Bacterial division: another way to box in the ring

Proper placement of the cell division site in some rod-shaped bacteria requires two different negative regulatory systems, nucleoid occlusion and the Min proteins. Caulobacter crescentus lacks these systems, but recent work has uncovered a novel regulator that achieves the same goals.     

p53 and tumor surveillance: Killer finds way to recruit assassins

Comment on: Li H, et al. Cell Cycle 2011; 10: 3346-58.     

Melanopsin: another way of signaling light

A subset of melanopsin-expressing retinal ganglion cells has been identified to be directly photosensitive (pRGCs), modulating a range of behavioral and physiological responses to light. Recent expression studies of melanopsin have provided compelling evidence that melanopsin is the photopigment of the pRGCs. However, the mechanism by which melanopsin transduces light information remains an open question. This review discusses the signaling pathways that may underlie melanopsin-dependent phototransduction in native pRGCs, as well as the many exciting challenges ahead.     

Phytochromes and flowering: legumes do it another way

Phytochromes have a crucial role in the regulation of flowering in many plants, but the underlying molecular mechanisms vary among species. Recently, Lin et al. described a unique phytochrome A (phyA)-controlled photoperiodic flowering pathway in soybean (Glycine max), revealing a novel mechanism for photoperiodic regulation of flowering.     

Thermoregulation: an orphan receptor finds its way in the cold

The hypometabolic state of torpor is a widely utilized and well-orchestrated response to food shortage. A new study shows that the melatonin-related orphan receptor GPR50 plays an important function in metabolic regulation for entry into torpor.     

Regulating RIPK1: another way in which ULK1 contributes to survival

ABSTRACT

The mammalian ULK1 is the central initiating kinase of bulk and selective macroautophagy/autophagy processes. In the past, both autophagy-relevant and non-autophagy-relevant substrates of this Ser/Thr kinase have been reported. Here, we describe our recent finding that ULK1 also regulates TNF signaling pathways. We find that inhibition of autophagy or specifically ULK1 increases TNF-induced cell death. This autophagy-independent pro-survival function of ULK1 is mediated via the phosphorylation of RIPK1 at Ser357. RIPK1 is the central mediator of pro-inflammatory or pro-death signaling pathways induced by TNF, and ULK1-dependent phosphorylation regulates RIPK1 activation and distribution to different intracellular signaling complexes. Our results indicate that ULK1 exerts a cyto-protective function not only by initiating autophagy, but also by controlling RIPK1-mediated cell death.     

Electrical noise measurements on red beet vacuoles : another way to detect the ATPase activity

The vacuolar potential (V_vac) and its fluctuations were recorded in red beet vacuoles (Beta vulgaris L.). Measurements with vacuoles in their suspension medium gave V_vac = 10 ± 2 millivolts (referred to the external medium) when 3 molar KCl microelectrodes were used. Buffering the microelectrode filling solution at pH 7.7 reversed the sign of the potential: V_vac = −7 ± 2 millivolts. The magnitude of the potential fluctuations was lowered by dilution (5-1000 times) with the suspension medium containing components released by the cells during the mechanical preparation. Fluctuations were decreased by 50 millimolar KNO₃ while they were enhanced by 5 millimolar ATP-Mg. No noticeable change in membrane resistance was detected. The presence of an ATPase bound to the tonoplast may explain the recorded noise spectra. These spectra imply a close connection between the rate of ATPase functioning and the magnitude of ionic fluxes across the tonoplast. It is suggested that noise analysis could be used to detect ATPase (or related enzyme) activity in vacuoles. Possible use of H⁺ diffusion through a buffered microelectrode, to modify intravacuolar pH, is also suggested.     

Beta-specificity: The turnover of host species in space and another way to measure host specificity

Host specificity is often measured as the number of host species used by a parasite, or as their phylogenetic diversity; both of these measures ignore the larger scale component of host use by parasites. A parasite may exploit very few host species in one locality but these hosts may be substituted for completely different species elsewhere; in contrast, another parasite may exploit many host species in one locality, with the identity of these hosts remaining the same throughout the parasite’s geographical range. To capture these spatial nuances of host specificity, we propose to use an index for host species turnover across localities, or beta-specificity (β_SPF), that is derived from studies of spatial patterns in plant and animal diversity. We apply this index to fleas parasitic on small mammals to show that: (i) it is statistically independent of traditional or “local” measures of host specificity as well as of “global” measures of host specificity, and (ii) it is also independent of the size of the geographical area studied or the sampling effort put into collecting hosts and parasites. Furthermore, the distribution of β_SPF values among flea species shows a significant phylogenetic signal, i.e. related flea species have more similar β_SPF values than expected by chance. Nevertheless, most possible combinations of either local specificity (alpha-specificity) or global (gamma-specificity) and beta-specificity are observed among flea species, suggesting that adding a spatial component to studies of host use reveals a new facet of specificity. The measure presented here provides a new perspective on host specificity on a scale relevant to studies on topics ranging from biogeography to evolution and may underlie the rate and extent of disease transmission and population dynamics.     

教学相长:怎样做学术领导人

家世 我祖籍福建晋江,祖父陈廷虎是前清秀才,废科举后,习中医,育有六子。家父陈志英为么儿,七岁及十二岁时,先祖父和先祖母相继去世。家父曾在中药房当学徒,学记帐,后至马来西亚当锡矿及橡胶工人,幸得老板赏识,提拔为会计人员,方有时间自修读书。抗战前返福建,以同等学历在厦门集美师范及警官训练班受训。1939年与同为集美师范毕业之家母蔡玉洁结婚。外祖父蔡乙戎为基督教长老会牧师。我1940年出生于安溪。[编者按]     

Colicin S8 export: extracellular and cytoplasmic colicin are different

The properties of colicin S8 are different for the cytoplasmic, periplasmic and extracellular protein. Interactions with its specific receptors reflect this. Active cell extracts separate into a non-anionic along with an anionic fraction by DEAE-Sephacell chromatography. Previously, we have purified cell-associated colicin S8 as an aggregation of highly related polypeptides; cytoplasmic colicin S8 seems to be post-translationally processed into an aggregation of polypeptides of molecular mass ranging from 45,000 Da to 60,000 Da. We suggest that a conformational change to colicin S8 may occur related to the export process.     

Neuronal development: neighbors have to be different

The assembly of neurons into functional circuits requires a multitude of cellular recognition events. Recent work on the hypervariable Drosophila Dscam gene revealed how a vast number of cell adhesion proteins contributes to neuronal patterning.     

Farnesyl transferase inhibitors: one target may be found in another

The fact that proteins such as Ras require farnesylation to induce malignant transformation prompted many investigators to design farnesyl transferase inhibitors (FTI) as novel anticancer drugs. FTIs inhibit the growth of ras transformed cells in vitro and induce tumor regression in ras dependent tumor in vivo. Moreover, FTIs inhibit tumor progression in human tumor xenograft models. Currently, FTIs are undergoing phase I and II trials in various cancer types. They show impressive antitumour efficacy and they lack toxicity. Despite these promising results, the development of such molecules in hindered by the absence of appropriate clinical endpoints and of surrogate biological markers. Indeed, it seems likely that Ras is not the critical target of FTIs and that inhibition of the farnesylation of proteins such as RhoB, might also contribute to the observed antitumour properties. Identification of targets that underlie their biological effect is essential in order to predict and evaluate their efficacy.     

Individual recognition: it is good to be different

Individual recognition (IR) behavior has been widely studied, uncovering spectacular recognition abilities across a range of taxa and modalities. Most studies of IR focus on the recognizer (receiver). These studies typically explore whether a species is capable of IR, the cues that are used for recognition and the specializations that receivers use to facilitate recognition. However, relatively little research has explored the other half of the communication equation: the individual being recognized (signaler). Provided there is a benefit to being accurately identified, signalers are expected to actively broadcast their identity with distinctive cues. Considering the prevalence of IR, there are probably widespread benefits associated with distinctiveness. As a result, selection for traits that reveal individual identity might represent an important and underappreciated selective force contributing to the evolution and maintenance of genetic polymorphisms.