LDFF,the large molecular weight DNA fragmentation factor,is responsible for the large molecular weight DNA degradation during apoptosis in Xenopus egg extracts

DNA degradation is a biochemical hallmark in apoptosis. It has been demonstrated in many cell types that there are two stages of DNA fragmentation during the apoptotic execution. In the early stage, chromatin DNA is cut into large molecular weight DNA fragments, although the responsible nuclease(s) has not been recognized. In the late stage, the chromatin DNA is cleaved further into short oligonucleosomal fragments by a well-characterized nuclease in apoptosis,the caspase-activated DNase (CAD/DFF40). In this study, we demonstrate that large molecular weight DNA fragmentation also occurs in Xenopus egg extracts in apoptosis. We show that the large molecular weight DNA fragmentation factor (LDFF) is not the Xenopus CAD homolog XCAD. LDFF is activated by caspase-3. The large molecular weight DNA fragmentation activity of LDFF is Mg2+-dependent and Ca2+-independent, can occur in both acidic and neutral pH conditions and can tolerate 45℃ treatment. These results indicate that LDFF in Xenopus egg extracts might be a new DNase (or DNases) responsible for the large DNA fragmentation.

Molecular Cloning and Characterization of the Actin-depolymerizing Factor Gene in Gossypium barbadense

Sea Island cotton(Gossypium barbadense L.) has been highly valued in Verticillium wilt resistance and many fiber qualities including fiber length,strength,and fineness.To identify whether

A functional study of low molecular weight IgM from patients with autoimmune disease

High levels of low molecular weight (LMW) IgM in certain diseases are associated with clinical and laboratory indices which reflect the severity of the disease. These associations suggest that LMW IgM may play an important role in the immunopathogenesis of these diseases. To further approach the question concerning the functional activity of LMW IgM in disease, a panel of LMW IgM and high molecular weight (HMW) IgM preparations with or without rheumatoid factor (RF) activity were used to investigate their antibody binding activity and their effector function. It was found that LMW IgM-RF and HMW IgM-RF had a similar binding capacity to Fc fragment as there was no significant difference in the affinity index between them. It further showed that the rate of activation and total amount of utilization of complement by LMW IgM and HMW IgM was similar, although the mean fluorescence of C3 deposition by IgM-RF and HMW IgM-RF was slightly higher than that of LMW IgM-RF and other control RF antibodies. However, the current study demonstrated that LMW IgM had strong neutrophil activating properties when compared with HMW IgM. These findings suggest that one mechanism of LMW IgM contributing to the immunopathogenesis of RA may be due to the formation of circulating immune complex ( CIC) by LMW IgM with subsequent activation of neutrophils. Whether LMW IgM has other functional activity in disease is unclear and needs further investigation.

Molecular cloning,expression pattern and phylogenetic analysis of Guanine nucleotide exchange factor Vav2 in lamprey,Lampetra japonica

The Guanine nucleotide exchange factor Vav2（Vav2） is a member of the Vav family that serves as an important regulators for the Rho family of Ras-related GTPases. In the current study, an ortholog（Lj-Vav2） of Vav2 was identified in the lamprey（Lampetra japonica）. To elucidate the phylogenetic relationship of Vav2, the metazoan genome databases were analyzed to mine the ortholog of Vav. It was found that Vav2 genes were only existed in vertebrates and Lj-Vav2 was the original one found in agnathans. The evolutionary dynamics of conserved motifs of Vav2 were explored using combined amino acid sequence as markers, and it is revealed that the Calponin homology（CH） domain, Dbl-homologous（DH） domain, Pleckstrin homology（PH） domain, Cysteine-rich（C1）domains, Src homology 3（SH3） domains and Src homology 2（SH2） domain were conserved throughout the Vav2 gene family in vertebrates during gene evolution. Relative quantitative real-time PCR analysis showed that the LjVav2 was distributed in the heart, kidney, supraneural myeloid body, liver, gill and lymphocyte-like cells. The LjVav2 was found to be expressed in these tissues, and the level of which was upregulated in lymphocyte-like cells after the animal was stimulated with LPS. These results indicated that the Lj-Vav2 might be involved in the immune response of lymphocyte-like cells in lamprey. Meanwhile, our findings provided a foundation for further investigation of the function of Lj-Vav2 in the primary vertebrate.

Molecular mechanism of microRNA125 regulating human coagulation factor IX gene with nonsense mutation

Objective To construct human coagulation factorⅨmini-gene(Mini-h F9)and some nonsense mutants,detect the levels of the Mini-h F9 mRNA,and analyze the molecular mechanism of microRNA125 regulating F9gene with nonsense mutation.Methods Three nonsense mutants were obtained by using PCR mutagenesis to ana-

Relationship between microdeletion on Y chromosome and patients with idiopathic azoospermia and severe oligozoospermia in the Chinese

Objectives To evaluate the relationship between microdeletion or mutation on the Y chromosome and Chinese patients with idiopathic azoospermia and severe oligozoospermia and to establish a molecular detection method.Methods Microdeletion or mutation detection at the AZFa (sY84 and USP9Y), AZFb, AZFc/DAZ and SRY regions of the Y chromosome. Seventy-three azoospermia and 28 severe oligozoospermia patients were evaluated using PCR and PCR-SSCP techniques.Results Twelve of 101 patients (12%) with the AZFc/DAZ microdeletion were found, including 8 with azoospermia (11%) and 4 with severe oligozoospermia (14.3%), and 1 patient had a AZFb and AZFc/DAZ double deletion. No deletions in the AZFa or SRY regions were found. No deletions in AZFa, AZFb, AZFc/DAZ or SRY regions were found in 60 normal men who had produced one or more children.Conclusions Microdeletion on the Y chromosome, especially at its AZFc/DAZ regions, may be a major cause of azoospermia and severe oligozoospermia leading to male infertility in China. It is recommended that patients have genetic counseling and microdeletion detection on the Y chromosome before intracytoplasmic sperm injection.