Temperature dependencies of the optical rotation and size exclusion chromatography with low-angle laser light scattering (SEC−LALLS) were performed on the sonicated K+, κ-carrageenan in KCl salt solutions. The molecular weights were measured at the temperatures of the coil, helix, and coil−helix transition regions. The temperature at each region was determined by the optical rotation experiment. In a solution of low KCl salt concentration, the molecular weights did not change at any of the temperatures investigated. In this case, no hysteresis in the temperature dependence curve of optical rotation was observed. On the other hand, when the salt concentration increased, the molecular weight increased according to the transition from the coil to a helical conformation. In this case, a hysteresis was observed in the optical rotation curve. Moreover, the greater the increase in the KCl concentration, the greater the increase in molecular weight. These results indicate the existence of multiple conformational states for κ-carrageenan that depend upon the solution conditions. That is, κ-carrageenan makes a conformational transition from the coil to a single helical conformation at low KCl salt concentrations. However, κ-carrageenan takes on a helical conformation with a dimerized molecular weight when the salt concentration increases. These dimerized helical molecules further aggregate when the salt concentration increases further.

AF5q31 (also called MCEF) was identified by its involvement in chromosomal translocation with the gene MLL (mixed lineage leukemia), which is associated with infant acute lymphoblastic leukemia. Several potential roles have been proposed for AF5q31 and other family genes, but the specific requirements of AF5q31 during development remain unclear. Here, we show that AF5q31 is essential for spermatogenesis. Although most AF5q31-deficient mice died in utero and neonatally with impaired embryonic development and shrunken alveoli, respectively, 13% of AF5q31-deficient mice thrived as wild-type mice did. However, the male mice were sterile with azoospermia. Histological examinations revealed the arrest of germ cell development at the stage of spermiogenesis, and virtually no spermatozoa were seen in the epididymis. AF5q31 was found to be preferentially expressed in Sertoli cells. Furthermore, mutant mice displayed severely impaired expression of protamine 1, protamine 2, and transition protein 2, which are indispensable to compact the haploid genome within the sperm head, and an increase of apoptotic cells in seminiferous tubules. Thus, AF5q31 seems to function as a transcriptional regulator in testicular somatic cells and is essential for male germ cell differentiation and survival. These results may have clinical implications in the understanding of human male infertility.Chromosomal translocation is one of the common pathogenic mechanisms in various human malignancies, particularly in leukemias and lymphomas, and genes located at the breakpoints are involved in disease pathogenesis (21,59,60). The mixed lineage leukemia gene MLL (also called HRX, HTRX, and ALL-1) is frequently targeted by chromosomal rearrangements and is associated with clinically aggressive lymphoid and myeloid leukemias which are particularly prevalent in infant leukemias and treatment-related secondary leukemias (2,18,24,64). MLL located on 11q23 is a human homologue of Drosophila trithorax, has a SET domain that normally functions as histone methyltransferase, and is assembled into a supermultiprotein complex with additional chromatin-remodeling components (45,50,70). Importantly, most of the leukemic variants of MLL lack the SET domain (7). In Drosophila, genetic evidence suggests that Trithorax controls the expression of homeobox (Hox) genes and regulates embryogenesis (39,44,47). In MLL-deficient mice, Hox gene expression initiates normally but is not maintained after 9.5 days postcoitus (dpc), demonstrating the importance of MLL in the maintenance of Hox gene expression (72,73). Hox genes also play an important role in hematopoietic differentiation, and their expression levels are upregulated in the human leukemias carrying MLL rearrangements (1). An unusual feature of MLL fusion proteins is the large number and diversity of heterologous proteins that fuse with MLL. To date, the MLL locus has been found to be translocated to approximately 40 different genetic loci and at least 30 of the partner genes have been characterized (13,31). The fun...

Two endothelium-derived factors, endothelin (ET), a vasoconstrictor, and vascular endothelial growth factor (VEGF), an angiogenic factor are thought to be involved in the pathogenesis of diabetic vascular complications. The aim of this study was to determine the effects of an angiotensin II type I (AT-1) receptor antagonist and an ACE inhibitor on the pathogenesis of VEGF and ET-1-mediated kidney disease in STZ-induced diabetic rats. Two days after STZ administration, diabetic rats were treated for 8 weeks with enalapril maleate, an ACE inhibitor, candesartan cilexetil, an AT-1 receptor antagonist, or saline. Urinary albumin and N-acetyl beta-D glucosaminidase (NAG) excretion as well as the VEGF protein content in the kidney were all found to be elevated in diabetic rats. Administration of enalapril maleate or candesartan cilexetil decreased the level of microalbuminuria and NAG excretion in diabetic rats. Administration of enalapril maleate also suppressed the elevated renal VEGF protein content in these animals while candesartan cilexetil treatment had no effect. Serum ET-1 and VEGF levels were unchanged by these treatments. These data support a role for AT-1 receptor antagonists and ACE inhibitors in the prevention of diabetic nephropathy, and suggest that the former may work by reducing renal VEGF levels.

The larvae of the pit-making antlion Myrmeleon bore Tjeder live in open sand in riverbeds with a substratum consisting of various particle sizes. We analyzed the spatial distribution of their pits in a sandy floodplain to determine their larval and adult responses to the heterogeneous substrate. The spatial distribution pattern of their pits had an aggregated distribution, and there was a significant positive correlation between pit density and the ratio of medium-size sand particles to total weight of sand. We examined the size of sand particles selected in the larval pit-building behavior and the oviposition behavior of the adult. Both larvae and adults selected medium-size sand particles. The larvae of M. bore are relatively sedentary predators and rarely move great distances. Thus, the present results suggest that habitat selection by adult females is a major factor causing the aggregative distribution of the pits.