Investigation on the activities of yeasts in the post harvest spoilage of sweet potato(Ipomea batatas L.)

Postharvest losses due to the activities of indigenous microorganisms occur in many crops such as sweet potato (Ipomoea batatas) which result in heavy financial losses for farmers. Correct identification of the pathogen responsible for postharvest infection is central to adopting an appropriate control strategy. Samples of sweet potato tubers were purchased from the local market and stored at three temperatures: 13°C, 21°C and 29° for four weeks. Spoilage yeasts were isolated from the tuber samples. The isolates were characterized using yeast genomic DNA extraction, polymerase chain amplification of rRNA and sequence determination. The yeasts were identified on the basis of the 26S rDNA. Six yeast species were identified as Rhodotorula mucilaginosa, R. minuta, Pichiaguilliermondii, P. anomala, Sporobolomyces marcillae and Saccharomycopsis fibuligera. The results indicated that the D1 and D2 domains of the 5’ end of the 26S rDNA showed a high degree of interspecies sequence variation for the isolates. Two of the yeasts; P. anomala and R. minuta were selected for further investigations namely pathogenicity testing and assay for extracellular enzymes. Results of the pathogenicity tests showed that P. anomala and R. minuta were clearly able to infect the sweet potato tubers. The results of the enzyme assay revealed that P. anomala and R. minuta were able to secrete varying amounts of eight extracellular enzymes: cellulose, amylase, polygalacturonase, glucanase, xylanase, xylosidase, arabinofuranosidase and ferulic acid esterases. These enzymes have the capacity to degrade plant cell walls and possibly enhanced the pathogenicity of the yeasts. Key Words: Sweet-potato, yeast, Postharvest, Pathogenicity, Ipomoea batata

Influence of Tree Characters and Climate on Litter Characteristics in Daniellia oliveri (Rolfe) Hutch. & Dalziel

Litter production and decomposition rates have great importance inmaintaining the fertility of the soil. The study was carried out to determine the relationship tree characters (girth size, canopy radius, tree height, leaf area and number of primary branches), litter production and quality, and climatic variables among stands of Daniellia oliveri (Rolfe) Hutch. & Dalziel growing in University of Ilorin campus. Twelve trees of different girth sizes were selected and their physiognomic characters measured. Litter samples(leaves and twigs) were collected from the stands on monthly basis  (January to May) using 1 m2 traps. The collected litters were air-dried, ground and analysed for carbon, nitrogen, phosphorus, potassium, calcium and magnesium using standard methods. Rainfall and temperature data were collected during the sampling months. Girth size range was 0.32 – 0.67 m. Tree height range was 13.90 – 31.81 m. Primary branches range was 3 - 16, crown radii was 2.5 - 5.2 m and leaflet area between 24.62 cm2 and 90.90 cm2. Higher leaf litter was recorded in January and February, but twigs were more in the other months. Leaf and twig litters positively  correlated with girth size (r = 0.572 and 0.614 respectively), but the formeralso correlated with crown radii (r = 0.834). Carbon, calcium and  magnesium contents in leaves and twigs were lower in May compared to January, but reverse trend were observed for nitrogen and phosphorus. The number of rain (rainy days) negatively correlated with total monthly litter (r = -0.291). The study concluded that climatic conditions influence tree characters, which in turn affect litterfall and nutrient returns to the soil. ©JASE

In vitro effects of metals and pesticides on dehydrogenase activity in microbial community of cowpea (Vigna unguiculata) rhizoplane

Effects of heavy metals and pesticides on cowpea (Vigna unquiculata) rhizoplane microbial community  were assessed in vitro via dehydrogenase activity. The microbial community was exposed to various concentrations of heavy metals and pesticides in a nutrient broth-glucose-2,3,5-triphenyl chloride (TTC) medium. At 0.2 mM, iron and cadmium stimulated the dehydrogenase activity of the microbialcommunity. For all the metal ions, there was progressive inhibition with each successive increase in the concentration of metal ion, reaching near 100% at 0.6, 0.8, 1.2, 0.12 and 12 mM for cobalt, cadmium,iron, mercury and nickel, respectively. Between 0.2 and 0.4 mM, zinc sharply inhibited dehydrogenase activity and at concentration above 0.4 mm, inhibition of dehydrogenase activity became lesspronounced. The order of toxicity is Hg2+ > Co2+ > Cd2+ > Zn2+ > Fe2+ > Ni2+. The herbicides Cotrazine (Atrazine 80W) and Northrin®10EC stimulated dehydrogenase activity of the microbial community at 0.2% and inhibited it at higher concentrations. The median inhibitory concentrations (IC50s) of Cotrazine(Atrazine 80W) and Northrin®10EC were 0.552 ± 0.028 and 0.593 ± 0.051%, respectively. The dehydrogenase activity varied significantly (p < 0.05) with the type and concentrations of metals orpesticides. The result indicates that the heavy metals and pesticides are potentially toxic to V. unquiculata root surface microorganisms. In soil, this toxicity may affect nitrogen fixation processes and by extrapolation affect crop yield

Influence of Tree Characters and Climate on Litter Characteristics in Daniellia oliveri (Rolfe) Hutch. &amp; Dalziel

Litter production and decomposition rates have great importance in maintaining the fertility of the soil. The study was carried out to determine the relationship tree characters (girth size, canopy radius, tree height, leaf area and number of primary branches), litter production and quality, and climatic variables among stands of Daniellia oliveri (Rolfe) Hutch. &amp; Dalziel growing in University of Ilorin campus. Twelve trees of different girth sizes were selected and their physiognomic characters measured. Litter samples (leaves and twigs) were collected from the stands on monthly basis (January to May) using 1 m2 traps. The collected litters were air-dried, ground and analysed for carbon, nitrogen, phosphorus, potassium, calcium and magnesium using standard methods. Rainfall and temperature data were collected during the sampling months. Girth size range was 0.32 \u2013 0.67 m. Tree height range was 13.90 \u2013 31.81 m. Primary branches range was 3 - 16, crown radii was 2.5 - 5.2 m and leaflet area between 24.62 cm2 and 90.90 cm2. Higher leaf litter was recorded in January and February, but twigs were more in the other months. Leaf and twig litters positively correlated with girth size (r = 0.572 and 0.614 respectively), but the former also correlated with crown radii (r = 0.834). Carbon, calcium and magnesium contents in leaves and twigs were lower in May compared to January, but reverse trend were observed for nitrogen and phosphorus. The number of rain (rainy days) negatively correlated with total monthly litter (r = -0.291). The study concluded that climatic conditions influence tree characters, which in turn affect litterfall and nutrient returns to the soil

Knowledge of the Human Papilloma Virus vaccines, and opinions of Gynaecologists on its implementation in Nigeria

The objective of this study was to determine the knowledge and perception of Nigerian Obstetricians and Gynaecologists towards human papilloma virus vaccine use in Nigeria. A cross sectional study was conducted amongst participants that attended the 42nd Society of Gynaecology and Obstetrics of Nigeria. The findings revealed that 44.5% knew the correct HPV vaccine schedule. Regarding implementation in Nigeria, 87.4% suggested its incorporation into the national immunization program and about a third agreed that it should be a precondition for school enrolment. Regression analysis showed that senior residents were more likely to have adequate knowledge of the vaccine compared to junior residents (AOR 7.181 95% CI OR=1.792 – 28.782). We conclude that the knowledge of eligibility and schedule is poor. It is recommended that adequate information should be provided to this group of health workers because of their strategic position in its implementation in Nigeria (Afr J Reprod Health 2013); 17[2]:150-156).Keywords: Human papilloma Virus Vaccine, HPV, Knowledge, Perception, Nigeri

Long-Lasting Consequences of Neonatal Maternal Separation on Social Behaviors in Ovariectomized Female Mice

Maternal separation (MS) stress is known to induce long-lasting alterations in emotional and anxiety-related behaviors, but effects on social behaviors are not well defined. The present study examined MS effects on female social behaviors in the social investigation (SIT) and social preference (SPT) tests, in addition to non-social behaviors in the open-field (OFT) and light-dark transition (LDT) tests in C57BL/6J mice. All females were tested as ovariectomized to eliminate confounding effects of endogenous estrogen during behavioral testing. Daily MS (3 hr) from postnatal day 1 to 14 did not affect anxiety levels in LDT, but were elevated in OFT with modified behavioral responses to the novel environment. Furthermore, MS altered social investigative behaviors and preference patterns toward unfamiliar stimulus mice in SIT and short- and long-term SPT paradigms. In SIT, MS reduced social investigation duration and increased number of stretched approaches towards both female and male unfamiliar stimulus mice, suggesting increased social anxiety levels in MS females. Similarly, MS heightened levels of social anxiety during short-term SPT but no MS effect on social preference was found. On the other hand, MS females displayed a distinctive preference for female stimuli, unlike control females, when tested for long-term SPT over a prolonged period of 5 days. Evaluation of FosB expression in the paraventricular nucleus, medial and central amygdala following stimulus exposure demonstrated greater number of FosB immunopositive cells in all three brain regions in MS females compared to control females. These results suggest that MS females might differ in neuroendocrine responses toward unfamiliar female and male opponents, which may be associated with modifications in social behaviors found in the present study. Taken together, this study provides new evidence that early life stress modifies female social behaviors by highlighting alterations in behavioral responses to situations involving social as well as non-social novelty

The Evolution of Compact Binary Star Systems

We review the formation and evolution of compact binary stars consisting of white dwarfs (WDs), neutron stars (NSs), and black holes (BHs). Binary NSs and BHs are thought to be the primary astrophysical sources of gravitational waves (GWs) within the frequency band of ground-based detectors, while compact binaries of WDs are important sources of GWs at lower frequencies to be covered by space interferometers (LISA). Major uncertainties in the current understanding of properties of NSs and BHs most relevant to the GW studies are discussed, including the treatment of the natal kicks which compact stellar remnants acquire during the core collapse of massive stars and the common envelope phase of binary evolution. We discuss the coalescence rates of binary NSs and BHs and prospects for their detections, the formation and evolution of binary WDs and their observational manifestations. Special attention is given to AM CVn-stars -- compact binaries in which the Roche lobe is filled by another WD or a low-mass partially degenerate helium-star, as these stars are thought to be the best LISA verification binary GW sources.Comment: 105 pages, 18 figure

Frequent CEO Turnover and Firm Performance: The Resilience Effect of Workforce Diversity

© 2020, Springer Nature B.V. CEO turnover (or succession) is a critical event in an organization that influences organizational processes and performance. The objective of this study is to investigate whether workforce diversity (i.e., age, gender, and education-level diversity) might have a resilience effect on firm performance under the frequency of CEO turnover. Based on a sample of 409 Korean firms from 2010 to 2015, our results show that firms with more frequent CEO turnover have a lower firm performance. However, firms with more gender and education-level diversity could buffer the disruptive effect of frequent CEO turnover on firm performance to offer a benefit to the organization. Our theory and findings suggest that effectively managing diverse workforce can be a resilience factor in an uncertain organizational environment because diverse workforce has complementary skills and behaviors that can cope better with uncertainty and signals social inclusion of an organization, thus fostering a long-term exchange relationship. These findings contribute to the literature on CEO turnover (or succession) and diversity