Ribonuclease III: new sense from nuisance.

RNases play an important role in the processing of precursor RNAs, creating the mature, functional RNAs. The ribonuclease III family currently is one of the most interesting families of endoribonucleases. Surprisingly, RNase III is involved in the maturation of almost every class of prokaryotic and eukaryotic RNA. We present an overview of the various substrates and their processing. RNase III contains one of the most prominent protein domains used in RNA-protein recognition, the double-stranded RNA binding domain (dsRBD). Progress in the understanding of this domain is summarized. Furthermore, RNase III only recently emerged as a key player in the new exciting biological field of RNA silencing, or RNA interference. The eukaryotic RNase III homologues which are likely involved in this process are compared with the other members of the RNase III family.     

Formin-like 1 (FMNL1) Is Regulated by N-terminal Myristoylation and Induces Polarized Membrane Blebbing

The formin protein formin-like 1 (FMNL1) is highly restrictedly expressed in hematopoietic lineage-derived cells and has been previously identified as a tumor-associated antigen. However, function and regulation of FMNL1 are not well defined. We have identified a novel splice variant (FMNL1γ) containing an intron retention at the C terminus affecting the diaphanous autoinhibitory domain (DAD). FMNL1γ is specifically located at the cell membrane and cortex in diverse cell lines. Similar localization of FMNL1 was observed for a mutant lacking the DAD domain (FMNL1ΔDAD), indicating that deregulation of autoinhibition is effective in FMNL1γ. Expression of both FMNL1γ and FMNL1ΔDAD induces polarized nonapoptotic blebbing that is dependent on N-terminal myristoylation of FMNL1 but independent of Src and ROCK activity. Thus, our results describe N-myristoylation as a regulative mechanism of FMNL1 responsible for membrane trafficking potentially involved in a diversity of polarized processes of hematopoietic lineage-derived cells.     

Identification of Cell Cycle Dependent Interaction Partners of the Septins by Quantitative Mass Spectrometry

The septins are a conserved family of GTP-binding proteins that, in the baker''s yeast, assemble into a highly ordered array of filaments at the mother bud neck. These filaments undergo significant structural rearrangements during the cell cycle. We aimed at identifying key components that are involved in or regulate the transitions of the septins. By combining cell synchronization and quantitative affinity-purification mass-spectrometry, we performed a screen for specific interaction partners of the septins at three distinct stages of the cell cycle. A total of 83 interaction partners of the septins were assigned. Surprisingly, we detected DNA-interacting/nuclear proteins and proteins involved in ribosome biogenesis and protein synthesis predominantly present in alpha-factor arrested that do not display an assembled septin structure. Furthermore, two distinct sets of regulatory proteins that are specific for cells at S-phase with a stable septin collar or at mitosis with split septin rings were identified.Complementary methods like SPLIFF and immunoprecipitation allowed us to more exactly define the spatial and temporal characteristics of selected hits of the AP-MS screen.     

Morphologische und entwicklungsgeschichtliche Untersuchungen an Chrysophyceen

Ohne Zusammenfassung     

Sensing vascular distension in skeletal muscle by slow conducting afferent fibers: neurophysiological basis and implication for respiratory control.

This review examines the evidence that skeletal muscles can sense the status of the peripheral vascular network through group III and IV muscle afferent fibers. The anatomic and neurophysiological basis for such a mechanism is the following: 1) a significant portion of group III and IV afferent fibers have been found in the vicinity and the adventitia of the arterioles and the venules; 2) both of these groups of afferent fibers can respond to mechanical stimuli; 3) a population of group III and IV fibers stimulated during muscle contraction has been found to be inhibited to various degrees by arterial occlusion; and 4) more recently, direct evidence has been obtained showing that a part of the group IV muscle afferent fibers is stimulated by venous occlusion and by injection of vasodilatory agents. The physiological relevance of sensing local distension of the vascular network at venular level in the muscles is clearly different from that of the large veins, since the former can directly monitor the degree of tissue perfusion. The possible involvement of this sensing mechanism in respiratory control is discussed mainly in the light of the ventilatory effects of peripheral vascular occlusions during and after muscular exercise. It is proposed that this regulatory system anticipates the chemical changes that would occur in the arterial blood during increased metabolic load and attempts to minimize them by adjusting the level of ventilation to the level of muscle perfusion, thus matching the magnitudes of the peripheral and pulmonary gas exchange.     

Single pot sequential crystallization-distillation as a new purification procedure

A new purification procedure exploiting the simultaneous presence of a solid, liquid, and gas phase in a low surface area system is proposed and discussed. The assumptions of vanishingly low diffusion coefficients in the solid phase and that of the presence of a single “effective impurity” allow to plan the sequence of operations starting from the knowledge of just the melting and boiling points of the substance to be purified and of those of the “effective impurity”. Examples and results are presented.     

Tracing of cell lineage in embryonic development of Phallusia mammillata (ascidia) by vital staining of mitochondria

Vital staining of mitochondria with a fluorescent dye 3,3′-diethyloxacarbocyanine was used to follow cell lineage in embryos of Phallusia mammillata. The results agree in general with the plan established by Conklin in 1905. Strong fluorescence migrated after fertilization similarly to the pigment of the “yellow crescent” in Styela. Later, fluorescence segregated into muscle cell primordia, but not into mesenchyme cells. An animal hemisphere cell, b 8.17 also exhibited strong fluorescence and joined a group of muscle primordia, very likely becoming a muscle cell itself. In the tadpole, all the tail muscle cells were fluorescent. Fluorescence was also noticed in nerve cell primordia of the vegetal hemisphere, particularly in the cell A 8.16 whose descendants appeared to become part of the sensory vesicle which was strongly fluorescent in the tadpole. The usefulness of this type of vital staining in following cell lineage of colorless embryos is stressed.