Foraging behaviour of Apis mellifera adansonii and its impact on pollination, fruit and seed yields of Citrullus lanatus at Nkolbisson (Yaoundé, Cameroon)

Honeybee (Apis mellifera adansonii Latreille (Hymenoptera: Apidae)) foraging activity was observed to evaluate its impact on pollination, fruit and seed yields of Citrullus lanatus (Thunb) Mansf (Cucurbitaceae) in the area of Yaoundé (Cameroon). Two lots of 775 female flowers were marked according to the presence or the absence of a protection for insect visits. The honey bees’ activity, the fruit set, the number of seeds per fruit were recorded. A. m. adansonii primarily foraged for nectar on C. lanatus throughout the whole blooming period of each plant and pollen collection was low. The mean maximum number of workers foraging at the same time was 331 ± 173 (n= 41) per 1000 flowers. The mean foraging speed was 10.20 ± 2.75 (n = 154) flowers per minute. The fruit set and the number of seeds per fruit of unprotected female flowers were significantly higher than those of female flowers protected from insects. A. m. adansonii pollination contributed 70.14% to the fruit set and seed yields. The conservation of A. m. adansonii colonies near C. lanatus population must be encouraged.Key words: Citrullus lanatus, Apis mellifera adansonii, pollination, yields, Cameroon.L’activité de butinage d’Apis mellifera adansonii Latreille (Hymenoptera : Apidae) a été étudiée afin d’évaluer son impact sur la pollinisation, les rendements fruitiers et grainiers de Citrullus lanatus (Thunb) Mansf (Cucurbitaceae) à Yaoundé (Cameroun). Deux lots ont été déterminés par le marquage de 775 fleurs femelles différant selon la présence ou l’absence de protection vis-à-vis des visites d’insectes. Le rythme saisonnier d’activité des abeilles domestiques, le taux de fructification des fleurs femelles et le nombre de graines par fruit ont été évalués. A. m. adansonii butinait les fleurs de C. lanatus tout au long de la période de floraison de chaque plante. Les butineuses prélevaient intensément le nectar pendant que la collecte du pollen était réduite. Le plus grand nombre d’ouvrières butinant simultanément était de 331 ± 173 (n = 41)par 1000 fleurs. La vitesse moyenne de butinage était de 10.20 ± 2.75 (n = 154) fleurs par minute. Le taux de fructification et le nombre moyen de graines matures par fruit des fleurs non protégées de l’activité des insectes étaient significativement élevés que ceux des fleurs femelles protégées. La contribution d’A. m. adansonii sur les rendements fruitiers et grainiers de C. lanatus était de 70.14% grâce à l’action pollinisatrice des ouvrières. La conservation des colonies d’A. m. adansonii à côté des populations de C. lanatus en fleurs doit être encouragée.Mots clés: Citrullus lanatus, Apis mellifera adansonii, pollinisation, rendements, Camerou

DC Priming by M. vaccae Inhibits Th2 Responses in Contrast to Specific TLR2 Priming and Is Associated with Selective Activation of the CREB Pathway

The environmental mycobacterium, M. vaccae has been used in mouse models to support the contemporary hygiene hypothesis that non-pathogenic microorganisms reduce allergy associated T helper (Th)2 responses and inflammatory diseases by augmenting regulatory T cells. However, data for human models and possible mechanisms are limited. We tested the effect of innate immune interactions between human DC and M. vaccae on DC-dependent T cell responses. M. vaccae activation of DC via Toll like receptor (TLR)2 was compared to a specific TLR2 ligand (Pam(3)CSK4) and alternative stimulation with a TLR4 ligand (LPS). M. vaccae induced DC dependent inhibition of Th2 responses, in contrast to Pam(3)CSK4, which had the opposite effect and LPS, which had no polarizing effect. DC maturation, gene expression and cytokine production, in response to each stimulus did not correlate with the specific functional effects. Comparable DC transcriptional responses to M. vaccae and Pam(3)CSK4 suggested that TLR2 mediated transcriptional regulation was not sufficient for inhibition of Th2 responses. Transcription factor enrichment analysis and assessment of signaling events, implicated a role for selective early activation of the CREB pathway by M. vaccae. Further study of the CREB pathway may provide novel insight into the molecular mechanisms of DC-dependent T cell polarization

Circadian rhythms in Mexican blind cavefish Astyanax mexicanus in the lab and in the field

Biological clocks have evolved as an adaptation to life on a rhythmic planet, synchronising physiological processes to the environmental light–dark cycle. Here we examine circadian clock function in Mexican blind cavefish Astyanax mexicanus and its surface counterpart. In the lab, adult surface fish show robust circadian rhythms in per1, which are retained in cave populations, but with substantial alterations. These changes may be due to increased levels of light-inducible genes in cavefish, including clock repressor per2. From a molecular standpoint, cavefish appear as if they experience ‘constant light’ rather than perpetual darkness. Micos River samples show similar per1 oscillations to those in the lab. However, data from Chica Cave shows complete repression of clock function, while expression of several light-responsive genes is raised, including DNA repair genes. We propose that altered expression of light-inducible genes provides a selective advantage to cavefish at the expense of a damped circadian oscillator

Direct cell reprogramming is a stochastic process amenable to acceleration

Direct reprogramming of somatic cells into induced pluripotent stem cells (iPSCs) can be achieved by overexpression of Oct4, Sox2, Klf4 and c-Myc transcription factors, but only a minority of donor somatic cells can be reprogrammed to pluripotency. Here we demonstrate that reprogramming is a continuous stochastic process where almost all donor cells eventually give rise to iPSCs upon continued growth and transcription factor expression. Additional inhibition the p53/p21 pathway or overexpression of Lin28 increased the cell division rate and resulted in an accelerated kinetics of iPSC formation that was directly proportional to the increase in cell proliferation. In contrast, Nanog overexpression accelerated reprogramming in a predominantly cell division rate independent manner. Quantitative analyses define distinct cell division rate dependent and independent modes for accelerating the stochastic course of reprogramming, and suggest that the number of cell divisions is a key parameter driving epigenetic reprogramming to pluripotency

Nutritional Regulation of Mammary miRNome: Implications for Human Studies

Mammary gland is the organ of milk component synthesis that provides the nutrients for growth and development of the mammalian neonate. In addition to macronutrients like proteins, carbohydrates, and lipids known for their roles in providing substrate and energy, a new class of components has been identified notably microRNA that have signaling roles regulating a large set of biological processes. MicroRNAs, short noncoding RNAs, have been reported to act on the mammary tissues, influencing mammary development and milk component biosynthesis, and evidence is now assembling that they also signal to the infant. The expression profile of these miRNAs can be under nutritional regulation. Their presence in milk and their relative persistency through industrial treatment open new way of investigations to use them as biomarkers of animal health, as well as to evaluate their effects on the health of those consuming them. Due to the role of miRNAs on human health and diseases, their transfer from milk or milk products to infants and adults is being actively researched, though their bioavailability is not known. Research is defining their distribution in the different fractions of milk (such as cells, exosomes, fat globule, or skim milk). Indeed, the unique packaging of miRNAs could be crucial for their action through the intestinal tract. The value of milk miRNAs to diverse aspects of human health is now an emerging field of scienc