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131.
Abnormal placentation results in either inadequate (consequences: recurrent miscarriage, intrauterine growth restriction, and preeclampsia) or overzealous (consequences: placenta accreta, increta, and percreta) placentation. NK cells dominate in first trimester decidua and probably control extravillous cytotrophoblast (EVT) invasion. We examined this interaction in a novel way, using NK cells and villous explants from concordant first trimester pregnancies cocultured using a new collagen (two-dimensional) model of placentation. Decidual NK (dNK) cells exerted contact-independent inhibition of normal cytotrophoblast migration, associated with changes in the cytotrophoblast expression of metalloproteases-2 and -9, and plasminogen activator inhibitor-1. dNK cells did not affect EVT proliferation and apoptosis, and cell column formation. dNK cell effects were partially reversed by neutralizing Abs against IFN-gamma. We provide ex vivo human evidence of a direct role for dNK in modulating EVT differentiation as they form columns and then migrate from anchoring villi.  相似文献   
132.
The average height of 31-aged Robinia pseudoacacia plantation in west mountain of Beijing is 7 in and the mean breastheight diameter of tree is 8.3 cm. The number of tree per hectare appears 1750. The canopy coverage of plantation shows 0.5. Using tile diameter square at tree breast height times tree height (D2H), as an independing variable, to estimate the dry weight of various parts of trees, between them the significient correlations occur. According to the modle of Wstem=58.88(D2H)0.88 (WBranch)=e7.77+0.001(D2H) (Wleaf)=e5.71+0.0008(D2H) (Wroot)=e7.67+0.0009(D2H) 28.45 t/ha of the stem biomass, 11.6 t/ha of the branch biomass. 0.97 t/ha of the leaf biomass, 7.6 t/ha of the root biomass are estimated in arbor layer. The aboveground and belowground biomass of shrub and herb layers axe 13.71 t/ha and 10.72 t/ha respectively in September, the biomass of shrub and herb layer is 24.43 t/ha. 73.05 t/ha of the total biomass in Robinia pseudoacacia plantation is obtained.  相似文献   
133.
The issue of amino acid depth in proteins gives important insights to our understanding of protein’s three-dimensional structure. There has already been much research done in mathematical and statistical sciences regarding the general definitions, properties and algorithms describing the particle depth of spatially extended systems. We constructed a method of calculating the amino acids depths and applied it to a set of 527 protein structures. We propose the introduction of amino acid depth tendency factors for three-dimensional structures of proteins. The depth tendency factors relate not only to the hydrophobicity indices but also to the electrostatic charge. We found a relationship between the protein size and the number of residues using the distance between the deepest residue and surface residues. We made a prediction regarding the number of residues on the surface of a protein, the deepest amino acid, and the average depth, all of which are fitted well to a linear functional relationship with the length of the protein. Finally, we have predicted the depths of multiple peptides in protein’s three-dimension structure. Electronic supplementary material The online version of this article () contains supplementary material, which is available to authorized users.  相似文献   
134.
The rates of canopy apparent photosynthesis (PC) and canopy respiration (Rc) were studied during vegetation season in two erectophile and two planophile hybrids of maize (Zea mays L.) grown at two canopy densities [7.5 plants m-2 (HD) and 4.5 plants m-2 (LD)]. Large differences in PC, Rc, RC/PC, leaf area index (LAI), dry matter accumulation and grain yield were found among hybrids and plant densities. Variations in PC and RC were associated mainly with changes in LAI. There was also found change in PC per unit LAI with time. The average RC/PC was 28.9 % for all treatments throughout the vegetation season. PC and RC per unit dry matter were higher in LD than in HD and decreased throughout the measurement period. The HD stand had higher PC and yield in hybrids with erectophile foliage, whereas LD stand had higher PC after male tetrad and got higher yield in hybrids with planophile foliage. Only RC in hybrids of the two foliage types was higher under HD than under LD throughout the vegetation period.  相似文献   
135.
A novel, cold-active and highly alkaliphilic esterase was isolated from an Antarctic desert soil metagenomic library by functional screening. The 1,044 bp gene sequence contained several conserved regions common to lipases/esterases, but lacked clear classification based on sequence analysis alone. Moderate (<40%) amino acid sequence similarity to known esterases was apparent (the closest neighbour being a hypothetical protein from Chitinophaga pinensis), despite phylogenetic distance to many of the lipolytic “families”. The enzyme functionally demonstrated activity towards shorter chain p-nitrophenyl esters with the optimal activity recorded towards p-nitrophenyl propionate (C3). The enzyme possessed an apparent Topt at 20°C and a pH optimum at pH 11. Esterases possessing such extreme alkaliphily are rare and so this enzyme represents an intriguing novel locus in protein sequence space. A metagenomic approach has been shown, in this case, to yield an enzyme with quite different sequential/structural properties to known lipases. It serves as an excellent candidate for analysis of the molecular mechanisms responsible for both cold and alkaline activity and novel structure–function relationships of esterase activity.  相似文献   
136.

Publisher's Note

Addition to Special Issue “Transient interactions in biology”  相似文献   
137.
In this study, the non-target effects of Bt rice “KMD2” expressing a Cry1Ab protein on the performance of the brown planthopper (BPH), Nilaparvata lugens, over multiple generations were evaluated under laboratory and field conditions. In the laboratory, BPH was reared to observe the impact of the Bt rice as compared to its parental non-Bt cultivar Xiushui 11, while the population dynamics and oviposition performance of BPH were investigated in the field. The survival of BPH nymphs fed Bt and non-Bt rice did not differ significantly. The nymph developmental duration of BPH was significantly delayed by the Bt rice by comparison with the non-Bt rice for the 1st and 2nd but not the 4th generation. Most importantly, the fecundity of BPH on the Bt rice was significantly decreased in every generation when compared with the non-Bt rice. In the field investigations, the population density of BPH nymphs was significantly lower in the Bt rice field. However, the temporal pattern of population dynamics of BPH adults was similar between the Bt and non-Bt rice, presumably due to migratory interference of the adults. In the Bt rice field, the percentage of tillers with eggs and the number of eggs per tiller were also significantly lower from tillering to mature stage. Additionally, Cry1Ab protein could not be detected in guts from single BPH adults. In general, our results suggest that the Bt rice “KMD2” could not stimulate an outbreak of BPH.  相似文献   
138.
欧阳相 《蛇志》1991,3(3):8-9
本文报告尖吻蝮咬伤并心脏受累20例。经中西医结合治愈19例(95%),死亡1例(5%),并对其发病机理及治疗进行了讨论。  相似文献   
139.
In order to avoid interference from nuclear copies of mitochondrial DNA (numts), mtDNA of the white Roman goose (domestic goose) was extracted from liver mitochondria. The mtDNA control region was amplified using a long PCR strategy and then sequenced. Neighbor-joining, maximum parsimony, and maximum-likelihood approaches were implemented using the 1,177 bp mtDNA control region sequences to compute the phylogenetic relationships of the domestic goose with other geese. The resulting identity values for the white Roman geese were 99.1% (1,166/1,177) with western graylag geese and 98.8% (1,163/1,177) with eastern graylag geese. In molecular phylogenetic trees, the white Roman goose was grouped in the graylag lineage, indicating that the white Roman goose came from the graylag goose (Anser anser). Thus, the scientific name of the white Roman goose should be Anser anser ‘White Roman.’  相似文献   
140.
Leaf morphology is an important agronomic trait in rice breeding. We isolated three allelic mutants of NARROW AND ROLLED LEAF 1 (nrl1) which showed phenotypes of reduced leaf width and semi-rolled leaves and different degrees of dwarfism. Microscopic analysis indicated that the nrl1-1 mutant had fewer longitudinal veins and smaller adaxial bulliform cells compared with the wild-type. The NRL1 gene was mapped to the chromosome 12 and encodes the cellulose synthase-like protein D4 (OsCslD4). Sequence analyses revealed single base substitutions in the three allelic mutants. Genetic complementation and over-expression of the OsCslD4 gene confirmed the identity of NRL1. The gene was expressed in all tested organs of rice at the heading stage and expression level was higher in vigorously growing organs, such as roots, sheaths and panicles than in elsewhere. In the mutant leaves, however, the expression level was lower than that in the wild-type. We conclude that OsCslD4 encoded by NRL1 plays a critical role in leaf morphogenesis and vegetative development in rice.  相似文献   
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