RAINFALL VARIABILITY AND DROUGHT INFERENCE IN SUDANO-SAHELIAN REGION OF NIGERIA

Rainfall variability in Sudano-Sahelian regions of Nigeria (SSRN) over the 20th century and its poten-        tial links to the Sahelian drought have been examined using daily rainfall series from seven synoptic        stations in SSRN. Using the 30 year climate interval (i.e., 1940-1970 and 1970-2000), the percentage        changes in mean monthly rainfall depth and number of rain days, ranges between 4 and 33% for the        core season and between 3 and 70% in the marginal periods. The standardized rainfall index (SRI)        and normalized rain day index (NRI), two statistical descriptors, are defined and used in this study to        highlight the variability in rainfall and infer drought occurrence in SSRN. Both indices reveal that the        temporal variability in the amount and distribution of rainfall and number of rain days observed within        the region have to a large extent contributed to the 1973 and 1984 drought occurrences in the region.        Similarly, the relatively low NRI values observed within the region for the recent years may also be an        indication that the drought conditions since the early 1970s might be reoccurring.&nbsp

Water resources potentials of Hadejia River Sub-catchment of Komadugu Yobe River Basin in Nigeria

A. Sobowale1, J. K. Adewumi1, J. A. Otun2, D. B. Adie2(1. Department of Agricultural Engineering, University of Agriculture, Abeokuta. Nigeria;2. Department of Water Resources Engineering, Ahmadu Bello University, Zaria. Nigeria) Abstract: A water audit of the Hadejia river sub-catchment of Komadugu Yobe River basin of Nigeria (KYB) has been carried out.  The available water in this sub-catchment was compared with existing and potential water demands; results show that about 2,619 million cubic meters (MCM) of surface water is available annually upstream of Wudil (HS 1), 658 MCM is available between Wudil and Hadejia (HS 2), while 905 MCM is available between Hadejia and Gashua (HS 3).  Analysis of direct ground water recharge revealed that 86 mm, 94 mm and 8 mm of water is recharged to groundwater annually in the three hydrological sections HS 1, HS 2 and HS 3 respectively.  It is obvious that the least ground water recharge takes place in the Hadejia - Nguru Wetlands.  Presently, no water stress was observed in the sub catchment, the potential water balance of the area shows that about 75% of the available water between Wudil and Hadejia section (HS 2) would be used up by 2010 going by the current development rate.  Projections show that the water use rate will reach 100% by 2018.  At this time, water scarcity will be experienced in this sub-catchment if urgent steps are not taken to address the situation.  Integrated water resources management (IWRM) strategies were advanced for the sub-catchment in order to avert the crisis.Keywords: water resources potentials, water budget, river catchment system, soil moisture deficit, runoff, recharge, Nigeria Citation: Sobowale A, J K Adewumi, J A Otun, and D B Adie.  Water resources potentials of Hadejia River Sub - catchment of Komadugu Yobe River Basin in Nigeria.  Agric Eng Int: CIGR Journal, 2010, 12(2): 1-6.  &nbsp

Ligand-directed covalent labelling of a GPCR with a fluorescent tag in live cells

© 2020, The Author(s). To study the localisation of G protein-coupled receptors (GPCR) in their native cellular environment requires their visualisation through fluorescent labelling. To overcome the requirement for genetic modification of the receptor or the limitations of dissociable fluorescent ligands, here we describe rational design of a compound that covalently and selectively labels a GPCR in living cells with a fluorescent moiety. We designed a fluorescent antagonist, in which the linker incorporated between pharmacophore (ZM241385) and fluorophore (sulfo-cyanine5) is able to facilitate covalent linking of the fluorophore to the adenosine A2A receptor. We pharmacologically and biochemically demonstrate irreversible fluorescent labelling without impeding access to the orthosteric binding site and demonstrate its use in endogenously expressing systems. This offers a non-invasive and selective approach to study function and localisation of native GPCRs

Decidual natural killer cell interactions with trophoblasts are impaired in pregnancies at increased risk of preeclampsia.

Transformation of the uterine spiral arteries (SAs) during pregnancy is critical to support the developing fetus, and is impaired in some pregnancy disorders, including preeclampsia. Decidual natural killer (dNK) cells play a role in SA remodeling, although their interactions with fetal trophoblast remain unclear. A uterine artery Doppler resistance index (RI) in the first trimester of pregnancy can be used as a proxy measure of the extent of SA remodeling; we have used this technique to characterize dNK cells from pregnancies with normal (normal RI) and impaired (high RI) SA remodeling, which display least and highest risk of developing preeclampsia, respectively. We examined the impact of dNK cell secreted factors on trophoblast motility, chemoattraction, and signaling pathways to determine the contribution of dNK cells to SA transformation. We demonstrated that the chemoattraction of the trophoblast by dNK cells is impaired in pregnancies with high RI, as is the ability to induce trophoblast outgrowth from placental villous explants. These processes are dependent on activation of the extracellular signal-regulated kinase 1/2 and phosphatidylinositol 3-kinase-Akt signaling pathways, which were altered in trophoblasts incubated with secreted factors from dNK cells from high RI pregnancies. Therefore, by characterizing pregnancies using uterine artery Doppler RI before dNK cell isolation, we have identified that impaired dNK-trophoblast interactions may lead to poor placentation. These findings have implications for pregnancy pathological conditions, such as preeclampsia

Analysis of dry spells and its application to crop planning in The Sudano-Sahelian region of Nigeria

This study analyzed the sequences of dry and wet spells occurrence using the 1918-2004 rainfall data from the Sudano-Sahelian region in Nigeria (SSRN). It evaluates and uses the distribution and probabilities of the intra-season dry spell to describe how effective crop planning can be achieved in the midst of prevailing dry spells in SSRN. The approach adopted also involves the use of some other empirical computations to determine the risk level and percentage frequencies of dry spells for successive days after sowing (DAS) a crop. The results of the probabilities of maximum dry-spell length exceeding 7 to 15 days over the next 30-days helped to assess if the break of a dry spell due to rain has a significant impact on the subsequent spell length. The maximum dry spell length at five probability levels (risk levels) for different DAS and rainfall thresholds as well as the computation of the probable length of growing season provides estimates of appropriate time of sowing, type of crop to grow, and the cropping pattern to be adapted in the midst of the prevailing dry spell conditions in SSRN

Occurrence and Levels of Acetonitriles as Emerging Disinfection By-products in a Community Drinking Water Supply

Drinking water from Ahmadu Bello University (ABU) Zaria water treatment plant was sampled and analysed for haloacetontriles (HANs) disinfection by products (DBPs) between 2008 and 2010. This was to determine the degree of wholesomeness of the drinking water supplied to the university community. On analyses, samples were found to positively contain dichloroacetonitriles, dibromoacetonitrile, and bromochloroacetonitrile among the commonly known haloacetronitriles in drinking water. They were detected at chlorination stage and sometimes in the house level water samples. Bromochloroacetonitrile mean concentration of 1.3927E-02±6.1033E-06 mg/L was detected in the chlorinated samples and was lost in samples from the distribution system most probably due to its hydrolysis in water. On the other hand, mean levels of dibromoacetonitrile and dichloroacetonitrile were observed to increase from 1.0605E-02±3.3349E-05 mg/L of and 1.36431E-03±1.4647E-06 mg/L, respectively, in the chlorinated sample to 2.4731E-02±5.2273E-04 mg/L and 2.2190E-03±1.8910E-06 mg/L in the house level water samples, respectively. This trend in mean concentration could be traceable to influence of increased acidity (decreased pH) and total organic carbon. These showed that the treated drinking water supplied to the university community was within the WHO, 2004 provisional guideline recommendations that individual haloacetonitrile could have concentration exceeding 0.01 mg/L. However, the distributed water contained higher levels than the generally assumed concentration of 0.002 mg/L (WHO, 2004). This has implication for increased glutathione (GSH) lipid peroxidation and covalent bond associated with haloacetonitrile related radioactivity to gut tissues resulting from scavenging reactive oxygen (ROS). Although not among the regulated DBPs, HANs presence in distributed drinking water could open up a new frontier of DBPs health risks. Hence, their levels need be monitored, their effects determined and adequately documented for regulation. Thus, would wholesome and potable drinking water (a human right) be guaranteed to the students, staff and their dependant family members of the ABU community

Ca2+ stores in smooth muscle cells: Ca2+ buffering and coupling to AVP-evoked inositol phosphate synthesis

Cytosolic Ca2+ concentrations ([Ca2+]cyt) and [3H]inositol phosphates ([3H]InsP) were correlated while decreasing the Ca2+ content of sarcoplasmic reticulum (SR) stores in cultured A7r5 cells at rest and after activation with 8-arginine vasopressin (AVP). Decreasing Ca2+ influx by reducing extracellular Ca2+ or by treatment with verapamil had no effect on resting [Ca2+]cyt but significantly inhibited the AVP-evoked Ca2+ transients (delta Ca2+). Neither treatment affected basal [3H]InsP, but both treatments increased AVP-evoked synthesis of [3H]InsP. Likewise, basal [3H]InsP were unaffected by brief (10-30 s) exposures to thapsigargin (TG), while AVP-induced [3H]InsP synthesis was significantly augmented. Similar treatment with TG rapidly increased resting [Ca2+]cyt and decreased SR Ca2+ by 9-25% as manifested by decreased delta Ca2+. By contrast, ryanodine induced slow increases in [Ca2+]cyt that stabilized within 30 min; subsequent AVP-induced delta Ca2+ were attenuated by 50%. Ryanodine had no effect on either basal or stimulated [3H]InsP levels. Agents that elevate adenosine 3',5'-cyclic monophosphate (cAMP) such as caffeine, 8-bromo-cAMP, and forskolin inhibited AVP-evoked [3H]InsP formation. These observations provide further characterization of a communication pathway between the AVP-sensitive Ca2+ stores in the SR and the plasmalemmal enzyme system involved in the synthesis of inositol 1,4,5-trisphosphate. This pathway is manifested by an inverse relationship between the Ca2+ content of an AVP-sensitive, ryanodine-insensitive SR Ca2+ store and evoked [3H]InsP synthesis and may represent an important component in the tonic regulation of resting [Ca2+]cyt and vasoconstrictor- and hormone-evoked SR Ca2+ release

The responsiveness of isolated human hand vein endothelial cells in normal pregnancy and in pre-eclampsia

Human hand vein endothelial cells were isolated from blood obtained by traumatic venepuncture. Cells were identified as endothelial by staining with endothelium-specific antibodies. The subject groups studied were (i) non-pregnant, (ii) pregnant (mean, 35 weeks gestation) and (iii) pre-eclamptic women (mean, 36 weeks gestation).Fura-2 was used to measure agonist-induced responses in intracellular Ca2+ in single endothelial cells isolated and maintained in vitro. All of the cells examined responded to adenosine triphosphate (ATP) with a large transient increase in Ca2+ followed by a sustained plateau.The responses to ATP were significantly larger in the cells from pregnant women than in those from non-pregnant and pre-eclamptic women, but no other differences were observed. The amplitudes of the responses to ATP were (means ± s.e.m.) 0.56 ± 0.04, 1.42 ± 0.24 and 0.65 ± 0.09 fura-2 ratio units for cells from non-pregnant, pregnant and pre-eclamptic subjects, respectively.In cells isolated from non-pregnant subjects, the amplitude of the responses to carbachol, histamine and bradykinin were all smaller than those activated by ATP: 5.1, 13.9 and 4.4%, respectively. Not all cells responded to these agonists: 25% responded to carbachol, 70.5% responded to histamine and 12.5% responded to bradykinin. Sixty-five per cent of the cells from normotensive pregnant subjects responded to bradykinin compared with 25% in the non-pregnant and 13.9% in the pre-eclamptic subjects.These data suggest that there may be differences in the responsiveness of venous endothelial cells in pregnancy and that pre-eclamptic cells behave differently