Die Ausbreitung der Melanoblasten bei den Embryonen verschiedenfarbiger Hühner

Summary The first melanoblasts are found in the embryos of the black Rheinländer and Plymouth Rock chickens at the fifth day of development in the occipital and lumbal region. The further spread of the pigment cells is equal in both races. But at the eight day the pigmented area is much more extended in the Plymouth Rocks. These embryos possess at this time more than twice the amount of melanoblasts which are more pigmented than in Rheinländer embryos of the same age. During the further development this differences are equalized.In both races the colour pattern of the chickens are different and have no similarities with the pattern of adult animals. The different patterns of chickens may be explained by time-dependent, genetic differences during the differentiation of the melanoblasts. The colouration in the adult fowls must be due to different genetic factors, which become effective during the development of the juvenile feathers.     

Heterotrophic utilization of extracellular products of phytoplankton in a tropical estuary

Bacterial uptake of algal exudates has been estimated in a tropicalestuary, Dona Paula, where the seasonal fluctuations in hydrographicand nutrient parameters as well as dissolved organic matterconcentrations and phytoplankton species composition are dominatedby the monsoon regime. A close coupling existed between algaland bacterial trophic levels. Algal exudation products wererapidly assimilated with short turnover times. An average 80%of the excreted material was removed by heterotrophic bacteriaand there was a significant correlation between algal extracellularproduction and net bacterial uptake of algal exudates.     

Energetic aspects of the gliding mitility of mycoplasmas

This report reviews the question of whether mycoplasma gliding is an active form of surface translocation or a biased Brownian motion. The theoretical calculations presented here, along with recently described experimental observations, unequivocally prove that the motility of some mycoplasmas—at least, however, ofMycoplasma mobile—requires a cellular energy source. In an accompanying report we present further experimental evidence supporting this conclusion.     

Transport of erythrocytes by gliding cells ofMycoplasma mobile 163K

Gliding cells ofMycoplasma mobile 163K are able to transport attached sheep erythrocytes (RBC). The interaction between the mycoplasmas and the RBC was microscopically investigated with Nomarski interference-contrast microscopy and documented by microcine-matography and sequences of single-frame photomicrographs. Two morphological types of attachment are described, and the strength of interaction is calculated.     

Kurze Mitteilungen

Summary To the creamy-yellow colored bases of the rump feathers ofDucula bicolor adheres lipoid and noncolored powder. It is supposed, that the lipoid contains the creamy colour, which apparently is no carotenoid.     

Production cell analysis and compound-based boosting of small extracellular vesicle secretion using a generic and scalable production platform

Extracellular vesicles (EVs) are a novel format of advanced therapeutical medicinal products (ATMPs). They can act regenerative or immune-modulatory as cell therapy substitutes or as a platform for designer exosomes. The biotechnological production of therapeutic EVs is still very much uncharted territory so standardized host cells, production setups, and isolation methods are not yet implemented. In this work, we present a tangential flow filtration (TFF) and fast-performance liquid chromatography (FPLC)-based size exclusion chromatography (SEC) purification setup that is compatible for industry applications. Moreover, we evaluated a series of potential host cell lines regarding their EV productivity, characteristics, and biological functionality. It was found that telomerase-immortalized Wharton's jelly mesenchymal stromal cells (WJ-MSC/TERT273) secrete high amounts of EVs per cell with regenerative capabilities. On the other hand, Cevec's amniocyte producer cells® (CAP®) and human embryonic kidney (HEK293) suspension cells are suitable platforms for designer EVs with high yields. Finally, we aimed to boost the EV secretion of HEK293 cells via chemical adjuvants and verified four compounds that heighten cellular EV secretion in a presumably cAMP-dependent manner. A combination of fenoterol, iodoacetamide, and dinitrophenol increased the EV yield in HEK293 cells threefold and cellular secretion rate fivefold.     

Family Kinship Patterns and Female Sex Work in the Informal Urban Settlement of Kibera, Nairobi, Kenya

A basic ecological and epidemiological question is why some women enter into commercial sex work while other women in the same socio-economic environment never do. To address this question respondent driven sampling principles were adopted to recruit and collect data for 161 female sex workers and 159 same aged women who never engaged in commercial sex in Kibera, a large informal settlement in Nairobi, Kenya. Univariate analysis indicated that basic kinship measures, including number of family members seen during adolescence and at present, not having a male guardian while growing up, and earlier times of ending relationships with both male and female guardians were associated with commercial sex work in Kibera. Multivariate analysis via logistic regression modeling showed that not having a male guardian during childhood, low education attainment and a small number of family members seen at adolescence were all significant predictors of entering sex work. By far the most important predictor of entering sex work was not having any male guardian, e.g., father, uncle, older brother, etc. during childhood. Results are interpreted in light of the historic pattern of sub-Saharan African child fostering and their relevance for young women in Kibera today.     

Untersuchungen über die Ernährung einiger Myxobakterien

Ohne ZusammenfassungDissertation der Mathem.-Naturwiss. Fakultät der Universität Göttingen.