Structural insights into the membrane microdomain organization by SPFH family proteins

The lateral segregation of membrane constituents into functional microdomains,conceptually known as lipid raft,is a universal organization principle for cellula...     

Onshore–offshore variations of copepod community in northern South China Sea

Previous studies which have tested the feeding preferences of shredders for fungal species and the food quality of fungi used detritus uniformly colonized by a fungus, which is not the case for decaying leaves in streams. It is not known whether shredders in different development stages exhibit variations in feeding preference and larval performance. This study examined the feeding preferences and the growth of the third and the fifth instars of Pycnopsyche gentilis larvae using fungal-colonized patches and whole leaves, respectively, having different fungal species compositions (Alatospora acuminata, Anguillospora filiformis, Articulospora tetracladia, Tetrachaetum elegans, and all species combined). The aquatic hyphomycetes used were co-dominant on leaves in the stream inhabited by the caddisfly. During 14 d of feeding, the larvae of both instars did not show significant differences in feeding preferences for the patches growing on oak leaves, although the third instar larvae were slightly more selective than the fifth instar larvae. When fed with maple leaves for 18 d, larval growth rates, gross growth efficiencies, and survivorship were not significantly different among the fungal treatments. However, the larval growth of both instars fed with fungal-colonized leaves was always significantly greater than the growth of larvae fed with diets of uncolonized leaves. The third instar larvae grew faster than the fifth instar larvae, but the growth efficiencies of the two instars were similar. These results suggest that P. gentilis larvae exhibit less selectivity in their feeding than other caddisfly shredders that have been examined and that the dominant fungi colonizing leaves in their habitat are similar in palatability and food quality for this shredder. Handling editor: B. Oertli     

Interaction of sortase A and lipase 2 in the inhibition of <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> biofilm formation

Recombinant sortase A (SrtA) was used to immune rabbit, and the inhibitory activity of anti-SrtA serum on Staphylococcus aureus biofilm formation was tested. Biofilm formation was inhibited by anti-SrtA rabbit serum in S. aureus ATCC25923 and two clinical isolated strains. The antiserum was separated into two fractions, and the main component with the inhibitory activity was demonstrated to be the IgG fraction. Two proteins interact with the IgG fraction were identified by using an in vitro pull-down assay and were confirmed to be lipase 2 and γ-hemolysin by mass spectrometry. Cross-interaction between SrtA and lipase 2 was further confirmed by Western blotting. Addition of anti-lipase 2 serum in the culture medium also showed inhibitory effect against biofilm formation. Together, our study suggests anti-SrtA serum inhibits S. aureus biofilm formation and lipase 2 is one of the targets of anti-SrtA serum in this inhibition process. This is the first study to demonstrate the roles of antisera against SrtA and lipase 2 in the inhibition of biofilm formation in S. aureus.     

免疫荧光染色检测克隆牛X染色体组蛋白H3 Lys 4 二甲基化修饰

利用免疫荧光染色, 检测胎儿成纤维细胞(FFB)和输卵管上皮细胞(FOV)来源的克隆牛X中期染色体组蛋白H3 K4m2修饰状况。结果发现, 这两种细胞系来源的克隆牛耳组织细胞系X染色体H3 K4m2修饰与供体核FFB细胞系和常规繁殖牛耳组织细胞系的修饰基本一致, 而与供体核FOV细胞系有较大差异。     

DNA methylation changes in cell line from beta-lactoglobulin gene targeted fetus

The gene targeting combined somatic cell nuclear transfer is very useful in agriculture and medicine. Epigenetic modification of DNA by methylation is significant in regulating gene expression during mammalian development. During gene targeting, epigenetic status of donor cell nuclei may be changed in a series of processes, including homologous recombination, cell selection and cloning. We examined DNA methylation of six genes (beta-actin, VEGF, oct4, TERT, H19 and Igf2) and a repetitive sequence art2 in blg(+/-) cell line from beta-lactoglobulin (BLG) gene targeted fetus and the cells used for BLG gene targeting serve as control. The results demonstrated that the widespread changes of DNA methylation were found in blg(+/-) cell line. But the degree of variation was different. DNA methylation of VEGF in blg(+/-) was noticeably decreased. These observations suggest that DNA methylation variations may impact gene expression and finally induce abnormalities and lethality in later developmental stages.     

XC1028 from Xanthomonas campestris adopts a PilZ domain‐like structure without a c‐di‐GMP switch

The crystal structure of XC1028 from Xanthomonas campestris has been determined to a resolution of 2.15 Å using the multiple anomalous dispersion approach. It bears significant sequence identity and similarity values of 64.10% and 70.09%, respectively, with PA2960, a protein indispensable for type IV pilus‐mediated twitching motility, after which the PilZ motif was first named. However, both XC1028 and PA2960 lack detectable c‐di‐GMP binding capability. Although XC1028 adopts a structure comprising a five‐stranded β‐barrel core similar to other canonical PilZ domains with robust c‐di‐GMP binding ability, considerable differences are observed in the N‐terminal motif; XC1028 assumes a compact five‐stranded β‐barrel without an extra long N‐terminal motif, whereas other canonical PilZ domains contain a long N‐terminal sequence embedded with an essential “c‐di‐GMP switch” motif. In addition, a β‐strand (β1) in the N‐terminal motif, running in exactly opposite polarity to that of XC1028, is found inserted into the parallel β3/β1′ strands, forming a completely antiparallel β4↓β3↑β1↓β1′↑ sheet in the canonical PilZ domains. Such dramatic structural differences at the N‐terminus may account for the diminished c‐di‐GMP binding capability of XC1028, and suggest that interactions with additional proteins are necessary to bind c‐di‐GMP for type IV fimbriae assembly. Proteins 2009. © 2008 Wiley‐Liss, Inc.     

Current status and future prospects of Zoige Marsh in Eastern Qinghai-Tibet Plateau

Zoige Marsh, located in the Northeastern Qianghai-Tibet Plateau, is the largest highland marsh in the world. The marsh is one of the hotspots for biodiversity, harboring many endemic and endangered species, including Grus nigricollis, the only plateau crane. Zoige Marsh has a large area of high-quality grasslands, serving as the fifth largest livestock base in China, and it is also the major water source to the headstream of the Yellow River. However, due to global warming and unwise use of the marsh resources, including ditching for grassland enlargement, peat exploitation, and livestock grazing, since the 1970s, Zoige Marsh has suffered severe ecosystem degradations such as vegetation recessive succession, biodiversity loss, soil deterioration, and rodent disasters. It is therefore imperative to restore the damaged marsh. We propose in this paper that ecological engineering and livestock population control must be taken as measures for ecological restoration and biodiversity protection.     

Ectopic expression of S-RNase of <Emphasis Type="Italic">Petunia inflata</Emphasis> in pollen results in its sequestration and non-cytotoxic function

The specificity of S-RNase-based self-incompatibility (SI) is controlled by two S-locus genes, the pistil S-RNase gene and the pollen S-locus-F-box gene. S-RNase is synthesized in the transmitting cell; its signal peptide is cleaved off during secretion into the transmitting tract; and the mature “S-RNase”, the subject of this study, is taken up by growing pollen tubes via an as-yet unknown mechanism. Upon uptake, S-RNase is sequestered in a vacuolar compartment in both non-self (compatible) and self (incompatible) pollen tubes, and the subsequent disruption of this compartment in incompatible pollen tubes correlates with the onset of the SI response. How the S-RNase-containing compartment is specifically disrupted in incompatible pollen tubes, however, is unknown. Here, we circumvented the uptake step of S-RNase by directly expressing S₂-RNase, S₃-RNase and non-glycosylated S₃-RNase of Petunia inflata, with green fluorescent protein (GFP) fused at the C-terminus of each protein, in self (incompatible) and non-self (compatible) pollen of transgenic plants. We found that none of these ectopically expressed S-RNases affected the viability or the SI behavior of their self or non-self-pollen/pollen tubes. Based on GFP fluorescence of in vitro-germinated pollen tubes, all were sequestered in both self and non-self-pollen tubes. Moreover, the S-RNase-containing compartment was dynamic in living pollen tubes, with movement dependent on the actin–myosin-based molecular motor system. All these results suggest that glycosylation is not required for sequestration of S-RNase expressed in pollen tubes, and that the cytosol of pollen is the site of the cytotoxic action of S-RNase in SI.