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151.
Priya Padmanabhan Mukund R. Shukla J. Alan Sullivan Praveen K. Saxena 《Plant Cell, Tissue and Organ Culture》2017,128(1):145-160
C4 plants can efficiently accumulate CO2 in leaves and thus reduce wasteful oxygen fixation by the RuBisCO enzyme. Three C4 enzymes, namely carbonic anhydrase (CA), phosphoenol pyruvate (PEPC) and pyruvate orthophosphate dikinase (PPDK), were over expressed in Oryza sativa L. ssp. indica var. Khitish under the control of green tissue specific promoters PD54o, PEPC and PPDK, respectively. Integration of these genes was confirmed by Southern hybridization. The relative expression of PEPC, CA and PPDK were, respectively, 6.75, 6.57 and 3.6-fold higher in transgenic plants compared to wild type plants (control). Photosynthetic efficiency of the transgenic plants increased significantly along with a 12?% increase in grain yield compared to wild type plants. Compared to control plants, transgenic plants also showed phenotypic changes such as increased leaf blade size, root biomass, and plant height and anatomical changes such as greater leaf vein number, bundle sheath cells, and bulliform cells. Our findings indicate that the combined over expression of these three enzymes is an efficient strategy for incorporating beneficial physiological and anatomical features that will enable subsequent yield enhancement in C3 rice plants. 相似文献
152.
Shibin Gao Carlos Martinez Debra J. Skinner Alan F. Krivanek Jonathan H. Crouch Yunbi Xu 《Molecular breeding : new strategies in plant improvement》2008,22(3):477-494
Leaf collection from the field, labeling and tracking back to the source plants after genotyping are rate limiting steps in
leaf DNA-based genotyping. In this study, an optimized genotyping method using endosperm DNA sampled from single maize seeds
was developed, which can be used to replace leaf DNA-based genotyping for both genetic studies and breeding applications.
A similar approach is likely to be suitable for all plants with relatively large seeds. Part of the endosperm was excised
from imbibed maize seeds and DNA extracted in 96-tube plates using individuals from eight F2 populations and seven inbreds. The quality of the resultant DNA was functionally comparable to DNA extracted from leaf tissue.
Extraction from 30 mg of endosperm yields 3–10 μg DNA, which is sufficient for analysis of 200–400 agarose-gel PCR-based markers,
with the potential for several million chip-based SNP marker analyses. By comparing endosperm DNA and leaf DNA for individuals
from an F2 population, genotyping errors caused by pericarp contamination and hetero-fertilization were found to average 3.8 and 0.6%,
respectively. Endosperm sampling did not affect germination rates under controlled conditions, although under normal field
conditions the germination rate, seedling establishment, and growth vigor were significantly lower than that of non-sampled
controls for some genotypes. However, careful field management can compensate for these effects. Seed DNA-based genotyping
lowered costs by 24.6% compared to leaf DNA-based genotyping due to reduced field plantings and labor costs. A substantial
advantage of this approach is that it can be used to select desirable genotypes before planting. As such it provides an opportunity
for dramatic improvements in the efficiency and selective gain of breeding systems based on optimum combinations of marker-assisted
selection and phenotypic selection within and between generations. 相似文献
153.
Brotherton P Endicott P Sanchez JJ Beaumont M Barnett R Austin J Cooper A 《Nucleic acids research》2007,35(17):5717-5728
Ancient DNA (aDNA) research has long depended on the power of PCR to amplify trace amounts of surviving genetic material from preserved specimens. While PCR permits specific loci to be targeted and amplified, in many ways it can be intrinsically unsuited to damaged and degraded aDNA templates. PCR amplification of aDNA can produce highly-skewed distributions with significant contributions from miscoding lesion damage and non-authentic sequence artefacts. As traditional PCR-based approaches have been unable to fully resolve the molecular nature of aDNA damage over many years, we have developed a novel single primer extension (SPEX)-based approach to generate more accurate sequence information. SPEX targets selected template strands at defined loci and can generate a quantifiable redundancy of coverage; providing new insights into the molecular nature of aDNA damage and fragmentation. SPEX sequence data reveals inherent limitations in both traditional and metagenomic PCR-based approaches to aDNA, which can make current damage analyses and correct genotyping of ancient specimens problematic. In contrast to previous aDNA studies, SPEX provides strong quantitative evidence that C > U-type base modifications are the sole cause of authentic endogenous damage-derived miscoding lesions. This new approach could allow ancient specimens to be genotyped with unprecedented accuracy. 相似文献
154.
155.
A subset of genes, known as imprinted genes, is present in the mammalian genome. Genomic imprinting governs the monoallelic expression of these genes, depending on whether the gene was inherited from the sperm or the egg. This parent-of-origin specific gene expression is generally dependent on the epigenetic modification, DNA methylation, and the DNA methylation status of CpG dinucleotides residing in loci known as differentially methylated regions (DMRs). The enzymatic machinery responsible for the addition of methyl (-CH(3)) groups to the cytosine residue in the CpG dinucleotides are known as DNA methyltransferases (DNMTs). Correct establishment and maintenance of methylation patterns at imprinted genes has been associated with placental function and regulation of embryonic/fetal development. Much work has been carried out on imprinted genes in mouse and human; however, little is known about the methylation dynamics in the bovine oocyte. The primary objective of the present study was to characterize the establishment of methylation at maternally imprinted genes in bovine growing oocytes and to determine if the expression of the bovine DNMTs-DNMT3A, DNMT3B, and DNMT3L-was coordinated with DNA methylation during oocyte development. To this end, a panel of maternally imprinted genes was selected (SNRPN, MEST, IGF2R, PEG10, and PLAGL1) and putative DMRs for MEST, IGF2R, PEG10, and PLAGL1 were identified within the 5' regions for each gene; the SNRPN DMR has been reported previously. Conventional bisulfite sequencing revealed that methylation marks were acquired at all five DMRs investigated in an oocyte size-dependent fashion. This was confirmed for a selection of genes using pyrosequencing analysis. Furthermore, mRNA expression and protein analysis revealed that DNMT3A, DNMT3B, and DNMT3L are also present in the bovine oocyte during its growth phase. This study demonstrates for the first time that an increase in bovine imprinted gene DMR methylation occurs during oocyte growth, as is observed in mouse. 相似文献
156.
Greater than one-half of the world's population harbors Helicobacter pylori. The majority of infected individuals, however, remain asymptomatic, with only 10% to 20% developing diseases, including peptic ulcer disease, gastric cancer, and gastric mucosa–associated lymphoid tissue lymphoma. This article reviews host factors that may predispose an individual to both the acquisition of H. pylori infection and subsequent clinical outcome. Individuals with specific blood group antigens and human leukocyte antigen genotypes may be more susceptible to H. pylori infection. Additional factors, such as the age of acquisition, the host immune response, the site of infection, acid secretion, and interactions with nonhost factors (including bacterial virulence factors and environmental influences) may play a role in determining clinical outcome. Further investigation is required to clarify the mechanisms by which these interactions occur and, more critically, to determine their relative importance. This knowledge will enable the identification of individuals at risk of developing clinical disease with H. pylori infection. 相似文献
157.
Top‐down control of species distributions: feral cats driving the regional extinction of a threatened rodent in northern Australia 下载免费PDF全文
158.
159.
Abstract Legionella pneumophila occurring in drinking water was subjected to environmental stress through holding tests at ambient and elevated temperatures and by chemical disinfection. The bacterium in its native environment was more resistant to adverse conditions, as compared with laboratory-grown organisms. Of the several chemical disinfectants acceptable to drinking water treatment and tested for Legionella inactivation, ozonation was the most efficient method. The C · t ' products indicated that free chlorine was superior to mono- and dichloramines. 相似文献
160.
Eric Esposito Douglas E Weidemann Jessie M Rogers Claire M Morton Erod Keaton Baybay Jing Chen Silke Hauf 《The EMBO journal》2022,41(15)
The mitotic checkpoint (also called spindle assembly checkpoint, SAC) is a signaling pathway that safeguards proper chromosome segregation. Correct functioning of the SAC depends on adequate protein concentrations and appropriate stoichiometries between SAC proteins. Yet very little is known about the regulation of SAC gene expression. Here, we show in the fission yeast Schizosaccharomyces pombe that a combination of short mRNA half‐lives and long protein half‐lives supports stable SAC protein levels. For the SAC genes mad2 + and mad3 +, their short mRNA half‐lives are caused, in part, by a high frequency of nonoptimal codons. In contrast, mad1 + mRNA has a short half‐life despite a higher frequency of optimal codons, and despite the lack of known RNA‐destabilizing motifs. Hence, different SAC genes employ different strategies of expression. We further show that Mad1 homodimers form co‐translationally, which may necessitate a certain codon usage pattern. Taken together, we propose that the codon usage of SAC genes is fine‐tuned to ensure proper SAC function. Our work shines light on gene expression features that promote spindle assembly checkpoint function and suggests that synonymous mutations may weaken the checkpoint. 相似文献