Cell interactions in the generation of chaetae pattern inDrosophila

Summary We have already shown that theachaetae-scute complex (AS-C) ofDrosophila is regulated by two genes,hairy andextramacrochaetae. Using mutants in these genes, we have analysed how different levels of expression of AS-C affect the pattern of chaetae. The results indicate that the spatial distribution of chaetae results from cell interactions, probably by a mechanism of lateral inhibition. The results are discussed in view of the different theories of pattern formation.     

Seasonal trends in morpho-physiological attributes and bioactive content of Valeriana jatamansi Jones under full sunlight and shade conditions

Valeriana jatamansi Jones, an important medicinal herb of the Himalayan region, is an essential source of many therapeutic compounds and is traded/consumed in very high volume. The hypothesis of this study was that different seasons and light conditions may affect the content of medicinally valuable components with changes in the morpho-physiological attributes of the plant. Growing plants under suitable light conditions and harvesting of appropriate plant parts in optimum season is crucial for harnessing the full potential of the crop. Thus, the study was carried out to determine the seasonal response of V. jatamansi plants (genetically identical plants of same age) in terms of growth and phytochemical content under two different light conditions (full sunlight and 50% shade). During all seasons, growth parameters (plant height, leaf number, leaf area, relative water content, plant biomass) and the principle bioactive compounds (valerenic acid) were higher under shade conditions, while total flavonoids, tannins, phenolic compounds and antioxidant activities were higher under full sunlight conditions. HPLC analysis revealed that valerenic acid and most of the phenolic content were higher during summer season, especially in leaf part of the plant. The study suggested harvesting of V. jatamansi plants (especially leaf), during summer season to harness high quality raw material and to prevent loss of belowground parts. This strategy can be adopted by farmers for large scale cultivation of species.Supplementary InformationThe online version of this article contains supplementary material available at 10.1007/s12298-021-00944-0     

Diversity of plants in cocoa agroforests in the humid forest zone of Southern Cameroon

In the humid forest zone of Southern Cameroon, farmers generally associate cocoa with native and exotic trees in complex agroforestry systems. Despite the socio-economic and ecological importance of these systems, few studies have investigated their plant composition. We investigated tree composition of cocoa agroforests along a gradient of market access, population density and resource use intensity in the humid forest zone of southern Cameroon, comprising (i) the sub-region of Yaoundé, (ii) the sub-region of Mbalmayo, and (iii) the sub-region of Ebolowa. Market access, population density and resource use intensity all decreased from the first to the third sub-region. We quantified the diversity of tree species associated with cocoa within individual agroforests, among agroforests in the same region, and among the three sub-regions, and classified the tree species according to their main uses. A total of 9.1 ha belonging to 60 cocoa agroforests were inventoried in 12 villages. We encountered a total of 206 tree species with an average of 21 tree species per agroforest. In the more urbanized area around Yaoundé, agroforests were less diverse than in the other sub-regions. In all of the agroforests, food producing tree species tended to be more frequent than other species. Two thirds of the food trees were native forest species and one third was introduced. From Ebolowa to Yaoundé, the density of food producing trees doubled and the density of exotic food-producing species increased relative to native species. Some local species producing high-value non-timber forest products were found in the agroforests, but their density was far lower than that of exotic tree species. The agroforests also provide medicine, charcoal and other products for household consumption and sale. We conclude that unless there are specific efforts to promote local forest tree species in cocoa agroforests, these will progressively lose importance with increasing market access, population pressure and land use intensity.     

蚕茧近红外反射（NIR）光谱的模式识别──Ⅰ．对雌雄鲜茧、死笼茧的非破坏性识别

探讨了利用蚕茧近红外反射光谱识别雌雄茧、死笼茧的方法及可行性。采用６２５０型近红外光谱分析仪,从波长６８０ｎｍ到１２３５ｎｍ对２０５颗鲜茧做了非破坏性扫描测试,用逐步判别方法从一、二阶导数光谱数据中抽取特征向量,以此特征向量建立Ｂａｙｅｓ判别函数,对３７５个检验样本进行识别,其符合率达９５．７％,该方法明显优于以茧的重量和大小判别雌雄的方法。实验结果还表明,雌雄茧近红外反射光谱的差别,主要是由于蚕蛹性质不同所致,而与茧层的关系不大。     

Cell bathing medium as a target for non thermal effect of millimeter waves

Non thermal (NT) effect of direct radiation 4 Hz-modulated 90–160 GHz of Millimeter Waves (MMW) and preliminary MMW-treated physiological solution (PS) influence were studied on snail isolated neuron, rat's brain tissue hydration and skin penetration. It was shown that the 4 Hz-modulated low intensity 90–160 GHz MMW direct radiation and MMW-treated PS leads to on single neuron shrinkage, skin and brain tissue dehydration. On the basis of obtained data it was suggested that the cell bathing aqua medium serve as a target through which the NT effect of MMW on cell hydration is realized. The MMW-induced brain tissue dehydration can considering as consequence of MMW-induced skin water structural changes leading to unknown messenger formation able to modulate the brain cell hydration. The extrasensitivity of cell hydration to low intensity of MMW radiation allow to recommend cell hydration as a cellular marker for estimation of the NT biological effect of MMW on cells and organisms.     

Speed encoding in correlation motion detectors as a consequence of spatial structure

For animals to carry out a wide range of detection, recognition and navigation tasks, visual motion signals are crucial. The encoding of motion information has therefore, attracted much attention in the experimental and computational study of brain function. Two main alternative mechanisms have been proposed on the basis of behavioural and physiological experiments. On one hand, correlation-type and motion energy detectors are simple and efficient in the design of their basic mechanism but are tuned to temporal frequency rather than to speed. On other hand, gradient-type motion detectors directly represent an estimate of speed, but may require more demanding processing mechanisms. We demonstrate here how the temporal frequency dependence observed for sine-wave gratings can disappear for less constrained stimuli, to be replaced by responses reflecting speed for stimuli like square waves when a phase-sensitive detection mechanism is employed. We conclude from these observations that temporal frequency tuning is not necessarily a limitation for motion vision based on correlation detectors, and more generally demonstrate in view of the typical Fourier composition of natural scenes, that correlation detectors operating in such environments can encode image speed. In the context of our results, we discuss the implications of the loss of phase sensitivity inherent in using a linear system approach to describe neural processing.     

Genetic and developmental analyses of chaetae pattern formation in Drosophila tergites

Summary The role of the achaete-scute complex and extramacrochaetae, Notch, Delta, Enhancer of split and Hairless genes in chaeta patterning in Drosophila tergites was studied in genetic mosaics and in mutant combinations. The mutant phenotypes of different alleles of each gene can be ordered in characteristic topographical seriations. These seriations are related to the pattern of proliferation of histoblasts and the time of singularization of sensory organ mother cells from surrounding epidermal cells. Genetic mosaics of lethal alleles show that these genes are fundamentally involved in this singularization and subsequent differentiation. The study of mutant combinations of alleles of these genes reveals specific relationships of epistasis and synergism between them. The results suggest that spatial and temporal variations in achaete-scute complex functional products in cells, modulated by the activity of other genes involved in signal transduction, define the patterned differentiation of sensory organs in tergites. Offprint requests to: A. García-Bellido     

春季小降雨事件对科尔沁沙地尖头叶藜萌发的影响

通过人工模拟降雨试验研究了科尔沁沙地优势草本植物尖头叶藜萌发和幼苗建成对春季小降雨事件(2、4、8 mm和自然降雨)的响应。结果表明:不同降雨处理对尖头叶藜的萌发和幼苗建成有显著影响(P0.05)。8mm降水量是促使尖头叶藜萌发的最小降雨阈量。不同降雨量处理下尖头叶藜萌发数量大小顺序为:8mm处理对照4 mm处理2mm处理;而高度和冠幅依次是2 mm处理(2.23 cm和7.15 cm2.)对照(2.03 cm和6.21 cm2)4mm处理(1.86 cm和5.01 cm2)8mm处理(1.48cm和4.72 cm2);降雨量为8mm的地上生物量最多(45.26 g/m2),对照为35.49g/m2、4mm处理为26.54g/m2、2mm处理为15.26g/m2。尖头叶藜幼苗的水分利用效率与每次降水量呈显著地正相关关系,随着每次降雨量的增大地上生物量逐渐增大。本试验中各处理的总降雨量一致,但地上生物量不同且差异显著。每次降雨量×降雨次数的分布状况影响了尖头叶藜幼苗的地上生物量。科尔沁沙地尖头叶藜萌发及其幼苗建成在密度、形态和水分利用效率和地上生产力上对不同模式的小降雨做出了积极的响应。     

HyphArea—Automated analysis of spatiotemporal fungal patterns

In phytopathology quantitative measurements are rarely used to assess crop plant disease symptoms. Instead, a qualitative valuation by eye is often the method of choice. In order to close the gap between subjective human inspection and objective quantitative results, the development of an automated analysis system that is capable of recognizing and characterizing the growth patterns of fungal hyphae in micrograph images was developed. This system should enable the efficient screening of different host-pathogen combinations (e.g., barley—Blumeria graminis, barley—Rhynchosporium secalis) using different microscopy technologies (e.g., bright field, fluorescence). An image segmentation algorithm was developed for gray-scale image data that achieved good results with several microscope imaging protocols. Furthermore, adaptability towards different host-pathogen systems was obtained by using a classification that is based on a genetic algorithm. The developed software system was named HyphArea, since the quantification of the area covered by a hyphal colony is the basic task and prerequisite for all further morphological and statistical analyses in this context. By means of a typical use case the utilization and basic properties of HyphArea could be demonstrated. It was possible to detect statistically significant differences between the growth of an R. secalis wild-type strain and a virulence mutant.