Some aspects on the reproductive cycle of European conger eel, Conger conger (Linnaeus, 1758) (Osteichthyes, Anguilliformes, Congridae) captured from Western Algerian coasts: a histological description of spermatogenesis

The aim of this work was to study the annual reproductive cycle of European conger eel (Conger conger,Linnaeus, 1758) through analysis and description of spermatogenesis. A sample of 168 males was capturedbetween September 2008 and August 2009 from the Western coast of Algeria, from Béni Saf. Fish length andweight varied between 26.20-112 cm and 0.45-3.44 kg, respectively.Condition factors (K), gonadosomatic index (G.S.I.) and hepatosomatic index (H.S.I.) were calculatedmonthly. Factor K reached the minimum in August/September (0.10%) corresponding to reproductive periodand a maximum in January (0.18%). Although G.S.I. values revealed to be statistically not significant, therewere two peaks for G.S.I., the first in March, denoting the beginning of spermatogenesis, and the second inAugust/September, indicating the reproduction period. H.S.I. reached a peak in December (1.90%), then thevalue decreased to a minimum in April.Histological analysis of testis allowed us to distinguish 5 stages summarized as follows: Stage 1:Spermatogonia A; Stage 2: Spermatogonia B; Stage 3: Spermatocytes and spermatids; Stage 4: Spermatocytes,spermatids and spermatozoa (cytodifferentiation of spermatids into spermatozoa); Stage 5: Spermatozoa(spermiogenesis or cytodifferentiation of spermatids into spermatozoa)

Dynamics of total body fatty acids during early ontogeny of pikeperch (Sander lucioperca) larvae

The fatty acid composition of pikeperch (Sander lucioperca) was determined according to their physiological status, during starvation (10 days) and feeding (28 days). In starved larvae, polyunsaturated, monounsaturated and saturated fatty acids were utilized as metabolic substrates until day 9. At day 10, all fatty acid levels remained stable or, at least, increased in larval body. Among fatty acids, docosahexaenoic acid 22:6 n-3 was used preferentially (20.3% from total fatty acids utilized) followed by palmitoleic acid 16:1 n-7 (13.9%) and then by oleic 18:1 n-9 (12.3%), linoleic 18:2 n-6 (10.1%), linolenic 18:3 n-3 (9.7%) and eicosapentaenoic 20:5 n-3 (9.1%) acids. On the other hand, arachidonic acid 20:4 n-6 was utilized very lowly (0.3%). In fed larvae, no utilization of body fatty acids was observed during the experiment. It seems that energy requirements (and others) of fed larvae were satisfied by feed

Study of reproductive aspects of <em>Trachurus trachurus</em> (Linnaeus, 1758) from western coast of Algeria

2469-2476In the present work, the reproductive study of the fish species Trachurus trachurus (Linnaeus, 1758) in Algeria, was investigated which is important for fishery resources and conservation management. 1495 samples were collected from Oran Bay (Western coast of Algeria) between July 2010 and June 2011. This paper provides values of sizes at first sexual maturity (L50) that were estimated for males at 18.42 cm and females 18.28 cm, respectively. The spawning period for the population extends from January to May and the spawning peak occurs from January to March. However, the factor of condition (K) increased in summer during the sexual resting phase. This factor is weak in winter during the period of reproduction. Regarding the sex ratio, there was no significant difference in the number of males and females

Physicochemical analysis of cellulose from microalgae Nannochloropsis gaditana

Nannochloropsis gaditana is a microalgae belonging to the class of Eustigmatophyceae. This particular microalga is the most studied species. For its richness in lipids, it is used for the biodiesel production. The aim of this work is to advance another important metabolite which is cellulose. This represents 25% of the dry weight of the N. gaditana. A low concentration of NaOH (2%) and sodium hypochlorite (6%) allowed the obtainment of relatively pure cellulose analyzed by Fourier transform infrared (FT-IR) and XRay Diffraction (XRD). The progress of the microalgae mass production could help in the substitution of the cellulose of microalgae for the vegetal cellulose, as seen in the simple technical extraction, the yield and the procurement of uncontaminated molecule with lignin. This substitution will contribute in protecting the environment.Keywords: Cellulose, Nannochloropsis gaditana, procedure extraction, structural characterizatio

Monitoring of Biogenic Amines in Tilapia Flesh (<i>Oreochromis niloticus</i>) by a Simple and Rapid High-Performance Thin-Layer Chromatography Method

peer reviewe

Extreme and Heterogeneous Conditions of the Desert Wetland Chott Ech Chergui (Algeria) Allow Isolating Halophilic, Alkalophilic and Thermophilic Bacteria

International audienceWetlands concentrate biodiversity, particularly in arid regions. Chott Ech Chergui (Algeria), one of the biggest wetlands of the north African desert, presents extreme temperatures and salinity conditions. We initiated a physico-chemical and microbiological survey at seven sites encompassing various conditions (salt lakes, freshwater lakes and hot springs), through a one-year monthly sampling campaign. Four sites under the influence of the spring showed little temporal physio-chemical variation. Three sites displayed higher variation and the aridity level, high from late spring until autumn, was a strong predictor of water chemistry. We evidenced extremophile bacteria. Among 320 bacterial isolates tested for thermo-, acido- and alcalino- tolerance, 39, affiliated to Firmicutes and Proteobacteria, were successfully maintained and underwent physiological, biochemical and molecular characterizations. Thermotolerance was recorded up to 100 °C for a water isolate affiliated to Geobacillus stearothermophilus. Halotolerance was recorded up to 30% NaCl (w:v) for soil isolates affiliated to Salinicola zeshunii, Chromohalobacter beijerinckii and Virgibacillus halodenitrificans. Acido- and alcalo- tolerance were recorded for a pH range from 5 to 11 for several soil and water isolates affiliated to Exiguobacterium, Bacillus, Salinicola and Chromohalobacter genus. Our results comfort the interest of studying extremophile diversity in wetlands of the highly arid Sahara region