Smy2p participates in COPII vesicle formation through the interaction with Sec23p/Sec24p subcomplex

The coat protein complex II (COPII) is essential for vesicle formation from the endoplasmic reticulum (ER) and is composed of two heterodimeric subcomplexes, Sec23p/Sec24p and Sec13p/Sec31p, and the small guanosine triphosphatase Sar1p. In an effort to identify novel factors that may participate in COPII vesicle formation, we isolated SMY2 , a yeast gene encoding a protein of unknown function, as a multicopy suppressor of the temperature-sensitive sec24-20 mutant. We found that even a low-copy expression of SMY2 was sufficient for the suppression of the sec24-20 phenotypes, and the chromosomal deletion of SMY2 led to a severe growth defect in the sec24-20 background. In addition, SMY2 exhibited genetic interactions with several other genes involved in the ER-to-Golgi transport. Subcellular fractionation analysis showed that Smy2p was a peripheral membrane protein fractionating together with COPII components. However, Smy2p was not loaded onto COPII vesicles generated in vitro . Interestingly, coimmunoprecipitation between Smy2p and the Sec23p/Sec24p subcomplex was specifically observed in sec23-1 and sec24-20 backgrounds, suggesting that this interaction was a prerequisite for the suppression of the sec24-20 phenotypes by overexpression of SMY2 . We propose that Smy2p is located on the surface of the ER and facilitates COPII vesicle formation through the interaction with Sec23p/Sec24p subcomplex.     

Isolation and Characterization of the N-linked Oligosaccharides in Nacrein from <Emphasis Type="Italic">Pinctada fucata</Emphasis>

We analyzed the structure of the N-linked oligosaccharides enzymatically liberated from the organic matrix (OM) component in the nacreous layer of Japanese pearl oyster: Pinctada fucata. The lectin-blot analysis of the soluble OM after separation by SDS-PAGE, four components, with sizes of approximately 55 kDa, 35 kDa, 25 kDa, and 21 kDa were detected with GNA lectin, which recognized terminal mannose of high mannose and hybrid types of N-glycan. The 55-kDa component of the soluble OM detected by lectin blotting was identified as nacrein by using liquid chromatography/mass spectrometry (LC/MS). LC/MS analysis of the N-glycan liberated from nacrein detected a hybrid-type N-glycan, which contained sulfite and sialic acid at its terminus. The data strongly imply that nacrein, a sulfated OM glycoprotein, participates in molluscan biomineralization by creating a favorable environment for calcium ion uptake through sulfonic acid and sialic acid.     

Longitudinal changes in zooplankton distribution below a reservoir outfall with reference to river planktivory

The fate and interactions with river organisms of zooplankton as they drift downriver from a reservoir on a fourth-order mountain stream (Hiji River, Japan) were investigated. Monthly samples were collected at the reservoir and six river sites, simultaneously, from May 2005 to May 2006. Aquatic macroinvertebrates and fish were colleted, and their stomach contents were analyzed in April and May, 2006, respectively. Drift from the reservoir was the primary source for the river plankton community; the abundance of zooplankton, particularly those of cladocerans and large rotifer, rapidly decreased within several kilometers of the dam. Analysis of the contents of fish stomachs showed that drifting zooplankton was the main food for fish, with strong food selectivity for cladocerans and large rotifers. However, fish and insect planktivores showed longitudinally different stomach contents, with progressively fewer zooplankton found in the stomachs at the downriver sites. The results suggest that the outflow of zooplankton from the reservoir is an important food source for the downstream predators, especially fish, but the drift of zooplankton and consequent food availability for the predators at lower sites are strongly limited by concentrated fish predation just below the reservoir dam.     

Estimating species richness and catch per unit effort from boat electro‐fishing in a lowland river in temperate Australia

Abstract Biodiversity estimates are typically a function of sampling effort and in this regard it is important to develop an understanding of taxon‐specific sampling requirements. Northern hemisphere studies have shown that estimates of riverine fish diversity are related to sampling effort, but such studies are lacking in the southern hemisphere. We used a dataset obtained from boat electro‐fishing the fish community along an essentially continuous 13‐km reach of the Murrumbidgee River, Australia, to investigate sampling effort effects on fish diversity estimates. This represents the first attempt to investigate relationships between sampling effort and the detection of fish species in a large lowland river in Australia. Seven species were recorded. Species‐specific patterns in catch per unit effort were evident and are discussed in terms of solitary and gregarious species, recreational fishing and the monitoring of rare and threatened species. There was a requirement to sample substantial lengths of river to describe total species richness of the fish community in this river reach. To this end, randomly allocated sampling effort and use of species richness estimators produced accurate estimates of species richness without the requirement for excessive levels of effort. Twenty operations were required to estimate species richness at this site, highlighting the need for comparable studies of river fish communities in lowland rivers elsewhere in Australia and the southern hemisphere.     

一年生野生大豆根系及胚轴皮层通气组织发育观察

用石蜡切片法对一年生野生大豆(Glycine sojaSieb.et Zucc.)的通气组织发育过程进行观测研究,以探讨其耐湿机制.研究表明:(1)在正常生长条件下,一年生野生大豆播种3~5周后主根开始形成皮层通气组织,经过2周左右基本形成根系与茎贯通的通气道;皮层通气组织首先在根茎连接点上下开始形成,再向根尖方向和茎扩展.(2)来自不同生态环境的一年生野生大豆开始形成皮层通气组织的部位相同,但开始产生通气组织的时间存在差异.     

Genetic relatedness in early associations of Polistes dominulus: from related to unrelated helpers

Indirect benefits obtained through the reproduction of relatives are fundamental in the formation and maintenance of groups. Here, we examine the hypothesis that females of the temperate paper wasp Polistes dominulus preferentially form groups with close relatives. Genetic relatedness data were obtained for 180 groups of females collected at the early stages of the nesting cycle of a large population of P. dominulus in two sites in southwestern Spain. Average within-group relatedness values ranged from 0.189 to 0.491. Foundresses on early nests were significantly more closely related than females in winter aggregations or in stable groups (just before workers emerged). Within-group relatedness values were independent of group size. The vast majority of worker-producing nests ( c . 85%) had one or more females that were unrelated (or distantly related) to the remaining members of the group. These results provide further support to the hypothesis that indirect fitness benefits alone are unlikely to explain why P. dominulus foundresses form cooperative associations.     

Introduction. Calcium signals and developmental patterning

Calcium ions generate ubiquitous cellular signals. Calcium signals play an important role in development. The most obvious example is fertilization, where calcium signals and calcium waves are triggered by the sperm and are responsible for activating the egg from dormancy and cell cycle arrest. Calcium signals also appear to contribute to cell cycle progression during the rapid cell cycles of early embryos. There is increasing evidence that calcium signals are an essential component of the signalling systems that specify developmental patterning and cell fate. This issue arises from a Discussion Meeting that brought together developmental biologists studying calcium signals with those looking at other patterning signals and events. This short introduction provides some background to the papers in this issue, setting out the emerging view that calcium signals are central to dorsoventral axis formation, gastrulation movements, neural specification and neuronal cell fate.     

Analysis of severe acute respiratory syndrome coronavirus structural proteins in virus‐like particle assembly

SARS‐CoV has four major structural proteins: the N, S, M, and E proteins. To investigate the mechanism of SARS‐CoV assembly, we cloned the genes encoding these four proteins into the eukaryotic expression vector pCAGGS and transfected them into 293T cells. When all four expression vectors were co‐transfected VLP formed, as confirmed using electron microscopy. Using a rabbit polyclonal antibody specific to the N protein, N‐protein‐containing particles similar in size to the VLP were also observed by immunoelectron microscopy, indicating that the VLP contained the N protein. Co‐immunoprecipitation analyses demonstrated an interaction between the N and M proteins, suggesting that N protein binds directly to M protein to be incorporated into VLP.     

Comparative digestion studies in wild suids at Rotterdam Zoo

Among the artiodactyla, the suids are a group whose digestive physiology has hardly been investigated. The apparent digestibilities (aD) of macronutrients were measured in captive specimens of warthog (Phacochoerus africanus), red river hog (Potamochoerus porcus), and Visayan warty pigs (Sus cebifrons), and compared with those reported for babirusa (Babyrousa babyrussa) from the same facility on a similar diet. The animals were fed mixed diets of pelleted feed, grains, fruits, and vegetables; dietary neutral detergent fiber (NDF) ranged from 17 to 26% dry matter. aD of organic matter and protein ranged from 72 to 89 and 70 to 82%, respectively. Although red river hogs and warty pigs achieved aD of NDF of 41–54%, this value was higher both in warthogs (63–66%) and babirusa (61–63%). aD of acid detergent fiber was comparatively low in red river hogs (4%), warty pigs (22%), and babirusa (13–25%) but high in warthog (59–62%). Comparison with additional literature data (including peccaries) indicates that in spite of differences in digestive anatomy, suids and peccaries are similar, and resemble other herbivores in fundamental characteristics, such as the negative influence of fiber on overall digestibility, or the positive influence of dietary protein on protein digestion. Although the existing data are equivocal as to a superior fiber digestion in peccaries as compared with other wild suids, the results suggest that warthogs are more efficient than other wild suids or peccaries in terms of fiber digestion. Zoo Biol 27:305–319, 2008. © 2008 Wiley‐Liss, Inc.     

The solitary (primary) cilium--a mechanosensory toggle switch in bone and cartilage cells

Osteocytes and articular chondrocytes sense and respond to the strains imposed on bones and joints by various activities such as breathing and walking. This mechanoresponsiveness is needed to maintain bone and cartilage microstructure and strength. In bone the large number of osteocytes form a vast osteointernet in which the gap junctionally interconnected members are lodged in an extensive lacunocanalicular network. The much smaller number of articular chondrocytes are not interconnected in a chondrointernet. Instead, they are separately lodged in capsules called chondrons. While there are many possible strain-sensing devices, it now appears that the non-motile solitary (primary) cilia protruding like aerials from osteocytes (as well as osteoblasts) and chondrocytes are switches that when toggled by cyclical pulses of lacunocanalicular fluid or cartilage compression send signals such as Ca²⁺ surges into the cell to trigger a cascade of events that include appropriate gene activations to maintain and strengthen bone and cartilage. Moreover, the chondrocyte cilium with its Ihh(Indian hedgehog)-activated Smo receptor is a key player along with PTHrP in endochondral bone formation.