ClSnRK2.3 negatively regulates watermelon fruit ripening and sugar accumulation

Watermelon(Citrullus lanatus) as non-climacteric fruit is domesticated from the ancestors with inedible fruits. We previously revealed that the abscisic acid(ABA) signaling pathway gene ClSnRK2.3 might infuence watermelon fruit ripening. However,the molecular mechanisms are unclear. Here,we found that the selective variation of ClSnRK2.3 resulted in lower promoter activity and gene expression level in cultivated watermelons than ancestors, which indicated ClSnRK2.3 might be a negative regulator ...     

绿脓杆菌定值,定位,定性检测技术研究

为建立组织内细菌的定植、定位及定性检测方法,实验专用对绿脓杆菌定性、定量培养的DPA培养基,解决了同时定性、定量培养的难题,实验结果表明,同一标本有多个同种细菌生长可判定细菌定植。方法简单、可靠、重复性好。     

Transduction of modified factor VIII gene improves lentiviral gene therapy efficacy for hemophilia A

Hemophilia A (HA) is a bleeding disorder caused by deficiency of the coagulation factor VIII (F8). F8 replacement is standard of care, whereas gene therapy (F8 gene) for HA is an attractive investigational approach. However, the large size of the F8 gene and the immunogenicity of the product present challenges in development of the F8 gene therapy. To resolve these problems, we synthesized a shortened F8 gene (F8-BDD) and cloned it into a lentiviral vector (LV). The F8-BDD produced mainly short cleaved inactive products in LV-transduced cells. To improve F8 functionality, we designed two novel F8-BDD genes, one with an insertion of eight specific N-glycosylation sites (F8-N8) and another which restored all N-glycosylation sites (F8-299) in the B domain. Although the overall protein expression was reduced, high coagulation activity (>100-fold) was detected in the supernatants of LV-F8-N8- and LV-F8-299-transduced cells. Protein analysis of F8 and the procoagulation cofactor, von Willebrand Factor, showed enhanced interaction after restoration of B domain glycosylation using F8-299. HA mouse hematopoietic stem cell transplantation studies illustrated that the bleeding phenotype was corrected after LV-F8-N8 or -299 gene transfer into the hematopoietic stem cells. Importantly, the F8-299 modification markedly reduced immunogenicity of the F8 protein in these HA mice. In conclusion, the modified F8-299 gene could be efficiently packaged into LV and, although with reduced expression, produced highly stable and functional F8 protein that corrected the bleeding phenotype without inhibitory immunogenicity. We anticipate that these results will be beneficial in the development of gene therapies against HA.     

Duty ratio drive prediction model of lifetime degradation for organic light emitting diode-on-silicon microdisplay

A duty ratio drive prediction (DRDP) model of luminance degradation for organic light emitting diodes (OLED) microdisplay is proposed in this paper. The traditional stretched exponential decay (SED) model is not applicable for OLED driven by duty ratio. The DRDP model introduces the duty ratio as the variables affecting the lifetime of OLED. By fitting the undetermined coefficients with the measured luminance data, the quantitative relationships among the initial luminance, duty ratio, and OLED lifetime are obtained. Meanwhile, the model quantifies the phenomenon of spontaneous luminance recovery, which occurs when OLED switches from bright to dark. Finally, the DRDP model is used to compensate the luminance degradation of OLED driven by duty ratio. The experimental results show that the average prediction accuracy of DRDP model for white, red, green, and blue (W/R/G/B) OLED degradation trend is 0.9623. The average prediction accuracy of W/R/G/B OLED lifetime is 0.6119, which is greater than that of SED model. The lifetime is extended by 89.83% after compensation.     

Transmembrane potential responses during HL-60 promyelocyte differentiation

Myeloid cells, including granulocytes and monocyte/macrophages, are important in disease-associated inflammatory reactions. These cells come from a common progenitor, the promyelocyte. The human promyelocytic cell line, HL-60, can be induced to terminally differentiate into granulocytes or monocyte/macrophages in a controlled fashion providing a model to study various aspects of myelomonocytic differentiation. The expression of several ion channels is controlled in HL-60 cells in a differentiation specific pattern. The purpose of this study was to determine if lineage-specific ion channel expression during HL-60 differentiation resulted in differences in functional responses to external stimuli. This was investigated by examining transmembrane potential responses in HL-60 promyelocytes, HL-60-derived polymorphonuclear cells (PMNs), and monocytes to various stimuli using the transmembrane potential sensitive dye, diSBAC₂-(3). Exposure of HL-60 promyelocytes to ionomycin or ATP produced a membrane hyperpolarization. Studies using ion substitutions and ion channel blockers indicate that the hyperpolarization was mediated by K_Ca channels. During HL-60 promyelocyte differentiation to PMNs, the membrane potential response to ionomycin and ATP shifted from a hyperpolarization to a depolarization over 7 days. Conversely, HL-60-derived monocytes exhibited a membrane hyperpolarization in response to ionomycin and ATP. HL-60-derived monocytes also exhibit a Cl⁻ conductance specifically induced by ATP. Lineage-specific expression of ion channels during HL-60 cell differentiation is important in determining the transmembrane potential response of these cells. This may be translated into functional responses of various myelomonocytic cells during disease-associated inflammatory reactions. © 1996 Wiley-Liss, Inc.     

Recent advances in production of 5-aminolevulinic acid using biological strategies

5-Aminolevulinic acid (5-ALA) is the precursor for the biosynthesis of tetrapyrrole compounds and has broad applications in the medical and agricultural fields. Because of the disadvantages of chemical synthesis methods, microbial production of 5-ALA has drawn intensive attention and has been regarded as an alternative in the last years, especially with the rapid development of metabolic engineering and synthetic biology. In this mini-review, recent advances on the application and microbial production of 5-ALA using novel biological approaches (such as whole-cell enzymatic-transformation, metabolic pathway engineering and cell-free process) are described and discussed in detail. In addition, the challenges and prospects of synthetic biology are discussed.     

Biodiversity estimation of the western region of Ghana using arthropod mean morphospecies abundance

There is a global consensus on the fact that human activities are increasingly eroding biodiversity, especially in many ecologically rich regions of the world. Quantifying these biodiversity losses over large administrative areas, along with the impacts of the respective driving factors is necessary for biodiversity conservation. In this study, we used readily available spatial data on infrastructure, fragmentation, and land use together with ecological data on terrestrial arthropods (as species surrogate) to carry out spatial assessment and mapping of biodiversity values in the Western Region of Ghana, a highly degraded part of the West African biodiversity hotspot. Compared with its pristine condition, our results show that the region has a remaining mean species abundance (MSA) of approximately 52%, indicating a loss of 48% due to anthropogenic activities (mainly cocoa and oil palm farming). Areas of national protection (i.e. national parks and forest reserves) did not prove to have much promise for biodiversity conservation in the region since many were found to have low MSA values. Moreover, according to our arthropod data, no areas of high MSA values were found outside protected areas. However, because the thick, continuous, structurally complex canopies of these orchards responsible for the biodiversity loss provide natural connectivity between protected reserves, diversification of understory vegetation and a reduction in the use of agrochemicals particularly weedicides and pesticides may yield significant conservation outcomes.