Pectic homogalacturonan masks abundant sets of xyloglucan epitopes in plant cell walls

Background  

Molecular probes are required to detect cell wall polymers in-situ to aid understanding of their cell biology and several studies have shown that cell wall epitopes have restricted occurrences across sections of plant organs indicating that cell wall structure is highly developmentally regulated. Xyloglucan is the major hemicellulose or cross-linking glycan of the primary cell walls of dicotyledons although little is known of its occurrence or functions in relation to cell development and cell wall microstructure.     

Chick embryo chorioallantoic membrane (CAM): an alternative predictive model in acute toxicological studies for anti-cancer drugs

The chick embryo chorioallantoic membrane (CAM) is a preclinical model widely used forvascular and anti-vascular effects of therapeutic agents in vivo. In thisstudy, we examine the suitability of CAM as a predictive model for acute toxicologystudies of drugs by comparing it to conventional mouse and rat models for 10 FDA-approvedanticancer drugs (paclitaxel, carmustine, camptothecin, cyclophosphamide, vincristine,cisplatin, aloin, mitomycin C, actinomycin-D, melphalan). Suitable formulations forintravenous administration were determined before the average of median lethal dose(LD₅₀) and median survival dose (SD₅₀) in the CAM were measuredand calculated for these drugs. The resultant ideal LD₅₀ values were correlatedto those reported in the literature using Pearson’s correlation test for both intravenousand intraperitoneal routes of injection in rodents. Our results showed moderatecorrelations (r²=0.42 − 0.68, P<0.005–0.05) between theideal LD₅₀ values obtained using the CAM model with LD₅₀ values frommice and rats models for both intravenous and intraperitoneal administrations, suggestingthat the chick embryo may be a suitable alternative model for acute drug toxicityscreening before embarking on full toxicological investigations in rodents in developmentof anticancer drugs.     

Correlations between genetic variance and adiposity measures,and gene × gene interactions for obesity in postmenopausal Vietnamese women

Although environmental factors are important, there is considerable evidence that genes also have a significant role in the pathogenesis of obesity. We conducted a population-based study to investigate the relationship between candidate genes for obesity (UCP1, UCP2, ADRA2B, ADRB3, LEPR, VDR and ESR1) and adiposity measures (body mass index, body fat percentage, weight, waist circumference and waist–hip ratio) in terms of individual gene and gene × gene interaction in models unadjusted and adjusted for covariates (age, years since menopause, educational level and total energy intake). Postmenopausal women with TC genotype of ESR1 gene had higher body fat percentage than those with TT genotype in the models unadjusted and adjusted for the covariates (P = 0.006 in adjusted model). In multiple logistic regression analysis, BsmI and ApaI SNPs of VDR genes were significantly associated with overweight and obesity. The UCP2–VDR ApaI interaction to susceptibility of overweight and obesity was first observed from logistic regression analysis, and then confirmed in the multifactor dimensionality reduction method unadjusted and adjusted for the covariates. This interaction had 69.09% prediction accuracy for overweight and obesity (P = 0.001, sign test). In conclusion, the study suggests the significant association of ESR1 and VDR genes with adiposity measures and the UCP2–VDR ApaI interaction to susceptibility to being overweight and obesity in postmenopausal Vietnamese women.     

Cloning and sequencing of mouse GABA transporter complementary DNA

A cDNA encoding the mouse GABA transporter has been isolated and sequenced.The results show that the mouse GABA transporter cDNA differs from that of the rat by 60 base pairs at the open reading frame region but the deduced amino acid sequences of the two cDNAs are identical and both composed of 599 amino acids.However,the amino acid sequence is different from the sequence deduced from a recently published mouse GABA transporter cDNA.     

Differential Cell Cohesiveness Expressed by Prespore and Prestalk Cells of Dictyostelium discoideum

Pseudoplasmodia of Dictyostelium discoideum at the culmination stage were separated into two cell populations by sedimentation in a discontinuous renografin gradient. The two lighter fractions (I and II) had enzymatic activities characteristic of the anterior prestalk cells, while the heaviest fraction (III) showed enzyme activities characteristic of the posterior prespore cells. Cell-cell adhesion among prespore cells is much more resistant to EDTA dissociation than 10-h cells and prestalk cells. Fab fragments prepared from antibodies directed against a specific cell surface glycoprotein gp150 were more effective in dissociating prespore cells than prestalk cells. In addition, prespore cells contained an approximately 2-fold higher concentration of the endogenous carbohydrate binding protein discoidin-I than prestalk cells. These differences may account for the differential cohesiveness of these two cell populations and provide a basis for cell recognition and cell sorting at the slug stage.     

Molecular cloning and structural analysis of human norepinephrine transporter gene（NETHG）

A cDNA molecule encoding a major part of the human Norepinephrine transporter(hNET) was synthesized by means of Polymerase Chain Reaction(PCR) technique and used as a probe for selecting the human genomic NET gene.A positive clone harbouring the whole gene was obtained from a human lymphocyte genomic library through utilizing the “genomic walking” technique.The clone,designated as phNET,harbours a DNA fragment of about 59 kd in length inserted into BamH I site in cosmid pWE15.The genomic clone contains 14 exons encoding all amino acid residues in the protein.A single exon encodes a distinct transmembrane domain,except for transmembrane domain 10 and 11,which are encoded by part of two exons respectively,and exon 12,which encodes part of domain 11 and all of domain 12.These results imply that there is a close relationship between exon splicing of a gene and structureal domains of the protein,as is the case for the human γ－aminobutyric acid transporter(hGAT) and a number of other membrane proteins.     

Expression of an apoplast‐localized BURP‐domain protein from soybean (GmRD22) enhances tolerance towards abiotic stress

The BURP‐domain protein family comprises a diverse group of plant‐specific proteins that share a conserved BURP domain at the C terminus. However, there have been only limited studies on the functions and subcellular localization of these proteins. Members of the RD22‐like subfamily are postulated to associate with stress responses due to the stress‐inducible nature of some RD22‐like genes. In this report, we used different transgenic systems (cells and in planta) to show that the expression of a stress‐inducible RD22‐like protein from soybean (GmRD22) can alleviate salinity and osmotic stress. We also performed detailed microscopic studies using both fusion proteins and immuno‐electron microscopic techniques to demonstrate the apoplast localization of GmRD22, for which the BURP domain is a critical determinant of the subcellular localization. The apoplastic GmRD22 interacts with a cell wall peroxidase and the ectopic expression of GmRD22 in both transgenic Arabidopsis thaliana and transgenic rice resulted in increased lignin production when subjected to salinity stress. It is possible that GmRD22 regulates cell wall peroxidases and hence strengthens cell wall integrity under such stress conditions.     

INTERPOPULATION VARIATION IN JUVENILE SURVIVAL AND GROWTH RATES OF LYMNAEA PEREGRA (GASTROPODA: PULMONATA); TEMPERATURE AT RECRUITMENT AS A SELECTION PRESSURE?

Three neighbouring populations of Lymnaea peregra had recruitmentin the summer (June and July), but one population (Sheaf) hada second recruitment in September and October. We hypothesizedthat juveniles of the Sheaf population would be subject to selectionunder both ‘summer’ and ‘winter’ conditions,and thus should be more resistant to low-temperature stressthan juveniles of the other populations. The hypothesis wassupported by the findings that Sheaf juveniles survived andgrew better over a wider range of temperatures (2, 10, 15 and20°C )while juveniles of the other two populations wereadapted only to higher temperatures (15 and 20°C). Therewas evidence that some of these traits were genetically fixed. ^*Present address: Department of Applied Science, City Polytechnicof Hong Kong, Mongkok, Kowloon, Hong Kong. (Received 15 September 1988; accepted 16 December 1988)