The seasonal abundance of the phototrophic ciliate Mesodinium rubrum in Southampton Water, England

The abundance of the marine phototrophic planktonic ciliateMesodinium rubrum was monitored throughout an annual cycle attwo stations in the Southampton Water estuary. Seasonal changesin the concentration of nitrate, ammonia and phosphate weremonitored both at the inner estuary station (NW Netley) andouter estuary station (Calshot). Nutrient levels in the winterwere similar at both stations, and were diminished during sequentialdiatom blooms dominated initially by Sketetonema costatum andthen by Rhizosolenia dclicatula. Nitrate was reduced to a seasonalminimum in the outer estuary following these spring diatom blooms,but in the inner estuary was sustained >500 µg I^–1until the onset of the M.rubrum bloom. During the developmentof a visible red tide of M.rubrum in June/July at NW Netley,nutrient concentrations were considerably reduced. Cell numbersof M.rubrum varied between 2 and 3 cells ml^– during winterto >400 cells ml^–1 during the bloom at NW Netley, whereasat Calshot cell abundance did not increase above 25 cells ml^–1at any time of the year. At NW Netley, dense accumulations ofthe ciliate occurred over restricted depth intervals duringthe bloom and possible factors influencing the observed verticaldistribution of cells are considered. ¹Present address: Biology Department, Faculty of Science, AddisAbaba University, PO Box 1176, Addis Ababa, Ethiopia     

Historical range and movements of the Elephants in Babile Elephant Sanctuary,Ethiopia

A study on historical range and movement patterns of the African savannah elephants (Loxodonta africana africana) in Ethiopia was made from December 2004 to November 2008. Babile Elephant Sanctuary is one of the strongholds of elephants in the country, where it now supports approximately 27% of the elephant population in Ethiopia. Elephant movement routes and ranges were identified based on interviews of local people and by tracking the animals in the field. Elephants of the Sanctuary were categorized into two distinctive groups or clans based on their movement patterns and their associations to each other. Three major valleys, namely Gobele, Erer and Dakata, were crossed by elephants. Elephants in the population had an estimated annual range of 3014 km². Of this, 85.7% (2583 km²) was inside the Sanctuary and 14.3% (430 km²) outside but adjacent to the Sanctuary. Elephant use outside of the Sanctuary included three different areas: Upper Erer Valley (8 km²), Upper Gobele Valley (48 km²) and west of Gobele Valley (374 km²). The extent of range varied seasonally. During the wet season, elephant range was restricted to Erer Valley and its tributaries (1266 km² and a density of approximately 0.25 animal km^?2), or 42% smaller than the dry season range (1417 km², 0.23 elephant km^?2). Range use was smallest (332 km²) in October to November and from April to May. During the dry season, elephants were found in two distinctive groups, one using Gobele Valley and the other Erer Valley.     

Evaluation of growth and biomass production of Arthrospira (Spirulina) fusiformis in laboratory cultures using waters from the Ethiopian soda lakes Chitu and Shala

The cost of nutrient media is the major challenge for biomass production of Spirulina. Although much effort has been made to use enriched seawater for the cultivation of this microalga, little attention has been given to the potential of water of soda lakes. In this study, growth (μ, day^?1) and biomass production (B) of Arthrospira fusiformis cultivated using waters of the soda lakes Chitu and Shala with or without supplementation were evaluated. Comparable μ and B values were achieved in both Lake Chitu water-based media (CBM) and Lake Shala water-based media (SBM), with slightly higher values in the latter. Both CBM and SBM supplemented with the standard Spirulina medium (SM) by 25 % and 50 % supported considerably higher μ and B. The pH and salinity of the cultures showed significant variations (P?μ and B. The observed higher μ and B were probably associated with the reduction in pH and salinity of the supplemented media due to addition of bicarbonate–carbonates and dilution, and provision of the limiting nutrient nitrogen. The higher μ and B in SBM may have resulted from some of their aggregate chemical parameters, which were closer to those in the SM, and abundant PO₄-P. This seems to suggest that Lake Shala water is more conducive to Arthrospira. We contend that 25 % and 50 % supplemented Lake Shala water can be preferably used to produce Arthrospira biomass, thereby reducing the cost of nutrients by 75 % and 50 %, respectively.     

Rapid Evolution of Recombinant Saccharomyces cerevisiae for Xylose Fermentation through Formation of Extra-chromosomal Circular DNA

Circular DNA elements are involved in genome plasticity, particularly of tandem repeats. However, amplifications of DNA segments in Saccharomyces cerevisiae reported so far involve pre-existing repetitive sequences such as ribosomal DNA, Ty elements and Long Terminal Repeats (LTRs). Here, we report the generation of an eccDNA, (extrachromosomal circular DNA element) in a region without any repetitive sequences during an adaptive evolution experiment. We performed whole genome sequence comparison between an efficient D-xylose fermenting yeast strain developed by metabolic and evolutionary engineering, and its parent industrial strain. We found that the heterologous gene XylA that had been inserted close to an ARS sequence in the parent strain has been amplified about 9 fold in both alleles of the chromosomal locus of the evolved strain compared to its parent. Analysis of the amplification process during the adaptive evolution revealed formation of a XylA-carrying eccDNA, pXI2-6, followed by chromosomal integration in tandem arrays over the course of the evolutionary adaptation. Formation of the eccDNA occurred in the absence of any repetitive DNA elements, probably using a micro-homology sequence of 8 nucleotides flanking the amplified sequence. We isolated the pXI2-6 eccDNA from an intermediate strain of the evolutionary adaptation process, sequenced it completely and showed that it confers high xylose fermentation capacity when it is transferred to a new strain. In this way, we have provided clear evidence that gene amplification can occur through generation of eccDNA without the presence of flanking repetitive sequences and can serve as a rapid means of adaptation to selection pressure.     

Otolith age determination for adult tilapia, Oreochromis niloticus L. from Lake Awassa (Ethiopian Rift Valley) by interpreting biannuli and differentiating biannual recruitment

Age of mature Oreochromis niloticus in Lake Awassa, Ethiopia, was estimated by analysing optical macrozones (translucent and opaque) in sagittal otoliths from fish sampled over a 12-month period. Seasonal record on the type of macrozone at the edge of otoliths suggested that two translucent macrozones associated with biannuli were formed each year; one during January and February and another during June and July. Formation of translucent macrozones coincided with minimum water temperature, spawning associated loss in condition and presumably with reduction in the quantity and quality of the food consumed by the fish. Relative marginal increment analysis showed that biannulus formation may be completed in March and in August each year. A concurrent study has confirmed a biannual recruitment in O. niloticus in Lake Awassa, from which mid-February and mid-August were taken as median hatch-dates. A procedure to assign otolith age is described which considers median hatch-dates and uses the number of biannuli in otoliths without discriminating between fish from the two recruitment cohorts. We also show a procedure to discriminate between the two cohorts by using the number of biannuli, conditions on the edge of the otolith and time of capture to assign age for the two recruitment cohorts separately.     

Determinants of premature rupture of membrane in Southern Ethiopia, 2017: case control study design

Objective

To identify the determinants of term premature rupture of membrane in Southern Ethiopia public hospitals, 2017.

Results

Seventy-five cases and 223 controls women were enrolled for the study. Two hundred eighty-four (95.3%) participants were admitted at the gestational age of above 40, and the rest, 14 (4.7%), were admitted at 37–40 weeks of gestation. The current study identified wealth index and inter-birth interval as preventive predictors, but smoking and hypertension during pregnancy were identified as positive determinants of premature rupture of membrane. This finding is supported by multiple logistic regression analysis result of wealth index (AOR: 0.102, 95% CI [0.033, 0.315]), inter-birth interval (AOR: 0.251, 95% CI [0.129, 0 0.488]), smoking (AOR: 17.053, 95% CI [2.145, 135.6]), and hypertension (AOR: 8.92, 95% CI (1.91, 41.605]). The association between PROM and its determinants indicated that evidence-based interventions should be needed and designed to have very high wealth index, and optimal interbirth interval, and prevent smoking and hypertension during pregnancy to decrease PROM occurrence in the study settings. Hence, we recommended that integration of prevention mechanism of modifiable determinants to the obstetrics health care system will reduce premature ruptures of a membrane.

     

Micropropagation of Phytolacca dodecandra through shoot-tip and nodal cultures

A procedure for micropropagation of endod (Phytolacca dodecandra) is described. BA at 0.44 M produced 3.1 new shoots per expiant in six weeks using shoot tips. Nodal expiants, however, produced up to 4.7 shoots per explant on medium with 0.44 M BA and 0.27 M GA,. IBA at 0.49 M induced 90% rooting with minimal callus. Plantlets were successfully transferred to the greenhouse and some staminate clones produced flowers after six months.Abbreviations BA 6 benzylaminopurine - kinetin 6-furfurylaminopurine - 2iP N⁶-(2-isopentyl)adenine - IAA indole-3-acetic acid - NAA 1-naphthaleneacetic acid - GA₃ Gibberellic acid - IBA indole-3-butyric acid