Conversion of sugar-beet particles to ethanol by the bacteriumZymomonas mobilis in solid-state fermentation

Summary The possibility of usingZymomonas mobilis as the microorganism, in solid-state fermentation of sugar-beet particles was investigated. The major factors affecting the process were investigated and related to ethanol yield and productivity. Ethanol yield of 0.48 g/g sugar, volumetric productivity of 12 g/L h, and final ethanol concentration of 130 g/L show the good performance ofZ.mobilis in a solid-state fermentation.     

Suppression of anti-hapten antibody responses by hapten-specific cytolytic T lymphocytes: role of I-A-associated antigen on target B lymphocytes

Cytolytic T lymphocytes (CTL) specific for 2,4,6-trinitrophenyl (TNP) determinants suppress the effector phase of a secondary anti-TNP antibody responses of murine syngeneic spleen cells in vitro. The cells mediating this suppression are hapten-specific, H-2-restricted, and possess properties typical of CTL. Moreover, the targets of the suppression appear to be antigen-primed B lymphocytes that are recognized by CTL via soluble antigen bound noncovalently to their Ig receptors. The effect of the CTL can be blocked by the addition of monoclonal antibodies directed against I-A molecules but not I-E or H-EK-encoded molecules on the target B cells, even in strain combinations in which the CTL-B cell interaction is restricted only by the H-2K and I regions of the MHC. This result suggests that B lymphocyte-bound antigen tends to associate preferentially with I-A rather than H-2K/D-encoded determinants, and that the suppressive effect of the CTL population is attributable to the minor subset that recognizes hapten-modified Ia antigens. These findings are also discussed in terms of the possible immunoregulatory function of Ia-restricted CTL.     

In vitro activation and behavior of the ameboid sperm of Ascaris suum (Nematoda)

Summary A system is described for the study of activation and motility of Ascaris spermatozoa in vitro. Activation was accomplished by addition of the sperm-activating substances (SAS), extracted from the male accessory gland, to cells incubated in phosphate-buffered saline (pH 7.4) at 37–39° C under anaerobic conditions (95% N₂, 5% CO₂). Activation is characterized by a change from spherical to ameboid shape with coalescence of the refringent granules. The normal ameboid spermatozoa bear several stubby and needle-like filopodia at the lamellipodial margin. Within the lamellipodium are bundles of microfilament-like structures extending toward the pseudopodial membrane and concentrating within the needle-like filopodia. These filopodia exhibit a pendulous, sweeping motion with subsequent retraction and disappearence within the main lamellipodium. Membranes of the ameboid cells interact at the pseudopodial regions with partial fusion, as suggested by apparent membrane breakdown between interdigitating portions of the pseudopodia. Activation is complete in 5–15 min, is totally inhibited at 4° C and/or by an atmospheric environment, but can be reinitiated by transfer to anaerobic conditions at 22–9° C. Activation also requires favorable pH (6.8–8.7) and continual exposure to sufficiently high sodium concentrations (134–154mM), i.e., lowering of sodium concentration to 10 mM causes irreversible inactivation. Sodium may be replaced by potassium or lithium but not by Tris or sucrose. Proteinases (10 g/ml) can act as activators even though SAS lack detectable proteolytic activity against azoalbumin, azocasein, TAME and BTEE and SAS activation was not inhibited by TLCK or soybean trypsin inhibitor.Adult Ascaris suum were provided through the generosity of Wilson and Company, Cedar Rapids, Iowa, U.SA. This study was supported by grant number 5T01 HD00152 and postdoctoral fellowship 1F 32AI05646 from the National Institute of Health, U.S.A.     

The distribution of Ia antigens on the surfaces of lymphocytes.

The distribution of Ia antigens was studied on murine spleen lymphocytes by an ultrastructural technique employing deep freeze-etched replicas. Ia antigens were labeled on cells from appropriate congenic and recombinant strains of mice by incubating the cells with FITC-conjugated anti-Iak antibody, followed by ferritin-coupled Fab anti-FITC. Ia antigens were detected predominantly on immunoglobulin (Ig)-bearing B lymphocytes. Antigens coded for by the entire Ik region were present on the surfaces of 95% of the positive cells (from B10.BR mice) in densely packed microclusters. Ia specificities coded for by the I-A and I-C subregions (on 4R and B10.HTT mice) exhibited a more variable pattern, with 30 to 35% of the labeled cells having sparsely distributed Ia antigens in relatively discrete microclusters. Binding of anti-Iak antibody at 37 degrees C led to patch formation but not to capping. Modulation of surface Ig left Ia antigens diffusely distributed on the cell surface, indicating that these two membrane proteins are independent molecules.     

基于MaxEnt模型的甘肃安西极旱荒漠国家级自然保护区北山羊生境评估

明晰甘肃安西极旱荒漠国家级自然保护区珍稀濒危物种北山羊的分布格局,并阐释气候变化和人类活动对北山羊的影响,对今后北山羊生境管理和物种保护具有重要意义。基于北山羊实测分布点记录和环境变量数据,结合MaxEnt模型和ArcGIS空间分析功能,利用CMIP6的8个气候模式均值预测中度发展路径（SSP2-4.5）下,基准期（1970-2000年）和未来气候（2041-2060年、2081-2100年）变化情景下,甘肃安西极旱荒漠国家级自然保护区北山羊的潜在适生区分布范围及变化,并综合贡献率和置换重要性值对北山羊生境选择关键环境因子进行了分析。研究结果表明：（1） MaxEnt模型的预测精度较高,三种气候条件下ROC曲线下面积（AUC,Area Under Curve）>0.97,且真实技巧统计（TSS,True Skill Statistic）>0.90,模拟结果可靠。（2）影响北山羊生境选择的主要环境因子为气候条件（降水量季节性变异系数和等温性）、海拔和人为干扰（距泉和居名点距离）。水是保护区北山羊生存的最基本要素,气候条件共同控制北山羊生境条件。此外,北山羊习性决定其生境宜选择高海拔和远离人类活动影响地区。（3）基准期保护区北山羊主要分布在北片和南片高海拔山区,面积365.77 km²（占整个保护区的4.31%）,北山羊适生区面积北片>南片、中高等适生区主要位于保护区北片。（4） CMIP6未来气候变化情景下,随着保护区生态环境改善和濒危物种保护措施的实施,北山羊潜在适生区面积呈增加趋势,但是受北山羊近亲繁殖的影响,整体上北山羊数量和适生区面积增加并不显著且有向南部及高海拔地区转移趋势。     

Virtual assessment,training, and evaluation of clinical laboratory technologists amidst peak Covid-19 pandemic: An observational study

Medical technologists are considered a neglected group when it comes to academic interventions. We developed and implemented an educational intervention and assessment for the technologists based on an online questionnaire as a pre-test consisting of questions related to knowledge (n=5), attitude (n=3), and practices (n=4) of daily internal quality control (QC) monitoring via Google Docs survey tool. This study served multiple purposes. It allowed keeping the technologists engaged during the peak of the COVID-19 pandemic while also improving the knowledge, attitude, and practices about the internal quality control using Bio-Rad Unity Real Time (URT) QC software. Subjects were graded based on the scores they received out of 100 (0-60 = poor; 61-79 = good; 80-100 = excellent). Training materials, i.e., a set of 5 videos every week via e-mail, were circulated. A voice-over PowerPoint presentation was also shared for easy comprehension. This activity was repeated after one month. A post-test was administered to assess the improvement. The study results show significant improvement in the technologists'' performance after the intervention.     

Kinetic Changes of Ptdins (3,4,5) P3 within Fast and Slow Turnover Rates of Focal Adhesion

Background:The assembly and disassembly of the focal adhesions (FA) components occurs throughout life cycle of adhesion, with conservation of balance between removal and recruitment rate during temporal stages. Previous studies have demonstrated that phosphotidyilinositols play a role in regulating FA turnover. However, a little attention has been given to quantify the dynamics changes of Phosphatidylinositol 3,4,5-trisphosphate (PtdIns (3,4,5) P3) within and during fast and slow turnover rates of FA.Methods:In this study, we developed a protein purification MDA-MB-231 breast cancer cell line was used as a model in this study due to high metastatic and motile. These cells were co-transfected with GFP- paxillin/vinculin, as FA marker, and the GFP/mCherry-Btk-PH, as a biosensor to visualize PtdIns (3,4,5) P3. Confocal time-lapse images were used to monitor changes or differences in the local generation of PtdIns (3,4,5) P3 within and during assembly and disassembly of FA. Following transfection, immunostaining was used to examine the spatial co-localization between FA and PtdIns (3,4,5) P3.Results:Our data demonstrated that PtdIns (3,4,5) P3 co-localized with FAs and increase during assembly and decline during disassembly of FA which exhibits slow turnover rates and was in a constant level during assembly and disassembly of FA that displays fast turnover rates.DiscussionOur result suggested that the dynamic changes of PtdIns (3,4,5) P3, it may depend on components undergo turnover, such that early, nascent FA displays fast turnover rates and mature FA exhibits slow turnover rates. Thus, the local enrichment of PtdIns (3,4,5) P3 enhances FA assembly and disassembly activation.Key Words: Cancer cell migration, Focal adhesion turnover, MDA-MB-231 cell line, PtdIns (3,4,5) P3     

An exact analysis for a solute transport,due to simultaneous dialysis and ultrafiltration,in a hollow-fibre artificial kidney

Transport of a uremic solute effected by a combined dialysis and ultrafiltration procedure in a hollow-fibre artificial kidney, is investigated theoretically under standard assumptions. An exact analytical solution for the concentration profile in a blood channel is obtained by using the method of separation of variables. The necessary requirement that the solution must tend to that of pure dialysis, in the limit ultrafiltration tending to zero, is fulfilled. Exact analytical expressions are derived for the eigenconstants of the solution. In using the solution, the solute clearance is emphasized. Diffusive and ultrafiltration components of the solute clearance are defined and studied. The combined procedure is examined for middle versus small molecules and for polyacrylonitrile versus cuprophan hollow-fibres.