血管内皮祖细胞与糖尿病微血管病变研究进展

糖尿病微血管病变严重影响了患者生活质量,是患者致死致残主要原因。微血管病变主要表现在视网膜、肾、神经、心肌组织。微血管病变的机制尚未完全清楚,近年越来越多研究发现血管内皮祖细胞(endothelial progenitor cells,EPCs)是该病发病重要原因。EPCs有分化为成熟的内皮细胞并且参与新血管形成和新生的能力。正常情况下内皮损失和EPCs对内皮的修复作用处于动态平衡状态,一旦EPCs受损,内皮损害和修复之间的平衡被打破,内皮层的完整性遭到破坏,必然参与糖尿病血管病变的发生发展。国内外大量研究证明糖尿病合并大血管病变EPCs数目功能改变,而糖尿病合并微血管病变EPCs的怎样变化?本文就EPCs与糖尿病微血管病变的关系进行系统综述。     

Complementation of a Nonmotile flaB Mutant of Borrelia burgdorferi by Chromosomal Integration of a Plasmid Containing a Wild-Type flaB Allele

With the recent identification of antibiotic resistance phenotypes, the use of reporter genes, the isolation of null mutants by insertional inactivation, and the development of extrachromosomal cloning vectors, genetic analysis of Borrelia burgdorferi is becoming a reality. A previously described nonmotile, rod-shaped, kanamycin-resistant B. burgdorferi flaB::Km null mutant was complemented by electroporation with the erythromycin resistance plasmid pED3 (a pGK12 derivative) containing the wild-type flaB sequence and 366 bp upstream from its initiation codon. The resulting MS17 clone possessed erythromycin and kanamycin resistance, flat-wave morphology, and microscopic and macroscopic motility. Several other electroporations with plasmids containing wild-type flaB and various lengths (198, 366, or 762 bp) of sequence upstream from the flaB gene starting codon did not lead to functional restoration of the nonmotile flaB null mutant. DNA hybridization, PCR analysis, and sequencing indicated that the wild-type flaB gene in nonmotile clones was present in the introduced extrachromosomal plasmids, while the motile MS17 clone was a merodiploid containing single tandem chromosomal copies of mutated flaB::Km and wild-type flaB with a 366-bp sequence upstream from its starting codon. Complementation was thus achieved only when wild-type flaB was inserted into the borrelial chromosome. Several possible mechanisms for the failure of complementation for extrachromosomally located flaB are discussed.     

Characterization of Spanish grapevine cultivar diversity using sequence-tagged microsatellite site markers.

A broad germplasm bank collection containing most of the autochthonous Spanish grapevine cultivars was analyzed using six sequence-tagged microsatellite site (STMS) loci: VVS2, VVMD5, VVMD7, ssrVrZAG47, ssrVrZAG62, and ssrVrZAG79. The number of alleles obtained ranged from 9 in ssrVrZAG47 to 13 in VVS2, and the observed genotypes per locus varied between 24 (ssrVrZAG47) and 41 (VVSS2). A total of 57 unique genotypes were obtained considering all 6 loci, and 40 varieties presented at least 1 of these specific genotypes. The genotypic combinations for the 6 loci have generated 163 different profiles in the 176 cultivars. Ten pairs of accessions and one group of four Garnacha's cultivars can not be differentiated. The observed heterozygosity varied between 75.6 (VVMD7) and 90.9% (VVMD5), without significant differences from the expected values for any loci. The VVMD5 locus was the most informative, and also showed the highest discrimination power. The cumulative discrimination power for all six loci was practically 1; however, in fact, these STMS loci have differentiated only about 93% of the accessions, probably owing to high relatedness of the plant material. Usefulness of this STMS set for characterization of a Spanish grapevine collection is emphasized, as well as the elaboration of databases with these molecular markers.     

Diversity in soil fungi from undisturbed and disturbed Celtis tala and Scutia buxifolia forests in the eastern Buenos Aires province (Argentina)

The rhizospheric soil microfungi from a native forest (undisturbed and disturbed) were studied using soil dilution plate and soil washing methods. Fungi were isolated using slightly acid and alkaline culture media. 54 taxa were isolated: 49 from undisturbed forest soil and 37 from disturbed forest soil. Acremonium sp., Aspergillus ustus, Coemansia pectinata, Doratomyces stemonitis, Fusarium solani, F. oxysporum, Gliocladium roseum, Humicola fusco-atra, Mortierella sp., Penicillium lilacinum, Trichoderma harzianum, and T. koningii, showed the highest frequency, in both, undisturbed and disturbed forests. In undisturbed soil forest the biodiversity index was 3.97 whereas in disturbed ones was 3.89.     

Digestive proteases during development of larvae of red palm weevil, Rhynchophorus ferrugineus (Olivier, 1790) (Coleoptera: Curculionidae).

The evolution of digestive proteases during larval development of Rhynchophorus ferrugineus (Olivier, 1790) has been studied. A progressive increase of protease activity has been found. The optimum pH for proteolytic activity against azocasein was determined. Caseinograms revealed an active complex of alkaline proteases from the early stages of the development. From the apparent molecular masses, three groups of proteases have been found - high molecular-mass proteases, medium molecular-mass proteases, and low molecular-mass proteases. Studies using specific protease inhibitors showed the major presence of serine proteases in gut extracts. The results obtained from larvae reared on different substrates have made possible a comparative assessment of the influence of diet on the development of the digestive enzymatic system. Larvae fed on an artificial diet showed a complete pattern of digestive proteases. Data suggest that this diet seems to be suitable for future research with this insect pest.     

Extracellular lipolytic activity in Phoma glomerata

Several properties of the lipolytic activity exhibited by the conidial fungus Phoma glomerata were studied. Lipolytic activity in an aqueous buffer medium was measured on triacylglycerol, phosphoglyceride and cholesterol ester under different experimental conditions. The effect of storage temperature on the stability of the hydrolytic activity, and optimal conditions of temperature and time of maximal activity were determined. The optimal conditions for maximal lipolytic activity were found to be 40–50 °C and 1 h. The activity released to the medium by 1 mg cells for 1 h at 40 °C was stated as the enzyme released unit (ERU). The protein fraction of MW > 50 kDa obtained by ultrafiltration of the medium, was active on the three substrates assayed, and it showed a non-specific hydrolytic activity on both the 1- and 2-acyl esters either in the neutral glyceride or in the phosphoglyceride. A protein of M _r approx. 75 kDa was the only one that showed esterase activity. The crude medium, stored at –15 °C, maintained its initial hydrolytic activity on triacylglycerol for at least 42 days, though when it was kept for 10 days at 4 °C, the activity fell to 50%. Kinetic parameters using substrates such as triolein (TO), dipalmitoyl phosphatidylcholine (DPPC) and cholesteryl oleate (ChoO), were comparatively evaluated. The activity of the enzyme in the hydrolysis of TO showed the highest values, whereas the maximal specific activities were less when the enzyme was assayed against DPPC and ChoO.     

Effects of citronella oil (Cymbopogon winterianus Jowitt ex Bor) on Spodoptera frugiperda (J. E. Smith) midgut and fat body

The armyworm, Spodoptera frugiperda, is the principal pest of corn in Brazil. Control is achieved primarily by synthetic insecticides, which cause problems for the agro-ecosystem. Alternative methods of control are under investigation and citronella (Cymbopogon winterianus) essential oil appears to be a promising agent. We investigated the effects of citronella oil using histological, histochemical and immunohistochemical methods. The midgut of larvae treated with citronella exhibited altered epithelium including cytoplasmic protrusions, columnar cell extrusion, pyknotic nuclei, and increased periodic acid-Schiff positive granules. Regenerative cells in the epithelium of the midgut increased in number, which facilitated subsequent regeneration of this tissue. After exposure to citronella, trophocytes, the principal cell type of the fat body, possessed enlarged vacuoles and mitotic bodies, and contained reduced amounts of glycogen, lipid, and protein. Citronella oil caused morphological changes of the midgut and reduction of stored resources in the fat body, which may adversely affect insect reproduction and survival.     

EFFECT OF NITRATE CONCENTRATION ON THE RELATIONSHIP BETWEEN PHOTOSYNTHETIC OXYGEN EVOLUTION AND ELECTRON TRANSPORT RATE IN ULVA RIGIDA (CHLOROPHYTA)1

The electron transport rate (ETR) versus gross photosynthesis (GPS) relationship varies as a function of species, temperature, irradiance, and inorganic carbon levels, but less is known about the effect of nitrogen supply on this relationship. The objective of this study was to evaluate the effect of nitrate concentration on the ETR versus GPS relationship in Ulva rigida C. Agardh from the Mediterranean Sea. Chlorophyll content and tissue absorptance increased 2‐fold as nitrate in the media increased from 0 to 50 μM. Whereas internal N content increases 3‐fold at 50 μM, internal C increased slightly. Oxygen evolution and ETR, evaluated as in vivo chl fluorescence using pulse amplitude modulated fluorometry, in general saturated at irradiances above 100 μmol photons·m^?2·s^?1. Both maximum ETR and GPS values increased as nitrate concentration increased. In general, the ETR versus GPS relationship showed a linear response to increasing nitrate with little variance of the data. This relationship, however, became more variable at high irradiances and high nitrate concentrations. The ETR/GPS ratio was close to the theoretical value of 4 at low nitrate concentrations, and the ratio decreased exponentially when nitrate concentration in the media increased. The variations of ETR/GPS under different inorganic nitrogen supply are discussed in terms of the effect of nitrate on the photosynthesis and respiration relationship.     

Effects of environmental temperature on life tables of Rhodnius neivai Lent, 1953 (Hemiptera: Reduviidae) under experimental conditions.

Changes in life tables of Rhodnius neivai due to variations of environmental temperature were studied, based on nine cohorts. Three cohorts were kept at 22 degrees C, three at 27 degrees C and three at 32 degrees C. Cohorts were censused daily during nymphal instars and weekly in adults. Nine complete horizontal life tables were built. A high negative correlation between temperature and age at first laying was registered (r=-0,84). Age at maximum reproduction was significantly lower at 32 degrees C. Average number of eggs/female/week and total eggs/female on its life time were significantly lower at 22 degrees C. Total number of egg by cohort and total number of reproductive weeks were significantly higher at 27 degrees C. At 32 degrees C, generational time was significantly lower. At 27 degrees C net reproductive rate and total reproductive value were significantly higher. At 22 degrees C, intrinsic growth, finite growth and finite birth rates were significantly lower. At 22 degrees C, death instantaneous rate was significantly higher.