Multifunctions of the upper lip and a ventral reflecting organ in a bioluminescent ostracod Vargula hilgendorfii (Müller, 1890)

Multifunctions of the upper lip in a bioluminescent myodocopid Vargula hilgendorfii were studied by video observation and histological method. The localization of luciferin and luciferase gland cells within the upper lip was partly successful. Two long protrusions of the upper lip, both of V. hilgendorfii and a non-luminescent species of the same family, immediately anterior to the mouth, were found to show very flexible movement especially while eating, as if smearing on the food surface a secretion from the protrusions (glands), which may support the hypothesized secretion of digestive enzymes from the upper lip. This hypothesis is further supported by the new finding of a pair of ducts which connect the basal part of the upper lip with the posterior digestive duct (stomach). Comparative studies of V. hilgendorfii with several sympatric non-luminescent species of the same family have also revealed that it has a characteristic reflecting organ immediately posterior to the anus. It is a conical small protrusion, as if dangling from the ventral edge of the abdomen at the apex of the cone. It is observable only in live specimens, when the furca, which is located outwardly to the organ, is sufficiently transparent. When illuminated, the reflecting organ reflects the distinct light. The diameter of the mirror (chemical composition provisionally analyzed) is about 6–8% of the carapace length. The organ develops from the very first stage of its ontogeny without reference to sex, which suggests that the function may be related to intraspecific signaling or predatory deterrence.     

Salicylate inhibits fimbriae mediated HEp-2 cell adherence of and haemagglutination by enteroaggregative Escherichia coli

Enteroaggregative Escherichia coli (EAggEC) are associated with both acute and persistent diarrhoea in children. Bowel colonisation due to fimbrial adherence factors appears to play a major role in the disease process. In this study, we investigated the effect of sodium salicylate and 5-aminosalicylic acid on adherence of a type strain and 40 clinical isolates of EAggEC to HEp-2 cells and erythrocytes from different species. Growth in the presence of 10 mM salicylate resulted in markedly decreased adherence to tissue culture cells with 33/40 (82.5%) isolates, and was also associated with inhibition of haemagglutination in 20/33 (60.6%) isolates. Complete or partial inhibition of adherence was also seen in two of five isolates showing localised adherence and three of five isolates with diffuse adherence. Decrease in adherence was associated with decreased or absent expression of fimbriae in 28/40 (70%) of the EAggEC isolates, although production of outer membrane proteins was not affected. Salicylates appear to inhibit adherence mediated by fimbrial adhesins.     

Molecular Dynamics Study of High Temperature Phase-Separation in a H2O/N2 Mixture with Exp-6 Interactions

Abstract

Equimolar H₂O/N₂ fluid mixture was studied by molecular dynamics simulations for NVT ensemble. Calculations were performed with the modified Buckingham (exp-6) potentials at T = 2000 K. Particular attention was given to the phase separation at very high pressures relevant to a detonation environment. Calculations of pair correlation functions and local mole fractions clearly indicated the occurrence of the fluid separation into N₂-rich and H₂O-rich phase. The density at the phase boundary between homogeneous and inhomogeneous phase-separated state was determined to be p = 1.35 g/cm³ on the basis of the static cross correlation factor which is defined by the sum of the local mole fractions. The ratio of the self-diffusion coefficients of N₂ and H₂O at p < 1.35 g/cm³ was found to be approximately equal to the value predicted by the kinetic theory of the ideal gas, whereas the ratio was close to unity at the phase-separated state (p > 1.35 g/cm³). In addition, two distinctive behaviors of the system could be observed for the relaxation from the initial uniform mixture to the phase-separated fluid: at lower densities (1.35 < p < 2.0 g/cm³) the fluid mixture began to relax into the phase-separated system without obvious incubation time, while clear incubation period was associated for the separation at higher densities. During this incubation period, discontinuous jumps in the mean square displacements were found.     

Cross-talk between thyroid hormone receptor and liver X receptor regulatory pathways is revealed in a thyroid hormone resistance mouse model

Hypercholesterolemia is found in patients with hypothyroidism and resistance to thyroid hormone. In this study, we examined cholesterol metabolism in a thyroid hormone receptor beta (TR-beta) mutant mouse model of resistance to thyroid hormone. Whereas studies of cholesterol metabolism have been reported in TR-beta knock-out mice, generalized expression of a non-ligand binding TR-beta protein in this knock-in model more fully recapitulates the hypothyroid state, because the hypothyroid effect of TRs is mediated by the unliganded receptor. In the hypothyroid state, a high cholesterol diet increased serum cholesterol levels in wild-type animals (WT) but either did not change or reduced levels in mutant (MUT) mice relative to hypothyroidism alone. 7alpha-Hydroxylase (CYP7A1) is the rate-limiting enzyme in cholesterol metabolism and mRNA levels were undetectable in the hypothyroid state in all animals. triiodothyronine replacement restored CYP7A1 mRNA levels in WT mice but had minimal effect in MUT mice. In contrast, a high cholesterol diet markedly induced CYP7A1 levels in MUT but not WT mice in the hypothyroid state. Elevation of CYP7A1 mRNA levels and reduced hepatic cholesterol content in MUT animals are likely because of cross-talk between TR-beta and liver X receptor alpha (LXR-alpha), which both bind to a direct repeat + 4 (DR+4) element in the CYP7A1 promoter. In transfection studies, WT but not MUT TR-beta antagonized induction of this promoter by LXR-alpha. Electromobility shift analysis revealed that LXR/RXR heterodimers bound to the DR+4 element in the presence of MUT but not WT TR-beta. A mechanism for cross-talk, and potential antagonism, between TR-beta and LXR-alpha is proposed.     

Q-FISH Measurement of Hepatocyte Telomere Lengths in Donor Liver and Graft after Pediatric Living-Donor Liver Transplantation: Donor Age Affects Telomere Length Sustainability

Along with the increasing need for living-donor liver transplantation (LDLT), the issue of organ shortage has become a serious problem. Therefore, the use of organs from elderly donors has been increasing. While the short-term results of LDLT have greatly improved, problems affecting the long-term outcome of transplant patients remain unsolved. Furthermore, since contradictory data have been reported with regard to the relationship between donor age and LT/LDLT outcome, the question of whether the use of elderly donors influences the long-term outcome of a graft after LT/LDLT remains unsettled. To address whether hepatocyte telomere length reflects the outcome of LDLT, we analyzed the telomere lengths of hepatocytes in informative biopsy samples from 12 paired donors and recipients (grafts) of pediatric LDLT more than 5 years after adult-to-child LDLT because of primary biliary atresia, using quantitative fluorescence in situ hybridization (Q-FISH). The telomere lengths in the paired samples showed a robust relationship between the donor and grafted hepatocytes (r = 0.765, p = 0.0038), demonstrating the feasibility of our Q-FISH method for cell-specific evaluation. While 8 pairs showed no significant difference between the telomere lengths for the donor and the recipient, the other 4 pairs showed significantly shorter telomeres in the recipient than in the donor. Multiple regression analysis revealed that the donors in the latter group were older than those in the former (p = 0.001). Despite the small number of subjects, this pilot study indicates that donor age is a crucial factor affecting telomere length sustainability in hepatocytes after pediatric LDLT, and that the telomeres in grafted livers may be elongated somewhat longer when the grafts are immunologically well controlled.