 mm dorsoventral height, earlier than females at 64.7 mm. The majority of the oyster specimens were in ripe-spawning stages, indicating that reproductive activities partly took place towards the end of the dry season. Both mature and immature individuals were subjected to harvesting at all the investigated fishing sites. The mean size of exploited oysters was 60.6 mm, lower than the size of females at maturity. Management strategies must enforce the minimum size of 65 mm required for harvesting, particularly in open access sites where juveniles are mostly harvested.     

Gene action for surrogate traits of water-use efficiency and harvest index in peanut (Arachis hypogaea)

Low peanut productivity in the semi‐arid tropics is attributed mainly to drought caused by low and erratic rainfall. Genetic improvement in water‐use efficiency (WUE) could potentially lead to improved yield under limited moisture availability. In peanut, WUE is correlated with SPAD chlorophyll meter reading (SCMR), specific leaf area (SLA), and carbon isotope discrimination (Δ¹³C). These traits can be used as surrogates for selecting for WUE. Partitioning of assimilates as measured by the harvest index (HI) has the greatest effect on pod yield. To improve these traits for tailoring peanut genotypes well matched for water‐limited conditions, a good knowledge of genetic systems controlling the expression of these traits is essential. This study was undertaken to work out the gene action for the surrogates of WUE and HI in a 6 × 6 full diallel mating design. Two of the studied surrogates (SCMR and Δ¹³C) for WUE were found to be under the influence of both additive and nonadditive gene effects with preponderance of the former. SLA and HI were controlled by genes that are mainly additive in nature. Selection for these traits can be effective in the early generations. Maternal effects observed for SLA and Δ¹³C are suggestive of the crucial role of selection of female parent in improvement of these traits. The parental lines, TMV 2 NLM (for SCMR, SLA and Δ¹³C) and ICGV 86031 (for SCMR and SLA), were found to be good general combiners each for more than one character. TAG 24 and Chico (for HI) and CSMG 84‐1 (for SLA) were the other good general combiners.     

CCK-8 antagonizes apomorphine-induced growth hormone secretion in normal subjects

Cholecystokinin octapeptide (CCK-8) (5 ug iv over 10 minutes) administered to normal men had no effect on basal growth hormone (GH) or prolactin secretion but significantly antagonized the GH response to the dopamine (DA) receptor agonist, apomorphine HCI (Apo) (0.5 mg sc), 30 (P less than 0.05) and 45 minutes (P less than 0.01) after Apo injection (n = 8). These results are compatible with an inhibitory effect of CCK-8 on certain DA mechanisms in the hypothalamic-pituitary axis. Whether CCK-8 affects DA function in other brain regions in man is unknown.     

Hepatic amoebiasis at high altitude

Latent amoebiasis is aggravated at high altitude. Protean manifestations are common. Fever is usually absent. Liver tenderness is not a feature and may have to be specially elicited. Leucocytosis is rare. Bowel symptoms inspite of presence of intestinal ulcerations are usually absent. Response to treatment with emetine or chloroquin is unsatisfactory and relapse rate is high. These points may interest mountaineers and other sojourners to high altitude.