Conversion of midbodies into germ cell intercellular bridges

Whereas somatic cell cytokinesis resolves with abscission of the midbody, resulting in independent daughter cells, germ cell cytokinesis concludes with the formation of a stable intercellular bridge interconnecting daughter cells in a syncytium. While many proteins essential for abscission have been discovered, until recently, no proteins essential for mammalian germ cell intercellular bridge formation have been identified. Using TEX14 as a marker for the germ cell intercellular bridge, we show that TEX14 co-localizes with the centralspindlin complex, mitotic kinesin-like protein 1 (MKLP1) and male germ cell Rac GTPase-activating protein (MgcRacGAP) and converts these midbody matrix proteins into stable intercellular bridge components. In contrast, septins (SEPT) 2, 7 and 9 are transitional proteins in the newly forming bridge. In cultured somatic cells, TEX14 can localize to the midbody in the absence of other germ cell-specific factors, suggesting that TEX14 serves to bridge the somatic cytokinesis machinery to other germ cell proteins to form a stable intercellular bridge essential for male reproduction.     

Isolation, cloning, and characterization of a novel phosphomannan-binding lectin from porcine serum

Mannan-binding protein (MBP) is a C-type serum lectin that is an important constituent of the innate immune defense because it activates the complement system via the lectin pathway. While the pig has been proposed to be an attractive source of xenotransplantable tissues and organs, little is known about porcine MBP. In our previous studies, phosphomannan, but not mannan, was found to be an effective inhibitor of the C1q-independent bactericidal activity of newborn piglet serum against some rough strains of Gram-negative bacteria. In contrast, the inhibitory activities of phosphomannan and mannan were very similar in the case of MBP-dependent bactericidal activity against rough strains of Escherichia coli K-12 and S-16. Based on these findings, we inferred that an MBP-like lectin with slightly or completely different carbohydrate binding specificity might exist in newborn piglet serum and be responsible for the C1q-independent bactericidal activity. Herein we report that a novel phosphomannan-binding lectin (PMBL) of 33 kDa under reducing conditions was isolated from both newborn and adult porcine serum and characterized. Porcine PMBL functionally activated the complement system via the lectin pathway triggered by binding with both phosphomannan (P-mannan) and mannan, which, unlike MBP, was effectively inhibited by mannose 6-phosphate- or galatose-containing oligosaccharides. Our observations suggest that porcine PMBL plays a critical role in the innate immune defense from the newborn stage to adult-hood, and the establishment of a newborn piglet experimental model for the innate immune system studies is a valuable step toward elucidation of the physiological function and molecular mechanism of lectin pathway.     

Replacement of nonmuscle myosin II-B with II-A rescues brain but not cardiac defects in mice

The purpose of these studies was to learn whether one isoform of nonmuscle myosin II, specifically nonmuscle myosin II-A, could functionally replace a second one, nonmuscle myosin II-B, in mice. To accomplish this, we used homologous recombination to ablate nonmuscle myosin heavy chain (NMHC) II-B by inserting cDNA encoding green fluorescent protein (GFP)-NMHC II-A into the first coding exon of the Myh10 gene, thereby placing GFP-NMHC II-A under control of the endogenous II-B promoter. Similar to B(-)/B(-) mice, most B(a*)/B(a*) mice died late in embryonic development with structural cardiac defects and impaired cytokinesis of the cardiac myocytes. However, unlike B(-)/B(-) mice, 15 B(a*)/B(a*) mice of 172 F2 generation mice survived embryonic lethality but developed a dilated cardiomyopathy as adults. Surprisingly none of the B(a*)/B(a*) mice showed evidence for hydrocephalus that is always found in B(-)/B(-) mice. Rescue of this defect was due to proper localization and function of GFP-NMHC II-A in place of NMHC II-B in a cell-cell adhesion complex in the cells lining the spinal canal. Restoration of the integrity and adhesion of these cells prevents protrusion of the underlying cells into the spinal canal where they block circulation of the cerebral spinal fluid. However, abnormal migration of facial and pontine neurons found in NMHC II-B mutant and ablated mice persisted in B(a*)/B(a*) mice. Thus, although NMHC II-A can substitute for NMHC II-B to maintain integrity of the spinal canal, NMHC II-B plays an isoform-specific role during cytokinesis in cardiac myocytes and in migration of the facial and pontine neurons.     

Waist-to-height ratio is an accurate and easier index for evaluating obesity in children and adolescents

Objectives: The present study aims to evaluate the accuracy of the index of waist‐to‐height ratio (WHTR), and proposed the optimal thresholds of WHTR in the definition of childhood overweight and obesity in a bi‐ethnic Chinese school‐aged population. Research Methods and Procedures: Overweight and obese were identified by BMI for age and gender in a random sample including 2055 Han and 2132 Uygur ethnic school‐aged children (8 to 18 years old). WHTR was calculated by waist circumference divided by height on the basis of standard anthropometric measurements. Receiver operating characteristic (ROC) curve analyses were performed to assess the accuracy of WHTR as a diagnostic test for childhood overweight and obesity, compared with waist circumference. The optimal thresholds of WHTR for defining overweight and obesity were recommended respectively by gender. The correlation between WHTR and age was analyzed and compared with BMI. Results: A‐values (area under curve) of WHTR for diagnosing overweight and obesity were both over 0.90 in both genders and better than those of waist circumference. A threshold of 0.445 was identified for overweight in both genders, with the sensitivity and specificity >0.80. The thresholds for defining obesity was 0.485 in boys and 0.475 in girls, both having the sensitivity and specificity >0.90. WHTR showed less association with age than BMI. Conclusions: WHTR is a simple, easy, accurate, and non‐age‐dependent index with high applicability to screening overweight and obesity in children and adolescents. The use of WHTR in the general childhood population has been justified by this study.     

Inhibition of tumor growth in mice by endostatin derived from abdominal transplanted encapsulated cells

Endostatin,a C-terminal fragment of collagen 18a,inhibits the growth of established tumorsand metastases in vivo by inhibiting angiogenesis.However,the purification procedures required for large-scale production and the attendant cost of these processes,together with the low effectiveness in clinicaltests,suggest that alternative delivery methods might be required for efficient therapeutic use of endostatin.In the present study,we transfected Chinese hamster ovary(CHO)cells with a human endostatin geneexpression vector and encapsulated the CHO cells in alginate-poly-L-lysine microcapsules.The release ofbiologically active endostatin was confirmed using the chicken chorioallantoic membrane assay.The encap-sulated endostatin-expressing CHO cells can inhibit the growth of primary tumors in a subcutaneous B 16tumor model when injected into the abdominal cavity of mouse.These results widen the clinical applicationof the microencapsulated cell endostatin delivery system in cancer treatment.     

Erwinia carotovora ssp. carotovora Infection Induced ＂Defense Lignin＂ Accumulation and Lignin Biosynthetic Gene Expression in Chinese Cabbage （Brassica rapa L. ssp. pekinensis）

Erwinia carotovora subsp, carotovora （Ecc） infects and causes soft rot disease in hundreds of crop species including vegetables, flowers and fruits. Lignin biosynthesis has been implicated in defensive reactions to injury and pathogen infection in plants. In this work, variations of lignin content and gene expression in the molecular interaction between Chinese cabbage and Ecc were investigated. H2O2 accumulation and peroxidase activity were detected by 3, 3＇- Dimethoxybenzidine staining at mocked and Ecc-inoculated sites of Chinese cabbage leafstalks. Klason lignin content in inoculated plants increased by about 7.84%, 40.37%, and 43.13% more than that of the mocked site at 12, 24 and 72 h after inoculation, respectively. Gas chromatography detected more p-coumaryl （H） and less coniferyl （G） and sinapyl （S） monolignins in leafstalks of Chinese cabbage. All three monomers increased in Ecc-infected leafstalks, and the Ecc-induced ＂defense lignin＂ were composed of more G and H monolignins, and less S monolignin. After searching the expressed sequence tags （EST） data of Chinese cabbage, 12 genes putatively encoding enzymes involved in lignin biosynthesis were selected to study their expression. All of these genes could be induced by mock inoculation and Ecc infection, while the gene expression lasted for several more hours in the infected samples than in mocked and untreated plants. Our results indicated that ＂defense lignin＂ was different from the developmental lignin in composition; G and S monolignins were significantly induced in plants in response to the soft rot Ecc; thus, lignin biosynthesis was differentially regulated and played a role in plant response to the soft rot Ecc.