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.     

The muscle flap in the treatment of chronic lower extremity osteomyelitis: results in patients over 5 years after treatment.

Preliminary reports have indicated that debridement of the bony sequestrum followed by muscle-flap coverage allows successful treatment of chronic osteomyelitis. To determine the long-term effectiveness of this procedure, 34 consecutive patients with chronic osteomyelitis of the distal lower extremity treated with debridement, a 10- to 14-day course of culture-specific antibiotics, and immediate muscle-flap coverage were evaluated. Patients were treated from 1979 through 1984, and long-term (greater than 5 years) follow-up was available for 27 (79 percent). Twenty-three (85 percent) of these patients underwent microvascular muscle transplantation (gracilis or latissimus dorsi), and four underwent local muscle flaps (gastrocnemius or soleus) for immediate wound coverage. Twenty-four patients (89 percent) healed and were without recurrence over long-term (greater than 5 years, mean 7.4 years) follow-up. Of the three with recurrence, two were cured (greater than 5 years follow-up) after additional muscle-flap procedures. Thus the overall success rate was 96 percent, with a minimum 5-year follow-up. Guidelines for muscle-flap selection and treatment techniques in current use are presented. Debridement and immediate muscle-flap coverage provide effective, single-stage treatment of chronic osteomyelitic wounds and allow antibiotics to be restricted to short-term use. Furthermore, muscle flaps covered with skin grafts provide durable coverage while allowing subsequent ancillary procedures (i.e., bone grafts) to be performed under the flaps.     

An infrared study of 2H-bond variation in myoglobin revealed by high pressure.

A high-pressure Fourier-transform infrared technique was used to probe the evolution of 2H bonds inside the helical segments of myoglobin in relation to p2H, Tris concentration in the medium and iron-ligand nature. The analysis was focused on changes in the conformation-sensitive amide-I' band, reflecting the peptide C = O group stretching vibrations coupled to the in-plane N-2H bending and C = N stretching modes. From data obtained under high pressure, the strength of 2H bonds, inside the alpha-helical segments of the protein at atmospheric pressure, is not simply a function of p2H and salt concentration. At low Tris concentration (50 mM), the strength of these 2H bonds increases with p2H, whereas for a higher Tris concentration (100 mM) this strength is lower at p2H 7 than at p2H 6.0 or 8.5. It is also observed that the azidometmyoglobin molecule exhibits tighter intrahelical interactions and lower sensitivity to pressure than aquametmyoglobin. Information is also presented regarding interhelical interactions in relation to the solvent.     

Clonal integration in Fragaria chiloensis differs between populations: ramets from grassland are selfish

In plants, only species with clonal growth are able to directly transfer resources between otherwise independent units of the same genetic individual. A simple conceptual model of plant performance as a function of internal resource supply and environmental resource availability suggests that resource sharing between ramets within clones is likely to be disadvantageous in uniform habitats and advantageous in patchy ones. It was therefore hypothesized that clones in populations from relatively uniform habitats will have been selected for low rates of resource sharing between ramets compared to clones in populations from patchier habitats. In coastal northern California, the clonal herb Fragaria chiloensis is common both in grasslands, where resources are relatively uniform, and on sand dunes, where resources are more patchy. It was predicted that clones from a grassland population of Fragaria would have “selfish” ramets with low rates of resource sharing compared to clones from an adjacent dune population. Ramets were subjected to contrasting light levels with and without connection between ramets. Patterns of biomass accumulation were consistent with the prediction. This appears to be the first report of genetically based variation in patterns of resource sharing in clonal plants. It supports the idea that these patterns are locally selected to increase plant performance in habitats with different patterns of resource availability. Received: 19 August 1998 / Accepted: 4 March 1999     

The effect of prostaglandin synthetase inhibitors on renal function: Studies in normal rats during sodium or water diuresis and in rats with chronic renal insufficiency

The effect of acute infusion of the prostaglandin synthetase inhibitors — meclofenamate or indomethacin — was examined in awake rats. Studies were performed in normal rats undergoing either sodium or water diuresis and in salt-replete rats with chronic renal insufficiency. Prostaglandin synthetase inhibitors had no effect on renal plasma flow, glomerular filtration rate or fractional excretion of sodium in any of the groups. Absolute urinary excretion rates for sodium and potassium decreased only in the normal, salt-replete rats. In contrast, prostaglandin synthetase inhibitors consistently decreased urinary flow and osmolar clearance under all experimental conditions studied. In the normal, salt-replete rats the fall in urine flow was preceded by an increase in urinary excretion of cyclic AMP. These results show that inhibitors of prostaglandin synthesis enhance the ability of the kidney to reabsorb water. This effect may be secondary to increased cyclic AMP generation and to increased urea recirculation resulting in higher urea accumulation in the renal medulla.