Cyclin A2 regulates erythrocyte morphology and numbers

Cyclin A2 is an essential gene for development and in haematopoietic stem cells and therefore its functions in definitive erythropoiesis have not been investigated. We have ablated cyclin A2 in committed erythroid progenitors in vivo using erythropoietin receptor promoter-driven Cre, which revealed its critical role in regulating erythrocyte morphology and numbers. Erythroid-specific cyclin A2 knockout mice are viable but displayed increased mean erythrocyte volume and reduced erythrocyte counts, as well as increased frequency of erythrocytes containing Howell-Jolly bodies. Erythroblasts lacking cyclin A2 displayed defective enucleation, resulting in reduced production of enucleated erythrocytes and increased frequencies of erythrocytes containing nuclear remnants. Deletion of the Cdk inhibitor p27^Kip1 but not Cdk2, ameliorated the erythroid defects resulting from deficiency of cyclin A2, confirming the critical role of cyclin A2/Cdk activity in erythroid development. Loss of cyclin A2 in bone marrow cells in semisolid culture prevented the formation of BFU-E but not CFU-E colonies, uncovering its essential role in BFU-E function. Our data unveils the critical functions of cyclin A2 in regulating mammalian erythropoiesis.     

New approach for determination of an optimum honeybee colony’s carrying capacity based on productivity and nectar secretion potential of bee forage species

The present study was carried out to determine an optimum honeybee colony’s carrying capacity of selected valleys dominated by Ziziphus spina-christi and Acacia tortilis in the Al-Baha region, Kingdom of Saudi Arabia. The study was conducted based on the assessment of the number of colonies kept, their productivities and the existing productive bee forage resources in the target valleys with its economic implication. In the existing beekeeping practice, the average number of managed honeybee colonies introduced per square kilometer was 530 and 317 during the flowering period of Z. spina-christi and A. tortilis, respectively. Furthermore, the overall ratios of productive bee forage plants to the number of honeybee colonies introduced were 0.55 and 11.12 to Ziziphus trees and A. tortilis shrubs respectively. In the existing situation the average honey production potential of 5.21 and 0.34 kg was recorded per Ziziphus and A. tortilis plants per flowering season, respectively. The present study, revealed that the number of honeybee colonies introduced in relation to the existing bee forage potential was extremely overcrowding which is beyond the carrying capacity of bee forage resources in selected valleys and it has been observed to affect the productivities and subsequent profitability of beekeeping. The study infers that, by keeping the optimum honeybee colony’s carrying capacity of valleys (88 traditional hives/km² or 54 Langstroth hives/km² in Ziziphus field and 72 traditional hives/km² or 44 Langstroth hives/km² in A. tortilis field), profitability of beekeeping can be boosted up to 130.39% and 207.98% during Z. spina-christi and A. tortilis, flowering seasons, respectively.     

The effects of ambient flow velocity,colony size,and upstream colonies on the feeding success of Bryozoa. II. Conopeum reticulum (Linnaeus), an encrusting species

The effects of ambient flow velocity, colony size, and the presence of an actively-feeding colony upstream on the feeding success of the encrusting bryozoan Conopeum reticulum (Linnaeus) were studied. Zooids from both large and small colonies showed a reduction in feeding as flow velocity increased, however, the reduction in feeding was less for zooids from large colonies except at very fast ambient flow velocities. The greater pumping capacity of large colonies may result in a relatively greater per zooid feeding success from moving water. The presence of an actively-feeding colony upstream was found to enhance the feeding of zooids on downstream colonies. Diversion of flowing water by actively-feeding colonies upstream may account for the observed enhancement of feeding by zooids on colonies downstream.The results from this study on an encrusting species are compared with results from a previous study on feeding from flow by an arborescent bryozoan, and the feeding performances of these two colony types are related to their respective flow microhabitats.     

Estimating the relative abundance of emperor penguins at inaccessible colonies using satellite imagery

Emperor penguin (Aptenodytes forsteri) populations are useful environmental indicators due to the bird’s extreme reliance on sea ice. We used remote sensing technology to estimate relative adult bird abundance at two inaccessible emperor penguin colonies in the Ross Sea, Antarctica. We performed supervised classification of 12 panchromatic satellite images of the seven known Ross Sea colonies. We used regression to predict adult bird counts at the inaccessible colonies by relating the number of pixels classified as “penguin” in the satellite images of the accessible colonies to corresponding known adult bird counts from aerial photographs or ground counts. While our analysis was hampered by excessive guano and shadows, we used satellite imagery to differentiate between relatively small (<3,000 adult birds) and larger colonies (>5,000 adult birds). Remote sensing technology is logistically less intense and less costly than aerial or ground censuses when the objective is to document penguin presence and/or large emperor penguin population changes (e.g., catastrophic changes). Improvements expected soon in the resolution of the satellite images should allow for more accurate abundance estimates.     

Nutritional effects of supplementary diets on brood development,biological activities and honey production of Apis mellifera L

The present research work was conducted to assess the impact of nutrient-enriched diet on the physiological activities and subsequently honey yield. Eighteen colonies of Apis mellifera L. were selected from Dera Ismail Khan region, KPK, Pakistan, during the winter and summer seasons, 2019–2020. Five pollen supplement diets were prepared and provided to screen out the palatable one to be fed as pollen alternative nutrition to bee bread. Results of diet consumption regarding mean data for consumption rate displayed that soybean flour enriched artificial diet was maximally consumed (74.34 g) by honey bees per week. Minimum consumption was observed for grinded groundnut enriched diet (64.62 g) which was relatively lesser than the other tested artificial diets. Results of area of worker brood disclosed that soybean flour fortified diet (1489.27 cm²/colony) statistically noteworthy than the other artificial diets whereas control (463.51 cm²/colony) was least effective. Highest bee strength (10.00 bee frames/colony) was noted in the bee colonies fed with soybean flour fortified diet, date paste (8.0 bee frames/colony) was the next effective one, among the tested pollen replacement diets whereas relatively least (5 bee frames/colony) was noticed in case of grinded groundnut. Highest body weight (12.41 g) of neonate bees was noted in case of soybean enriched diet while lowermost (5.31 g) was noted in control bees. Results of wax cell built up and foraging efficiency were also superior in artificial diets than respective control bees. Hence, artificial diets especially soybean-enriched pollen alternative diet can boost up the physiology of honey bee leading to increased honey yield and profit.     

The raiding success of Pheidole megacephala on other ants in both its native and introduced ranges

We studied the behaviour of the invasive African myrmicine ant, Pheidole megacephala, when confronted with colonies of other common ant species in Cameroon, a part of its native range, and in Mexico, where it has been introduced. P. megacephala raided the nests of the other ants in both cases. Eleven species out of 12 put up a rather strong resistance to raiding P. megacephala workers in Cameroon compared to only three species out of 11 in Mexico, where only colonies of Solenopsis geminata, Dorymyrmex pyramicus and Dolichoderus bispinosus resisted these raids. We conclude that P. megacephala's heightened ability to successfully raid colonies of competing ants may help explain its success and the decline of native ants in areas where it has been introduced.     

奶糖的样品前处理优化与微生物检测结果影响因素相关性讨论

本文的主要研究目的是找到针对不同奶糖样品最适合的前处理方法、快速有效的检测方法以及影响检测结果的相关性因素。通过溶化温度、溶化方式、溶化时间等不同实验条件,找出了能满足不同奶糖菌落总数检测要求的样品前处理方法,即将25 g奶糖样品称取到预温至45℃的225 m L灭菌生理盐水中,在45℃气浴恒温振荡器中以220 r/min振荡11 min,使奶糖完全溶化。同时由于奶糖中有些菌落会蔓延生长,为了不影响计数结果,在倾入平板计数琼脂培养基冷却后再在其表面覆盖一层5 m L培养基抑制菌落蔓延,对抑制效果不佳的使用光学放大菌落计数器计数,以保证最终检测结果的准确性。不同奶糖中水分、营养含量及pH相差不大,实验结论表明与其菌落总数检测结果高低无相关性。通过36℃培养24 h与48 h菌落总数检测结果没有明显差异,可以将培养24 h的检测结果作为参考。     

现生微生物群落形态研究及其对解释埃迪卡拉生物群化石属性的启示

通过对常见微生物种类进行纯培养获得多种微生物菌落形态,并将其与埃迪卡拉生物群化石形态进行对比研究,发现：1）盘状化石Aspidella与圆盘形菌落的轮廓和放射状分布的小脊具有相似性;2）“rangeomorphs”分支状化石与具有次级分支结构的菌落具有某些相似性;3）五边形似棘皮动物化石Arkaruaadami与五边形菌落较为相似;4）两侧对称类化石Kimberella与圆盘形边缘具放射状脊的菌落的表面形态非常相似;5）盘状化石Az—bumaresbrunsae与圆盘形表面具辐射状脊的菌落的轮廓和表面纹饰分布极为相似。以上对比结果表明部分埃迪卡拉生物群化石与微生物菌落形态具有一定的相似性。本研究为埃迪卡拉生物群化石生物属性的解译提供了新思路。