Spatial distribution of saline water and possible sources of intrusion into a tropical freshwater lagoon and the transitional effects on the lacustrine ichthyofaunal diversity

The spatial distribution of saline water and possible sources of intrusion into Lekki lagoon and transitional effects on the lacustrine ichthyofaunal characteristics were studied during March, 2006 and February, 2008. The water quality analysis indicated that, salinity has drastically increased recently in the lagoon (0.007 to 4.70%). This study has identified three possible sources for saline water intrusion, beyond the seasonal input from the two adjacent lagoons (Lagos and Mahin), salt water intrusion by subsurface flow through the barrier beach from the ocean, and leaching of ions through lagoon bottom sediments. Eighty one fish species belonging to 40 families, 56 genera and 14 orders encountered were mostly freshwater, euryhaline and marine species adapted to life in the lagoon. The shell fish included the freshwater prawns Macrobrachium spp and the portunid crab Callinectes amnicola. This high number of fish species recorded from Lekki Lagoon in this study has confirmed the fact that this lagoon is a transition area between brackish water (Lagos Lagoon and Mahin Creek) and freshwater (Rivers Saga and Oshun).Key words: Spatial distribution, saline water, lacustrine, ichthyofaunal, diversity

An evaluation of Iken fishing strategy in tropical Lekki lagoon, Nigeria

This paper presents the results of the investigations of the fish aggregating device which served as fisheries enhancement techniques for the improvement of the productivity of the Lekki Lagoon between March 2006 and February 2008. The performance of the floating Island (Iken fishery) depends on the size and the thickness. Chrysichythys nigrodigitatus contributed 25.51, 23.42 and 25.19% of the total weight of fish from floating Island with water hyacinth, Vossia sp and Cyperus sp dominant plant respectively. Tilapia guineensis contributed 17.0, 21.55 and 23.18% for water hyacinth, Vossia sp and Cyperus sp as dominant plant respectively. The fishing with acoustic yielded the highest catch by weight (47.22%) followed by fishing without acoustics (33.33%) with the least recorded in the open lagoon (19.44%). Management measures to maintain optimal production from Iken fishery should include the use of luxuriant water hyacinth which will reduce deforestation and erosion of the mangrove belt. The community managed resource enhancement should evolve from the existing traditional practices to meet both economic and social objectives as a major management strategy.Key words: Fish shelter, fish aggregating devices, Iken fishery

Cast net design characteristics, catch composition and selectivity in tropical open lagoon

Cast net design characteristics, construction, operational techniques and selectivity in Lagos lagoon, Nigeria was examined between September and December 2005. Netting materials for cast netconstruction in Lagos lagoon were monofilament nylon, poly-ethylene (PE) and polyester (PES). The conventional ratio 1:2 of the number of meshes in the length of the apical panel to the second was notadopted by the fishermen. The cast net length was 1.77 m and net mouth area was 4.99 m2. Twenty-one fish species belonging to 19 families were caught during the study period. Sarotherodon melanotheron was numerically most abundant in Lagos lagoon. Numerically, more fish specimens were caught at night than daytime. The higher the effort (throw) the more the cast net catches. The condition factor (K) of fishes in the lagoon ranged between 0.27 and 3.0. The crustacean had the overall highest condition factor. A total of 1,501 specimens (30 kg) at N 4, 500 (USD 32.14) were caught for 11 trips (247 casts) for 38.7 h. The Catch Per Unit Effort (CPUE) (number of catch per cast) ranged between 0 and 6; the average number of cast per hour was 6. Cast net was not species specific. The smallest fish (S. melanotheron) had a burst speed of 51 cm per second while the largest (L. falcipinnis) had a maximum burst speed of 262 cm per second. Cast net was selective for shallow water species. Cast nets durability ranged from 3 months to 3 years depending on the netting material and the environment where it is operated

Comparative analysis of the proximate compositions of Tarpon atlanticus and Clarias gariepinus from culture systems in South -Western Nigeria

The comparative analysis of the proximate compositions of Tarpon atlanticus (megalops) and Clarias gariepinus (African catfish) collected from two culture systems (Pen and concrete pond) were examined. Parameters of proximate composition analysed were moisture, ash, protein, fibre, fat and carbohydrate from the head and tail region. Proximate composition comparison was also done with varioussizes of the two species of fish which are the juvenile, young adult and adult forms. The total length and weight of juvenile ranged from 24.5 - 26.5cm, 178.3 - 180g and 25.2 - 27.4cm, 177.6 -179.5g for T. atlanticus and C. gariepinus, respectively. For the young adult, the total length and weight ranged from 27.0 - 28.5cm, 212.0 - 220.1g and 26.9 - 29.4cm, 214.2 - 221.3g for T. atlanticus and C. gariepinus, respectively. For the adults, the total length and weight ranged from 40.20 - 42.10cm, 783 - 800g and 39.9 - 44.5cm, 785 - 805g for T. atlanticus and C. gariepinus, respectively. Analysis of variance (ANOVA) showed no significant difference (P<0.05) between the moisture content of T. atlanticus and C. gariepinus in the adult head although there was a significant difference (P<0.01) between the ash of T. atlanticus and C. gariepinus in the adult tail. There was no significant difference (P<0.05) between the protein of T. atlanticus and C. gariepinus in the young adult tail but there was a significant difference (p<0.05) between the fibre of T. atlanticus and C. gariepinus inthe juvenile tail. There was a significant difference (p<0.01) between the fat and oil of T. atlanticus and C. gariepinus. Ash content was highest in the adult head of T.atlanticus and lowest in the adult tail of C. gariepinus. Protein was at its highest in the young adult tail of C. gariepinus and lowest in the juvenile head of T. atlanticus. The low concentration of lipids in the muscles of these species could be due to poor storage mechanisms and the use of fat reserves during spawning activities. Generally the two species contain high protein content as found out in this study. The high tissue protein content may have resulted from high protein content of their diets. Thus, both fish species constitute a high source of protein and low fatty acids, as well as an ideal dietetic fish food for human consumption

The effect of government support on bureaucracy, COVID-19 resilience and export intensity: Evidence from North Africa.

The literature on the imperativeness of government support for firm survival since the onset of COVID-19 is vast, but scholars have scarcely considered the impact of such assistance on managers' time, nor the extent to which support measures induce resilience and export activity. Accordingly, this study assesses the impact of government support on (1) bureaucracy and (2) resilience using data from 535 Moroccan SMEs. It further evaluates the influence of resilience on direct versus indirect exports, and espouses the institutional voids, resource-based and strategy-creation view to explain the associations through a contingency lens. The results demonstrate that (1) government support increases bureaucracy which, (2) surprisingly triggers and enhances resilience. Furthermore, (3) resilience has a positive impact on direct exports but (4) adversely affects indirect exports. Theoretically, the findings acquiesce extant calls for measurement specificity in export performance. Practically, stakeholders' attention is drawn to the value of managers' time well spent

Classification of microarray data using gene networks

BACKGROUND: Microarrays have become extremely useful for analysing genetic phenomena, but establishing a relation between microarray analysis results (typically a list of genes) and their biological significance is often difficult. Currently, the standard approach is to map a posteriori the results onto gene networks in order to elucidate the functions perturbed at the level of pathways. However, integrating a priori knowledge of the gene networks could help in the statistical analysis of gene expression data and in their biological interpretation. RESULTS: We propose a method to integrate a priori the knowledge of a gene network in the analysis of gene expression data. The approach is based on the spectral decomposition of gene expression profiles with respect to the eigenfunctions of the graph, resulting in an attenuation of the high-frequency components of the expression profiles with respect to the topology of the graph. We show how to derive unsupervised and supervised classification algorithms of expression profiles, resulting in classifiers with biological relevance. We illustrate the method with the analysis of a set of expression profiles from irradiated and non-irradiated yeast strains. CONCLUSION: Including a priori knowledge of a gene network for the analysis of gene expression data leads to good classification performance and improved interpretability of the results

Human immunodeficiency virus and AIDS and other important predictors of maternal mortality in Mulago Hospital Complex Kampala Uganda

BACKGROUND: Women with severe maternal morbidity are at high risk of dying. Quality and prompt management and sometimes luck have been suggested to reduce on the risk of dying. The objective of the study was to identify the direct and indirect causes of severe maternal morbidity, predictors of progression from severe maternal morbidity to maternal mortality in Mulago hospital, Kampala, Uganda. METHODS: This was a longitudinal follow up study at the Mulago hospital's Department of Obstetrics and Gynaecology. Participants were 499 with severe maternal morbidity admitted in Mulago hospital between 15th November 2001 and 30th November 2002 were identified, recruited and followed up until discharge or death. Potential prognostic factors were HIV status and CD4 cell counts, socio demographic characteristics, medical and gynaecological history, past and present obstetric history and intra- partum and postnatal care. RESULTS: Severe pre eclampsia/eclampsia, obstructed labour and ruptured uterus, severe post partum haemorrhage, severe abruptio and placenta praevia, puerperal sepsis, post abortal sepsis and severe anaemia were the causes for the hospitalization of 499 mothers. The mortality incidence rate was 8% (n = 39), maternal mortality ratio of 7815/100,000 live births and the ratio of severe maternal morbidity to mortality was 12.8:1.The independent predictors of maternal mortality were HIV/AIDS (OR 5.1 95% CI 2-12.8), non attendance of antenatal care (OR 4.0, 95% CI 1.3-9.2), non use of oxytocics (OR 4.0, 95% CI 1.7-9.7), lack of essential drugs (OR 3.6, 95% CI 1.1-11.3) and non availability of blood for transfusion (OR 53.7, 95% CI (15.7-183.9) and delivery of amale baby (OR 4.0, 95% CI 1.6-10.1). CONCLUSION: The predictors of progression from severe maternal morbidity to mortality were: residing far from hospital, low socio economic status, non attendance of antenatal care, poor intrapartum care, and HIV/AIDS.There is need to improve on the referral system, economic empowerment of women and to offer comprehensive emergency obstetric care so as to reduce the maternal morbidity and mortality in our community

Increased Mast Cell Density and Airway Responses to Allergic and Non-Allergic Stimuli in a Sheep Model of Chronic Asthma

BACKGROUND: Increased mast cell (MC) density and changes in their distribution in airway tissues is thought to contribute significantly to the pathophysiology of asthma. However, the time sequence for these changes and how they impact small airway function in asthma is not fully understood. The aim of the current study was to characterise temporal changes in airway MC density and correlate these changes with functional airway responses in sheep chronically challenged with house dust mite (HDM) allergen. METHODOLOGY/PRINCIPAL FINDINGS: MC density was examined on lung tissue from four spatially separate lung segments of allergic sheep which received weekly challenges with HDM allergen for 0, 8, 16 or 24 weeks. Lung tissue was collected from each segment 7 days following the final challenge. The density of tryptase-positive and chymase-positive MCs (MC(T) and MC(TC) respectively) was assessed by morphometric analysis of airway sections immunohistochemically stained with antibodies against MC tryptase and chymase. MC(T) and MC(TC) density was increased in small bronchi following 24 weeks of HDM challenges compared with controls (P<0.05). The MC(TC)/MC(T) ratio was significantly increased in HDM challenged sheep compared to controls (P<0.05). MC(T) and MC(TC) density was inversely correlated with allergen-induced increases in peripheral airway resistance after 24 weeks of allergen exposure (P<0.05). MC(T) density was also negatively correlated with airway responsiveness after 24 challenges (P<0.01). CONCLUSIONS: MC(T) and MC(TC) density in the small airways correlates with better lung function in this sheep model of chronic asthma. Whether this finding indicates that under some conditions mast cells have protective activities in asthma, or that other explanations are to be considered requires further investigation

Anomalous Hypothalamic Responses to Humor in Cataplexy

Cataplexy is observed in a subset of patients with narcolepsy and affects approximately 1 in 2,000 persons. Cataplexy is most often triggered by strong emotions such as laughter, which can result in transient, yet debilitating, muscle atonia. The objective of this study was to examine the neural systems underlying humor processing in individuals with cataplexy.While undergoing functional Magnetic Resonance Imaging (fMRI), we showed ten narcolepsy-cataplexy patients and ten healthy controls humorous cartoons. In addition, we examined the brain activity of one subject while in a full-blown cataplectic attack. Behavioral results showed that participants with cataplexy rated significantly fewer humorous cartoons as funny compared to controls. Concurrent fMRI showed that patients, when compared to controls and in the absence of overt cataplexy symptoms, showed pronounced activity in the emotional network including the ventral striatum and hypothalamus while viewing humorous versus non-humorous cartoons. Increased activity was also observed in the right inferior frontal gyri--a core component of the inhibitory circuitry. In comparison, the one subject who experienced a cataplectic attack showed dramatic reductions in hypothalamic activity.These findings suggest an overdrive of the emotional circuitry and possible compensatory suppression by cortical inhibitory regions in cataplexy. Moreover, during cataplectic attacks, the hypothalamus is characterized by a marked decrease in activity similar to that observed during sleep. One possible explanation for these findings is an initial overdrive and compensatory shutdown of the hypothalamus resulting in full cataplectic symptoms