Antitumour activities of levans produced by Zymomonas mobilis strains

Levans produced by four Zymomonas mobilis strains showed antitumour activity against sarcoma 180 and Ehrlich carcinoma in Swiss albino mice. Levans from two strains (ZAP and CP4) had the highest effects. NMR analysis showed that the polymers were composed only of fructose units. The results suggested that the antineoplasic effect is associated to the polysaccharide molecular weight and that a particular molecular weight range may be responsible for this effect.     

A population genetic study of the Banks and Torres Islands (Vanuatu) and of the Santa Cruz Islands and polynesian outliers (Solomon Islands)

As part of a multidisciplinary survey of populations in the Banks and Torres Islands of Vanuatu and the Southern and Central Districts of the Solomon Islands, nearly 2,400 persons have been tested for ABO blood groups and a number of serum protein and red cell enzyme genetic marker systems. For the ABO system, the populations are characterized in general by high gene O and low gene B frequencies except in two of the Polynesian Outlier Islands, Rennell and Bellona, which have high frequencies of B. Among the serum proteins, several alleles have distributions indicating significant movement of people between islands. These include Albumin ^{New Guinea} and the transferrin alleles Tf, and Tf, and Tf. Similar specific alleles for red cell enzymes also show distributions reflecting interisland population movement as well as contact with persons from outside the southern Pacific region. Examples are ACP in the acid phosphatase system, PGM and PGM, PGM and PGM, PGK⁴ and also HbJ^Tongariki. The data available for 11 polymorphic systems were used to generate genetic distances. Of the four Polynesian Outlier Islands, Anuta is most remote genetically, with Rennell and Bellona also relatively isolated. The fourth Polynesian Outlier, Tikopia, occupies a position genetically close to the Melanesian populations of the Banks and Torres Islands and the southern Solomons. The history of early European contact and voyaging in the Pacific, as well as archaeological and linguistic evidence and local legends, indicate that significant movements of people occurred between islands and provided opportunities for genes to be introduced from Europeans, Africans, and Asians. The genetic marker studies give evidence for genes from all these sources, though at a low level. Despite this admixture, the Polynesian Outlier and Melanesian populations have preserved their own distinctive genetic patterns.     

Lack of prominent compensatory polycythemia in traditional native Andeans living at 4,200 meters

Red blood cell count (RBC), hemoglobin concentration ([Hb]) and hematocrit (Hct) were measured in 303 male Quechua children and adults, aged 6 to 57 years, living a lifestyle as traditional pastoralists and horticulturalists at a mean altitude of 4,200 m in the Southern Peruvian Andes. Values for RBC, [Hb], and Hct increased with age from middle childhood to young adulthood. However, among adults there was no significant association between age and any of these three parameters. Overall, there was approximately a 10-12% increase in the RBC, [Hb], and Hct above sea-level norms for all age groups. Mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH) showed a slight but significant increase with age in children and adolescents, but the mean corpuscular hemoglobin concentration (MCHC) did not. We conclude that the study of highland Quechua Indians, living a traditional lifestyle as pastoralists and horticulturalists, does not support the long-held belief that altitude hypoxia provokes a dramatic compensatory polycythemia in healthy Andeans.     

QMEANclust: estimation of protein model quality by combining a composite scoring function with structural density information

Background  

The selection of the most accurate protein model from a set of alternatives is a crucial step in protein structure prediction both in template-based and ab initio approaches. Scoring functions have been developed which can either return a quality estimate for a single model or derive a score from the information contained in the ensemble of models for a given sequence. Local structural features occurring more frequently in the ensemble have a greater probability of being correct. Within the context of the CASP experiment, these so called consensus methods have been shown to perform considerably better in selecting good candidate models, but tend to fail if the best models are far from the dominant structural cluster. In this paper we show that model selection can be improved if both approaches are combined by pre-filtering the models used during the calculation of the structural consensus.     

Variation in heat shock proteins within tropical and desert species of poeciliid fishes

The 70-kilodalton heat shock protein (hsp70) family of molecular chaperones, which contains both stress-inducible and normally abundant constitutive members, is highly conserved across distantly related taxa. Analysis of this protein family in individuals from an outbred population of tropical topminnows, Poeciliopsis gracilis, showed that while constitutive hsp70 family members showed no variation in protein isoforms, inducibly synthesized hsp70 was polymorphic. Several species of Poeciliopsis adapted to desert environments exhibited lower levels of inducible hsp70 polymorphism than the tropical species, but constitutive forms were identical to those in P. gracilis, as they were in the confamilial species Gambusia affinis. These differences suggest that inducible and constitutive members of this family are under different evolutionary constraints and may indicate differences in their function within the cell. Also, northern desert species of Poeciliopsis synthesize a subset of the inducible hsp70 isoforms seen in tropical species. This distribution supports the theory that ancestral tropical fish migrated northward and colonized desert streams; the subsequent decrease in variation of inducible hsp70 may have been due to genetic drift or a consequence of adaptation to the desert environment. Higher levels of variability were found when the 30- kilodalton heat shock protein (hsp30) family was analyzed within different strains of two desert species of Poeciliopsis and also in wild-caught individuals of Gambusia affinis. In both cases the distribution of hsp30 isoform diversity was similar to that seen previously with allozyme polymorphisms.      

三种兰科植物的保护遗传学研究初探

采用随机扩增多态 DNA(RAPD)分析研究了中国3种珍稀濒危兰科植物硬叶兜兰(Paphiopedilum micranthum Tang et Wang)、麻栗坡兜兰(P. malipoense S.C.Chen et Tsi)和独花兰(Changnienia amoena Chien)的遗传多样性与群体遗传结构.12个RAPD引物在2种兜兰中共扩增出131条带.对4个硬叶兜兰群体的检测表明其物种水平的多态条带百分率(PPB)为 71.6%,Nei 的基因多样度(h)为 0.217 1,Shannon多样性指数 (I) 为 0.330 1;4个群体的平均多样性水平为 PPB = 45.2%,h = 0.145 7,I = 0.220 4,低于远交兰花的平均水平.在总遗传变异中,群体间遗传变异占20.31%,略高于远交物种的平均水平.在物种水平上,麻栗坡兜兰的PPB为49.5%,h为0.117 4,I为0.176 4,均大大低于硬叶兜兰.对11个独花兰群体采用16个RAPD引物共扩增出119条带.物种水平PPB=76.5%,h=0.194 1,I=0.305 8;在群体水平上,上述3个指标的平均值则分别为37.2%、0.119 7和0.181 0,均低于远交兰花的平均水平.群体间的遗传变异占45.27%,遗传分化明显高于远交物种的平均水平.导致3个物种遗传多样性偏低而群体间遗传分化较高的主要原因在于人为的过度采挖和生境的片断化.研究结果为兰花保护策略和措施的制定提供了理论基础.     

Effects of long-term fixation on histological quality of undecalcified murine bones embedded in methylmethacrylate

While long-term fixation and storage of specimens is common and useful for many research projects, it is particularly important for space flight investigations where samples may not be returned to Earth for several months (International Space Station) or years (manned mission to Mars). We examined two critical challenges of space flight experimentation: the effect of long-term fixation on the quality of mouse bone preservation and the preservation of antigens and enzymes for both histochemical and immunohistochemical analyses, and how the animal/sample processing affects the preservation. We show that long-term fixation minimally affects standard histological staining, but that enzyme histochemistry and immunolabeling are greatly compromised. Further, we demonstrate that whole animal preservation is not as suitable as whole leg or stripped leg preservation for long-term fixation and all histological analyses. Overall, we recommend whole leg processing for long-term storage of bone specimens in fixative prior to embedding in plastic for histological examination.     

Factors influencing in the response of <i>Schizolobium parahybum</i> (Vell) Blake to <i>Ceratocystis paradoxa</i> and <i>C. moniliformis</i>

In the Ecuadorian coast one of the most destructive diseases of the pachaco is vascular wilt or stem rot caused by Ceratocystis complex, so the aim of this study was to determine the factors that affect the efficiency of the reaction of bark pachaco to this disease. This research was conducted under laboratory conditions, using trees pachaco S38, S41, S98, AE-1, AE-2 and AE-3, and pathogenic species Ceratocystis paradoxa and C. moniliformis. The method utilized was tissue stem bark,with bark sections with 4.5 cm², and a suspension of 3x10⁴ units infection and remained in a humid chamber for 96 hours at 25 ± 5 °C. Were determined grades of resistance/ susceptibility using a scale from 0 to 4, depending on the amount of mycelia and peritecio in each plant sample. Three factors were used: four colonies obtained by several transfers from each fungal specie, four ages of colonies of each fungal specie and four volumes of inoculum applied (units of infection), using for each experiment separately Completely Randomized Design with 4 replications factorial arrangement. For comparison between treatment means was used Tukey test at 5% probability of error. For future trials using this technique, you could use 30-day colonies for C. paradoxa and 40 days for C. moniliformis, and an application volume of 100 μL/cm², it would improve the level of response for the formation of perithecium and mycelia in samples cortex.     

Weight variation by sex and nature of risk factors in high-risk infants: an evolutionary perspective

A retrospective cohort study was conducted to explore growth variation during the intrauterine and early postnatal period by sex and nature of high-risk factors (i.e. physiological and pathological) in 831 Korean infants at a University hospital. The results showed that infants with a physiological risk showed a more congruent intrauterine growth pattern compared to those with a pathological risk. Particularly with a physiological risk, female infants experienced more compatible intrauterine and postnatal growth than males, although male infants were heavier than female infants at a given gestational age. In conclusion bigger may not necessarily be better for prenatal growth in humans. A more confluent intrauterine growth in infants with physiological risk can be beneficial for early postnatal catch-up growth. From an evolutionary perspective, female infants with a physiological risk may keep their advantageous edge over male infants during the early postnatal period although such an advantage may not be present with a pathological condition.