Immunohistochemical studies on peptide- and amine-containing endocrine cells and nerves in the gut and the rectal gland of the ratfish Chimaera monstrosa

Summary The occurrence and distribution of endocrine cells and nerves were immunohistochemically demonstrated in the gut and rectal gland of the ratfish Chimaera monstrosa (Holocephala). The epithelium of the gut mucosa revealed open-type endocrine cells exhibiting immunoreactivity for serotonin (5HT), gastrin/cholecystokinin (CCK), pancreatic polypeptide (PP)/FMRFamide, somatostatin, glucagon, substance P or gastrin-releasing peptide (GRP). The rectum contained a large number of closed-type endocrine cells in the basal layer of its stratified epithelium; the majority contained 5HT- and GRP-like immunoreactivity in the same cytoplasm, whereas others were immunoreactive for substance P. The rectal gland revealed closed-type endocrine cells located in the collecting duct epithelium. Most of these contained substance P-like immunoreactivity, although some reacted either to antibody against somatostatin or against 5HT. Four types of nerves were identified in the gut and the rectal gland. The nerve cells and fibers that were immunoreactive for vasoactive intestinal peptide (VIP) and GRP formed dense plexuses in the lamina propria, submucosa and muscular layer of the gut and rectal gland. A sparse network of gastrin- and 5HT-immunoreactive nerve fibers was found in the mucosa and the muscular layer of the gut. The present study demonstrated for the first time the occurrence of the closed-type endocrine cells in the mucosa of the rectum and rectal gland of the ratfish. These abundant cells presumably secrete 5HT and/or peptides in response to mechanical stimuli in the gut and the rectal gland. The peptide-containing nerves may be involved in the regulation of secretion by the rectal gland.     

Dietary supplementation with docosahexaenoic acid,but not with eicosapentaenoic acid,reduces host resistance to fungal infection in mice

The effect of dietary docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) on host resistance to Paracoccidioides brasiliensis infection was investigated. Mice fed palm oil supplemented with DHA showed reduced antifungal activity in the spleen and liver, as compared with mice fed palm oil or soybean oil without supplementation with DHA. Mice fed DHA-supplemented soybean oil also showed reduced antifungal activity in the liver, but the extent of reduction was less profound. This reduction in antifungal activity was not observed with EPA-supplemented palm or EPA-supplemented soybean oil. These results suggest that two factors, DHA and palm oil in combination, are involved in reducing the host resistance. DHA-enriched palm oil was also responsible for an increase in DHA concentration and a marked decrease in arachidonic acid content in the spleen and liver. However, this group did not show elevated spleen and liver phospholipid hydroperoxide levels compared with the other groups, excluding the possibility that the reduction in antifungal activity observed with DHA-enriched palm oil is due to acceleration of in vivo lipid peroxidation. Greater infection-induced increases in spleen and serum interferon-gamma concentrations were observed in mice fed DHA-enriched palm oil compared with the other groups.     

Neonatal tolerance induction in the thymus to MHC-class II-associated antigens. II. Significance of MHC antigens in anti-Mls tolerance

Specificity of anti-Mlsa tolerance induced in BALB/c (H-2d, Mlsb) neonates was investigated by a popliteal lymph node (PLN)-swelling assay for the local graft-versus-host (GVH) reaction by injecting tolerant thymus cells into the footpads of several types of F1 hybrid mice. When thymus cells were obtained from 1-week-old normal BALB/c, they evoked enlargement of PLNs of (BALB/c X DBA/2)F1 (H-2d, Mlsb/a) [CDF1] recipients and of other hybrid recipients, heterozygous in Mlsa,c,d alleles, irrespective of the major histocompatibility complex (MHC) haplotypes. The same thymus cells did not cause the response in MHC-heterozygous F1 hybrids when the hybrids were homozygous in Mlsb, identical with BALB/c mice. Therefore, the PLN response to Mls antigens, known to be closely associated with MHC-class II antigens, was not directed to the class II antigens themselves. This enabled us to examine the effects of MHC on tolerance induction to the Mls antigens. When BALB/c neonates were injected with CDF1 bone marrow cells, complete tolerance to Mlsa-H-2d antigens of CDF1 cells was induced in the thymus, while responsiveness to Mlsa antigens in the context of H-2k and H-2b antigens, was not affected. This indicates MHC-restriction of neonatal tolerance to Mls antigens. Furthermore, when Mls and H-2-heterozygous (BALB/c X AKR)F1 (H-2d/k, Mlsb/a) bone marrow cells served as the tolerogen, thymus cells of BALB/c neonates were also tolerized to Mlsa-H-2k antigens as well as to Mlsa-H-2d antigens, which suggests the involvement of MHC, probably class II antigens of tolerance-inducing cells.     

Late Quaternary Environmental and Human Impacts on the Mitochondrial DNA Diversity of Four Commensal Rodents in Myanmar

Journal of Mammalian Evolution - We addressed the spatiotemporal characteristics of four commensal rodent species occurring in Myanmar in comparison with other areas of the Indo-Malayan region. We...     

Refeeding with a standard diet after a 48-h fast elicits an inflammatory response in the mouse liver

Unhealthy eating behaviors increase the risk of metabolic diseases, but the underlying mechanisms are not fully elucidated. Because inflammation contributes to the pathogenesis of metabolic diseases, it is important to understand the effects of unhealthy eating on the inflammatory state. The objective of our present study was to address the effects of a fasting–refeeding regime, a model of irregular eating, on the hepatic inflammatory responses in mouse. The animals were fasted for 48 h and then refed either a standard or low-carbohydrate/high-fat diet. Inflammatory gene expression in the liver was then sequentially measured for the first 17 h after initiation of refeeding. To assess the roles of dietary carbohydrates and toll-like receptor 2 (TLR2) in the refeeding-induced inflammatory changes, gene expression levels in mice refed only carbohydrates (α-corn starch and sucrose) at different doses and in TLR2-deficient mice refed a standard diet were also analyzed. Refeeding with a standard diet increased the liver expression of Tlr2, proinflammatory mediators (Cxcl10, Cxcl1, Cxcl2, Icam-1) and negative regulators of TLR-signaling (A20 and Atf3). These increases were attenuated in mice refed a low-carbohydrate/high-fat diet. Refeeding only α-corn starch and sucrose also increased the expression of these inflammatory pathway genes depending on the doses. TLR2 deficiency significantly attenuated the refeeding-induced increase in the liver expression of Cxcl10, Cxcl1, Icam-1 and A20. These findings suggest that an irregular eating behavior can elicit a liver inflammatory response, which is at least partly mediated by TLR2, and that dietary carbohydrates play critical roles in this process.     

Cold Shock of Germinating Bacillus subtilis Spores

Susceptibility of germinating spores of Bacillus subtilis to a rapid chilling was examined by viable countings. Dormant spores were quite resistant to the cold shock but the spores, immediately upon germination, lose viability almost completely by the same treatment. The presence of divalent cation, magnesium, calcium or manganese, in a buffer to which the germinating spores were suspended, markedly protected the cells from the death by the cold shock effect. When the shocked cells were incubated in the buffer containing casein acid hydrolyzate, glucose and magnesium ion for short period of time, a remarkable increase in viable counts was observed. The existence of two critical temperature zones, which were determined by the initial temperature of cell suspension, was confirmed in the cold shock of germinating spores.     

Rapid PaperMicrobial Oxygenation of Organo-metallic Bissulfides Leading to Formation of Planar Chirality and C2 Symmetry

1,2-Bis(methylthiomethyl)ferrocene (3) was oxidized by Corynebacterium equi IFO 3730 to give monosulfoxide 4 in two diastereomeric forms with (1S,2R,S_S) and (1S,2R,R_S) configurations in a ratio of 4:1, while 1,1′-bis(methylthiomethyl)ferrocene (5) was oxidized by Penicillium frequentans IFO 5692 to (R)-monosulfoxide 6 and then preferentially to (R,R)-bissulfoxide 7. Thus, the bacterial monooxygenase generated specific planar chirality in the metallocenic monosulfoxide, and the fungal enzyme formed C₂ symmetry in the bissulfoxide.     

The First and Second Dissociation Constants of Subtilisin BPN′-Plasminostreptin Complex Determined by a Polarographic Method,and the Effects of pH on Them

A polarographic method based on the Brdi?ka current (the polarographic catalytic hydrogen evolution current produced by proteins in the presence of cobalt salts) was applied to direct titration of subtilisin BPN′ (S.BPIST) with plasminostreptin (PS) at a concentration level of 10”⁸ m. The first and second dissociation constants of the S.BPN-PS complex were determined by fitting theoretical curves to the titration data, in which the multiple equilibria involving microscopically distinct forms of S.BPN-PS complex were taken into account. The intrinsic free energy change in the first binding of S.BPN′ to dimeric PS was larger than that in the second binding. The dependence of the microscopic dissociation constants of S.BPN′-PS complex on pH indicates the participation of ionizable groups of pK_a 8.0 and 9.4 in the complex formation. The repulsive effect between negatively charged molecules of S.BPN′ and PS in the complex formation at elevated pH is suggested.