Suppression of antibody response by excess dietary zinc exposure during certain stages of ontogeny

A study was made of the effects of excess dietary zinc on the antibody response to sheep red blood cells (SRBC) in mice. C57BL/6J mice were divided into 10 different dietary groups and exposed to diets containing zinc in normal (50 ppm) or excess (2000 ppm) concentrations during gestation/lactation/postweaning development in the sequences (1) 50/50/50; (2) 50/50/2000; (3) 2000/50/50; (4) 2000/2000/50; (5) 2000/50/2000; (6) 50/2000/50; (7) 50/2000/2000; (8) 2000/2000/2000; (9) 50/50/50 (pair-fed); and (10) chow/chow/chow. Mice in group 8 had severe signs of copper deficiency at 8 weeks of age, such as reduced plasma copper, lowered plasma hematocrit, and achromotrichia. Mice receiving 2000 ppm zinc during gestation had fewer offspring per litter (measured at 2 weeks of age) and more nonviable births than mice given 50 ppm zinc during gestation. The growth curve of mice exposed to excess zinc in the 50/50/2000 group was identical to that of the control (50/50/50) group. Growth curves for all other groups were reduced by varying amounts. The plaque-forming cell response to SRBC was reduced only in the groups receiving 50/2000/2000 and 2000/2000/2000 ppm zinc (P less than 0.05); this reduced response was not associated with atrophy of the lymphoid organs. Splenic cell surface markers and mitogenic responsiveness were similar in the 50/50/50 and 2000/2000/2000 groups. These results suggest that the immune response is more susceptible to dietary manipulation during development than after the immune response has been developed.     

Poor effectiveness of Natura 2000 beech forests in protecting forest-dwelling bats

With the establishment of the Natura 2000 (N2000) network, the European Union intends to develop strategies to conserve Europe's threatened habitats and species, including bats. Forest-dwelling bats are highly reliant on forest structures, such as snags and hollow trees, which the bats need as roosts. The decrease in such forest microhabitats significantly affects the habitat use and, therefore, the activity in forests. To determine whether N2000 beech forests under active timber production offer better habitats for bats compared to commercially used non-N2000 forests, we measured the bat activity and assessed the potential roosts in trees and snags in eleven pairs of stands. All survey stands represented mesotrophic beech forests (Fagus sylvatica L.) of the N2000 habitat type 9130 (Asperulo-Fagetum) in three European Biogeographic Regions. The activity of all bat species, the activity of priority N2000 species, the species number, the number of trees with roosts and the snag volume did not differ significantly between the N2000 and non-N2000 stands. We conclude that the current management of the N2000 beech forests is almost identical to that of non-N2000 commercial forests, and thus, the N2000 status has not led to an increase of bat-relevant habitat variables yet. Consequently, additional efforts beyond the administrative assignment of N2000 areas are required to build and ensure an ecologically effective and sustainable network of beech forests in Europe, including increasing important forest requirements for bats, such as roosts and snags.     

Lipid chain length effect on the phase behaviour of PCs/PEG:2000-PEs mixtures. A spin label electron spin resonance and spectrophotometric study

Spin-label electron spin resonance (ESR) spectroscopy and spectrophotometry at fixed wavelength are used to study fully hydrated aqueous dispersions of phosphatidylcholines (PCs) with poly(ethylene glycol:2000)-phosphatidylethanolamines (PEG:2000-PEs). PEG:2000-PE is a micelle-forming polymer-lipid that is extensively used for increasing the lifetime of PC liposomes in the blood circulation through a steric stabilisation effect. The PC lipids and the PEG:2000-PE polymer-lipids have the same acyl chain length of either dimiristoyl (DM) or distearoyl (DS) chains. DMPC/PEG:2000-DMPE and DSPC/PEG:2000-DSPE mixtures were investigated over the entire range of relative compositions (0-100 mol%). In both dispersions, the low-temperature conventional spin label ESR spectra and the temperature dependence of the absorbance at 400 nm give an indication of the conversion from lamellae to micelles with increasing PEG:2000-PEs content. The physical state of the lipid assemblies, lamellar or micellar, is dependent not only on PEG:2000-PEs content, but also on the length of hydrocarbon chain of the lipid matrix. Micellisation is attained more readily in dispersions with longer hydrocarbon chains (i.e. in DSPC/PEG:2000-DSPE mixtures) than in those with shorter acyl chains (i.e. in DMPC/PEG:2000-DMPE mixtures). Saturation transfer ESR (ST-ESR) and absorbance measurements reflect the disaggregation of the bilayers and a reduction in the size of the lipid aggregates by PEG:2000-PEs at low content.     

Effects of phosphatidylserine on membrane incorporation and surface protection properties of exchangeable poly(ethylene glycol)-conjugated lipids

Liposomes containing the acidic phospholipid phosphatidylserine (PS) have been shown to avidly interact with proteins involved in blood coagulation and complement activation. Membranes with PS were therefore used to assess the shielding properties of poly(ethylene glycol 2000)-derivatized phosphatidylethanolamine (PE-PEG(2000)) with various acyl chain lengths on membranes containing reactive lipids. The desorption of PE-PEG(2000) from PS containing liposomes was studied using an in vitro assay which involved the transfer of PE-PEG(2000) into multilamellar vesicles, and the reactivity of PS containing liposomes was monitored by quantifying interactions with blood coagulation proteins. The percent inhibition of clotting activity of PS liposomes was dependent on the PE-PEG(2000) content. 1,2-Distearoyl-sn-glycero-3-phosphoethanolamine (DSPE)-PEG(2000) which transferred out slowly from PS liposomes was able to abolish >80% of clotting activity of PS liposomes at 15 mol%. This level of DSPE-PEG(2000) was also able to extend the mean residence time of PS liposomes from 0.2 h to 14 h. However, PE-PEG(2000) with shorter acyl chains such as 1,2-dimyristyl-sn-glycero-3-phosphoethanolamine-PEG(2000) were rapidly transferred out from PS liposomes, which resulted in a 73% decrease in clotting activity inhibition and 45% of administered intravenously liposomes were removed from the blood within 15 min after injection. Thus, PS facilitates the desorption of PE-PEG(2000) from PS containing liposomes, thereby providing additional control of PEG release rates from membrane surfaces. These results suggest that membrane reactivity can be selectively regulated by surface grafted PEGs coupled to phosphatidylethanolamine of an appropriate acyl chain length.     

Natural antioxidants in the vitrification solution improve the ovine ovarian tissue preservation

The present study evaluated the effect of the addition of antioxidants anethole (AN) and robinin (RO) in the vitrification solution, and the in vitro incubation (IVI) medium of ovine ovarian tissue. Ovarian fragments were vitrified without antioxidant (VWA) or with different concentrations of AN (30, 300 and 2000 μg/mL) or RO (0.125, 0.25 and 0.50 mg/mL), followed by IVI (24 h). Histological analyses showed that the percentage of morphologically normal preantral follicles (MNPF) in AN 2000 did not differ from RO 0.125 or fresh ovarian tissue (CTR). Subsequently, ovarian fragments were vitrified in the presence of AN 2000 and RO 0.125 followed by IVI without or with (AN 2000+ and RO 0.125+) the same antioxidants. The follicular activation in all treatments was significantly increased as compared to the CTR. The stroma cell density (SCD) in all the vitrified fragments was significantly lower than the CTR. However, in the AN 2000 and RO 0.125 this parameter was significantly higher when compared to the VWA. The reactive oxygen species (ROS) in the ovarian cortex of the AN 2000 or AN 2000+ were significantly reduced in comparison with the CTR while the intracellular ROS levels of AN 2000 and CTR were similar. The total antioxidant capacity (TAC) in RO 0.125 was significantly higher than that of VWA, AN 2000 and AN 2000+. According to the results, the use of antioxidants (AN or RO) only in the vitrification solution of ovine ovarian tissue is recommended, due to their better preservation of the SCD. Moreover, AN 2000 best maintains the follicular morphology, while RO 0.125 has a high TAC.     

A novel strategy for inducing enhanced mucosal HIV-1 antibody responses in an anti-inflammatory environment

Prophylactic vaccination against HIV-1 sexual transmission will probably require antibody elicitation at genital mucosal surfaces. However, HIV-1 envelope glycoprotein (Env)-based antigens are weakly immunogenic, particularly when applied mucosally. The polyanion PRO 2000 is safe for human vaginal application, and thus may represent a potential formulating agent for vaginal delivery of experimental vaccine immunogens. Based upon its biochemical properties, we hypothesized that PRO 2000 might enhance mucosal immunogenicity of HIV-1 envelope glycoprotein (Env)-based antigens, promoting local and systemic immune responses. Vaginal immunization with Env-PRO 2000 resulted in significantly increased titres of Env-specific mucosal IgA and IgG in mice and rabbits, respectively, compared to Env alone, revealing modest but significant mucosal adjuvant activity for PRO 2000. In vitro, PRO 2000 associated with Env, protecting the glycoprotein from proteolytic degradation in human vaginal lavage. Unexpectedly, PRO 2000 antagonized TLR4 activation, suppressing local production of inflammatory cytokines. Since inflammation-mediated recruitment of viral target cells is a major risk factor in HIV-1 transmission, the immune modulatory and anti-inflammatory activities of PRO 2000 combined with its intravaginal safety profile suggests promise as an HIV-1 mucosal vaccine formulating agent.     

A survey on non specialized off-the-shelf JPEG2000 viewers for digital microscopy use

The present paper will present a survey on features of a number of non-specialized off-the-shelf JPEG2000 viewers, seen from the point of view of digital microscopy. Selected viewers were tested within a number of usage scenarios, including: i) open a conformance test JPEG2000 file; ii) open a large JPEG2000 file; iii) moving from one point to another; iv) changing resolution/magnification. For each scenario, data recorded included: successful or unsuccessful operation; time needed for conclusion; occasional problems.Preliminary results demonstrate that JPEG2000 conformance as stated by many viewers is only limited to some of the possibilities of the JPEG2000 standard, in particular for what regards file size.     

阳离子脂质体介导基因转染肿瘤细胞

使用基因转运载体运载肿瘤细胞进行转染是基因治疗的关键环节之一。Lipo-fectamine2000和DOTAP作为商品转染试剂,具有较高的转染效率。为了进一步发掘其作为基因转运载体的应用潜力,该文研究了Lipofectamine2000和DOTAP的粒径、Zeta电位及形态,并分别与绿色荧光蛋白基因（pGFP—N2）、荧光素酶基因（pGL3）结合,形成脂质体／DNA复合物,通过载入人喉癌细胞（Hep-2）和人肺癌细胞（NCI—H460）,考察了其转染效率和细胞毒性。结果表明,脂质体Lipofectamine2000与DOTAP都能有效压缩DNA,形成复合物。Lipofectamine2000与DOTAP井目比,转染效率高,与DNA最佳转染比例范围为2：1～4：1。毒性实验显示,在N／P大于3／l时,Lipofectamine2000与DOTAP对癌细胞具有一定的细胞毒性。细胞种类对脂质体的转染效率有很大影响,Lipo—fectamine2000对Hep－2细胞的转染效率比NcI—H460高。     

Literature on archaeological remains of cultivated plants (1999/2000)

Publications on archaeological remains of cultivated plants have been collected, mainly from 1999, with some earlier and some from 2000. A list is given of the finds according to taxon, country, site, and age. Received November 22, 2000 / Accepted November 27, 2000     

Patterns of Allelic Diversity in Spring Wheat Populations by SSR-Markers

Precise assessment of diversity in available breeding germplasm helps to preempt epidemics and abrupt environmental changes. Spring wheat germplasm consisting of 84 accessions including cultivars, breeding lines and landraces from various origins was scanned with 44 SSRs. For allele frequencies, allelic patterns, heterozygosity and polymorphism the selected population was divided in three subpopulations: (i) pre-green revolution (pre-1965), (ii) post-green revolution (post-1965), (iii) post-veery (post-2000). Alleles produced in pre-1965, post-1965 and post-2000 subpopulations were 115, 144 and 131, respectively. Mean PIC values for pre-1965, post-1965 and post-2000 subpopulations were 0.48, 0.52 and 051, respectively. Allelic patterns showed no locally common alleles in any of the subpopulation. The pre-1965 subpopulation had also no private allele, however, average number of private alleles decreased from post-1965 to post-2000 subpopulation. In case of effective alleles and Shannon’s information index trend was increasing from pre-1965 to post-1965 and then decreasing from post-1965 to post-2000. The decreasing trend alarms the reduced genetic diversity in wheat varieties developed after 2000. PCA and cluster analysis didn’t clearly differentiated subpopulations, though pre-1965 genotypes showed higher genetic distance from post-1965 and post-2000 subpopulations. The decreasing measures of genetic diversity in post-2000 wheat genotypes should be a concern for wheat breeders, therefore, all sources of broadening genetic diversity should be exploited.     

Osmotic pressure and aggregate shape in BSA/poly(ethylene glycol)-lipid/Dextran solutions

In this work we study the colloidal osmotic pressure (COP) and aggregate shape in phosphate saline buffer solutions (pH 7.4) containing bovine serum albumin (BSA), poly(ethylene glycol) lipid (PEG(2000)-PE) and Dextran (Dx). Dx was added to the BSA/PEG(2000)-PE system in order to increase the COP of the solution to levels comparable to the COP of healthy adults, with the aim of using the solution as a blood COP regulator. Dynamic light scattering and small angle X-ray scattering results shown the formation of BSA/PEG(2000)-PE/Dx aggregates in the solution. Osmometry results shown that the addition of Dx to the BSA/PEG(2000)-PE system could successfully increase the COP, through the formation of BSA/PEG(2000)-PE/Dx aggregates. The BSA/PEG(2000)-PE/Dx solutions attained COP=15 mm Hg, representing 60% of COP measured for healthy adults.     

The Introduction of Nonnative Fish into Wilderness Lakes: Good Intentions, Conflicting Mandates, and Unintended Consequences

Received 28 March 2000; accepted 12 April 2000.     

Cloning, structure, expression analysis, and assignment to mouse Chromosome 7 of the gene Zfp296 encoding a zinc finger protein

Received: 4 May 2000 / Accepted: 16 June 2000     

Biased Sex Allocation in Hermaphroditic Plants

Received 8 June 2000/ Accepted in revised form 7 July 2000     

Flavonoids of Leguminous Plants: Structure, Biological Activity, and Biosynthesis

Received 25 August 2000/ Accepted in revised form 2 October 2000     

Effects of drought during grain filling on PS II activity in rice

The Rice varieties Araure 4 (A4) and Fonaiap 2000 (F2000) were grown in the glasshouse under natural sunlight and subjected to drought at heading. The drought induced changes in chlorophyll a fluorescence parameters, pigment composition, D1 contents and carbohydrate accumulation were investigated. Drought decreased phiPS II, FV'/FM' and qP, and increased qN in both varieties. F2000 had larger values of phiPS II and FV'/FM' at a lower RWC than A4. With the onset of drought only A4 increased the xanthophyll cycle pool, F2000 remaining constant throughout the drought cycle. Irrigated plants of A4 had a Larger de-epoxidation state (DEPS) of the xanthophyll cycle than F2000. A 40% increase in DEPS was induced by drought in both varieties but in A4 it was attained at a larger RWC than in F2000. Drought increased glucose and fructose contents of leaves 8-fold in A4 and 3-fold in F2000. Contrarily, sucrose contents decreased with drought but the effects were larger in A4 than in F2000. Sugars accumulation preceded and was proportional to the decrease in PS II activity elicited by drought in both varieties. In F2000 a decrease in D1 content smaller than 20% occurred at 70% of RWC, whereas droughted plants of A4 had lost 80% of D1 protein at 77% of RWC. Our data show that drought severely affected PS II activity and its main regulatory mechanisms in rice. There are genotypic differences in the response of PS II activity to drought that could be exploited as traits for selection to drought tolerance. There is a possible link between the drought-induced sugars accumulation in the flag leaf and the response of PS II to water deficit.     

Changes in Cell Wall Polysaccharides During Fruit Ripening

Received 20 June 2000/ Accepted in revised form 20 July 2000     

Effects of High Temperature on the Development of Pollen Mother Cells and Microspores in Barley Hordeum vulgare L.

Received 15 May 2000/ Accepted in revised form 26 August 2000     

Immunological specificity and biological action of biliary glucagon-like substance in the rabbit

A glucagon-like substance named biliary IRG2000 whose molecular weight is approximately 2,000 was isolated by gel filtration from rabbit bile. This substance showed a strong crossreactivity as equivalent to 25.7 +/- 5.1 ng/ml of porcine glucagon in RIA with antiserum 30K specificity. Biliary IRG2000 brought about a significant increase and delayed the response of blood glucose level in coexistence with porcine glucagon, though it has no appreciable effect on the glucose level when administered singly to the mouse intraperitoneally. The response with the coexistence of these materials was far greater than when porcine glucagon was given alone. In Mortimore's type rat liver perfusion, a significant rise in glucose concentration in effluent was also observed when a mixture of biliary IRG2000 and porcine glucagon was perfused. The rate of 125I-glucagon degradation was found delayed in the presence of biliary IRG2000 when examined in the rat. Thus the increase and delayed response of glucose level in coexistence of porcine glucagon with biliary IRG2000 may be explained by a suppressive effect of glucagon degradation due to biliary IRG2000.