Sizes of granular vesicles in the rat median eminence,with special reference to the zona granulosa

Summary A quantitative evaluation has been made of the sizes of neuronal granular vesicles (GV) in different (sub-)zones of the rat median eminence. On the basis of the frequency distribution of the mean sizes of the GV in the individual nerve profiles, at least 4 tentative categories of nerve profiles may be distinguished. However, available data do not permit characterization of nerve fibre categories in terms of neurohormone and/or neurotransmitter storage. From dorsal to ventral the palisade zone shows a decrease in mean size of GV; furthermore, the relative number of nerve profiles characterized by small GV (mean size smaller than 112 nm) increases. In contrast, the GV in the zona granulosa, that part of the external zone of the median eminence ventral to the palisade zone, are of relatively large size. Qualitative observations indicate that the zona granulosa may be regarded as an area for both storage and release of biologically active substances. We are grateful to Mrs. R.M.Y. Hartsteen for technical assistance, to Miss P.C. Delfos and Mr. W. van den Oudenalder for photographic assistance and to Prof. J. Moll for helpful criticism.     

Co-transfer of two plasmids determining bacteriocin production and sucrose utilization in Streptococcus faecium

Abstract Streptococcus faecium strain 25 produced a bacteriocin (enterococcin Sf25), metabolized sucrose and contained three plasmids of 2.4, 4.7 and 13.0 MDa. Plasmids Sfp2.4 and Sfp4.7 were cotransferred in a filter mating procedure to sucrose negative and bacteriocin negative S. faecium strain M16. Strain M16 harboured a nonselftransferable plasmid Sfp 19.1 MDa, which was responsible for erythromycin resistance. Transcipient cells of S. faecium M16 contained the 19.1-MDa plasmid and plasmids Sfp2.4 and Sfp4.7, produced the enterococcin Sf25 and gained the ability to degrade sucrose.     

Studien über die endokrinen Zellen des Magendarmtraktes

Zusammenfassung Die serotoninhaltigen, nach Formaldehydbedampfung im UV-Licht gelbfluoreszierenden EC-Zellen im Magendarmepithel wurden bei normalen und bei tryptophanfrei ernährten Ratten untersucht. Bei Kontrolltieren ist die Zahl der EC-Zellen, bezogen auf die Schleimhautfläche, im Duodenum größer als im Pylorus. Im Duodenum sind die EC-Zellen etwa gleichmäßig auf Oberflächen- und Drüsenepithel verteilt, im Pylorus ganz überwiegend im Drüsenepithel lokalisiert. Die Brunnerschen Drüsen besitzen keine EC-Zellen. Tryptophanfreie Diät führt zu starker Abnahme des Serotoningehalts der EC-Zellen, nach Umsetzung auf Normalkost steigt er wieder an. — Die Ergebnisse sprechen weiterhin dafür, daß die EC-Zelle sowohl Speicher- als auch Syntheseort von Serotonin ist. Dabei kommt Serotonin in der EC-Zelle wahrscheinlich in zwei Fraktionen vor, nämlich zytoplasmatisch gelöst und granulagebunden. Die histochemischen Nachweismethoden für Serotonin, Möglichkeiten des Eingriffs in die verschiedenen Syntheseschritte des Serotonins und deren Spezifität in bezug auf die EC-Zelle als physiologischem Ort der Serotoninsynthese werden diskutiert.

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Studies on the endocrine cells of the gastrointestinal tractII. Fluorescence microscopy of the EC-cells after tryptophan-free diet

Summary The serotonin-containing EC-cells of the gastro-intestinal mucosa, which show yellow fluorescence after treatment with gaseous formaldehyde, were investigated in the rat after normal and tryptophan-free nourishment. In control animals the number of EC-cells, related to epithelium area is higher in the duodenum than in the pyloric region. In the duodenum the EC-cells show about the same distribution in surface epithelium and gland epithelium. In the pyloric region EC-cells are localized predominantly in the gland epithelium. No EC-cells were found in the Brunner glands. After tryptophan-free diet the serotonin-level of the EC-cells strongly decreases; serotonin-level increases after return to normal nourishment. The results also suggest, that serotonin is synthesized as well as stored in the EC-cell and that it occurs in two fractions: bound to granules and dissolved in the cytoplasm. Discussion deals with the histochemical methods for determination of serotonin, the possibilities of influencing the pathways of serotonin metabolism and the specificity of these possibilities concerning the EC-cell as the physiological site of serotonin synthesis.

Mit Unterstützung durch die Deutsche Forschungsgemeinschaft, Antrag Fo 77, 1–4.     

The potential for and constraints on the evolution of compensatory ability in Asclepias syriaca

To investigate the potential for and constraints on the evolution of compensatory ability, we performed a greenhouse experiment using Asclepias syriaca in which foliar damage and soil nutrient concentration were manipulated. Under low nutrient conditions, significant genetic variation was detected for allocation patterns and for compensatory ability. Furthermore, resource allocation to storage was positively, genetically correlated both with compensatory ability and biomass when damaged, the last two being positively, genetically correlated with each other. Thus, in the low nutrient environment, compensatory ability via resource allocation to storage provided greater biomass when damaged. A negative genetic correlation between compensatory ability and plant biomass when undamaged suggests that this mechanism entailed an allocation cost, which would constrain the evolution of greater compensatory ability when nutrients are limited. Under high nutrient conditions, neither compensatory ability nor allocation patterns predicted biomass when damaged, even though genetic variation in compensatory ability existed. Instead, plant biomass when undamaged predicted biomass when damaged. The differences in outcomes between the two nutrient treatments highlight the importance of considering the possible range of environmental conditions that a genotype may experience. Furthermore, traits that conferred compensatory ability did not necessarily contribute to biomass when damaged, demonstrating that it is critical to examine both compensatory ability and biomass when damaged to determine whether selection by herbivores can favor the evolution of increased compensation. Received: 2 April 1999 / Accepted: 21 September 1999     

MicroID2: A Novel Biotin Ligase Enables Rapid Proximity-Dependent Proteomics

Identifying protein–protein and other proximal interactions is central to dissecting signaling and regulatory processes in cells. BioID is a proximity-dependent biotinylation method that uses an “abortive” biotin ligase to detect proximal interactions in cells in a highly reproducible manner. Recent advancements in proximity-dependent biotinylation tools have improved efficiency and timing of labeling, allowing for measurement of interactions on a cellular timescale. However, issues of size, stability, and background labeling of these constructs persist. Here we modified the structure of BioID2, derived from Aquifex aeolicus BirA, to create a smaller, highly active, biotin ligase that we named MicroID2. Truncation of the C terrminus of BioID2 and addition of mutations to alleviate blockage of biotin/ATP binding at the active site of BioID2 resulted in a smaller and highly active construct with lower background labeling. Several additional point mutations improved the function of our modified MicroID2 construct compared with BioID2 and other biotin ligases, including TurboID and miniTurbo. MicroID2 is the smallest biotin ligase reported so far (180 amino acids [AAs] for MicroID2 versus 257 AAs for miniTurbo and 338 AAs for TurboID), yet it demonstrates only slightly less labeling activity than TurboID and outperforms miniTurbo. MicroID2 also had lower background labeling than TurboID. For experiments where precise temporal control of labeling is essential, we in addition developed a MicroID2 mutant, termed lbMicroID2 (low background MicroID2), that has lower labeling efficiency but significantly reduced biotin scavenging compared with BioID2. Finally, we demonstrate utility of MicroID2 in mass spectrometry experiments by localizing MicroID2 constructs to subcellular organelles and measuring proximal interactions.     

Evaluation of nutrients and related environmental factors for wolfberry (Lycium barbarum) fruits grown in the different areas of China

The wolfberry (Lycium barbarumL.) fruit has been used in traditional Chinese medicine and food, but fruits grown in various geographic areas are significantly different in quality and content of functional components. In this study, we tested the internal nutritional ingredients and related environmental factors using forty-two wolfberry fruits collected from seven wolfberry producing regions in China (Yinchuan and Zhongning in Ningxia, Jingyuan in Gansu, Nuomuhong Farm in Qinghai,Hangjinhouqi and Wulateqianqi in Inner Mongolia, and Jinghe in Xinjiang). The nutritional ingredients of the forty-two wolfberry fruits are dependent on the environment. Correlation analysis revealed that the amount of nutrients was highly related to each other. Based on the analysis ofratio of total sugar to betaine (sugar-alkali ratio), we have successfully established quality standards for the wolfberry based on the levels of betaine and sugar. The standards were as follows: high betaine low sugar (sugar-alkali ratio≤15.1), high betaine medium sugar (15<sugar-alkali ratio≤60), medium betaine medium sugar (60<sugar-alkali ratio≤121), medium betaine high sugar (121<sugar-alkali ratio≤165), and low betaine high sugar (sugar-alkali ratio>165). Zhongning of Ningxia is the geo-authentic producing region of the wolfberry, whereby the wolfberries are rich in main pharmacological ingredients Lycium barbarum polysaccharide (LBP) and three trace elements (iron, manganese and selenium) and medium sugar-alkali ratio. In addition, the correlation analysis showed that both the altitude and average temperature difference between day and night had positive effects on the wolfberry flavonoids content but the annual sunshine duration negatively affected the betaine contents of the wolfberry fruit.     

Stimulation of glucose utilization and lactate production in cultured human fibroblasts by thyroid hormone

Human dermal fibroblasts were obtained by harvesting outgrowing cells from the dermal tissue explants and cultured in Dulbecco's modified Eagle medium containing 10% fetal calf serum. After the cells reached confluency, culture was continued in the medium containing calf serum which was deprived of thyroid hormone by the treatment with activated charcoal. These fibroblasts were responsive to exogeneously added thyroid hormone (triiodothyronine) at physiological concentrations, resulting in enhanced utilization of glucose and production of lactate. This stimulation by thyroid hormone was dependent upon the length of exposure to the hormone and its concentration.The hormone did not show any effects on cellular DNA and protein content. The experimental system described above seems to be easy to reconstitute and should be useful for the elucidation of the mechanism of thyroid hormone action.     

Studies on the population dynamics of the assassin bug,Agriosphodrus dohrni Signoret,in relation to resting site utilization

Population Ecology -