Identification,expression and bioactivity of hexokinase in amphioxus: Insights into evolution of vertebrate hexokinase genes

Hexokinase family includes hexokinases I, II, III and IV, that catalyze the phosphorylation of glucose to produce glucose 6-phosphate. Hexokinase IV, also known as glucokinase, is only half size of the other types of hexokinases that contain two hexokinase domains. Despite the enormous progress in the study of hexokinases, the evolutionary relationship between glucokinase and other hexokinases is still uncertain, and the molecular processes leading to the emergence of hexokinases in vertebrates remain controversial. Here we clearly demonstrated the presence of a single hexokinase-like gene in the amphioxus Branchiostoma japonicum, Bjhk, which shows a tissue-specific expression pattern, with the most abundant expression in the hepatic caecum, testis and ovary. The phylogenetic and synteny analyses both reveal that BjHK is the archetype of vertebrate hexokinases IV, i.e. glucokinases. We also found for the first time that recombinant BjHK showed functional enzyme activity resembling vertebrate hexokinases I, II, III and IV. In addition, a native glucokinase activity was detected in the hepatic caecum. Finally, glucokinase activity in the hepatic caecum was markedly reduced by fasting, whereas it was considerably increased by feeding. Altogether, these suggest that Bjhk represents the archetype of glucokinases, from which vertebrate hexokinase gene family was evolved by gene duplication, and that the hepatic caecum plays a role in the control of glucose homeostasis in amphioxus, in favor of the notion that the hepatic caecum is a tissue homologous to liver.     

Ectopic cervical thymi and no thymic involution until midlife in naked mole rats

Immunosenescence is a hallmark of aging and manifests as increased susceptibility to infection, autoimmunity, and cancer in the elderly. One component of immunosenescence is thymic involution, age‐associated shrinkage of the thymus, observed in all vertebrates studied to date. The naked mole rat (Heterocephalus glaber) has become an attractive animal model in aging research due to its extreme longevity and resistance to disease. Here, we show that naked mole rats display no thymic involution up to 11 years of age. Furthermore, we found large ectopic cervical thymi in addition to the canonical thoracic thymus, both being identical in their cell composition. The developmental landscape in naked mole rat thymi revealed overt differences from the murine T‐cell compartment, most notably a decrease of CD4⁺/CD8⁺ double‐positive cells and lower abundance of cytotoxic effector T cells. Our observations suggest that naked mole rats display a delayed immunosenescence. Therapeutic interventions aimed at reversing thymic aging remain limited, underscoring the importance of understanding the cellular and molecular mechanisms behind a sustained immune function in the naked mole rat.     

Prophylactic effect of bestatin on the onset of invasive mole — clinical and fundamental studies

This study was performed to determine whether bestatin (Ubenimex) has clinical prophylactic effects on the onset of invasive mole and a direct inhibitory effect on the growth of hydatidiform molar cells. A total of 49 patients with hydatidiform mole treated at Nagoya University Hospital from 1984 to 1990 were randomly divided into two groups, a bestatin administered-group and a bestatin non-administered group. Patients in the bestatin group were given 30 mg of bestatin orally and daily for three months just after their molar deliveries. There was no significant difference in age, gravidity, parity and gestational weeks between the two groups. There was also no significant difference in the duration of human chorionic gonadotropin (hCG) negative conversion in patients without invasive mole between the two groups. However, the incidence of invasive mole in the bestatin group (2/25, 8%) was significantly lower than that of the non-bestatin group (7/24, 29.2%). Nevertheless, there was no significant difference between the two groups in such immunological parameters as PHA skin test, PPD skin test, PHA stimulation index (PHA-SI), white blood cell (WBC) count lymphocytes % per WBC, OKT 3% per lymphocytes, OKT 4% per lymphocytes, OKT4/OKT8 and Leu 11% per lymphocytes. In vitro studies were performed with primary cultured hydatidiform moles. The result was that bestatin inhibited the secretion of hCG and³H-thymidine uptake of hydatidiform molar cells. Thus, a possibility was suggested that bestatin directly inhibits the growth of hydatidiform molar cells and prevents the onset of invasive mole.     

Differential effects of carotenoids on lipid peroxidation due to membrane interactions: X-ray diffraction analysis

The biological benefits of certain carotenoids may be due to their potent antioxidant properties attributed to specific physico-chemical interactions with membranes. To test this hypothesis, we measured the effects of various carotenoids on rates of lipid peroxidation and correlated these findings with their membrane interactions, as determined by small angle X-ray diffraction approaches. The effects of the homochiral carotenoids (astaxanthin, zeaxanthin, lutein, β-carotene, lycopene) on lipid hydroperoxide (LOOH) generation were evaluated in membranes enriched with polyunsaturated fatty acids. Apolar carotenoids, such as lycopene and β-carotene, disordered the membrane bilayer and showed a potent pro-oxidant effect (> 85% increase in LOOH levels) while astaxanthin preserved membrane structure and exhibited significant antioxidant activity (40% decrease in LOOH levels). These findings indicate distinct effects of carotenoids on lipid peroxidation due to membrane structure changes. These contrasting effects of carotenoids on lipid peroxidation may explain differences in their biological activity.     

Speciation and adaptive radiation of subterranean mole rats, Spalax ehrenbergi superspecies, in Jordan

The major initial mechanism of speciation in subterranean blind mole rats, Spalacidae, is chromosomal, primarily through Robertsonian rearrangements. Here we highlight another scenario of chromosomal rearrangement leading to ecological speciation and adaptive radiation apparently initiated by pericentric inversions and genie divergence to different ecologies in mole rats in Jordan. We analysed karyotype, allozyme, size and ecological diversity across the range of mole rats in Jordan from mesic Irbid in the north to xeric Wadi Musa (Petra region) in the south, a transect of 250 km. We examined mole rats for chromosome ( N =71), size ( N =76), and allozyme ( N =67) diversities, encoded by 32 loci, in 12 populations of the Spalax ehrenbetgi superspecies in Jordan. By a combination of chromosome morphology, genetic distance, body size and ecogeography, we identified four new putative biological species. All species (except two animals in Madaba) share 2 n = 60 but vary in chromosome morphology, caused by pericentric inversions and/or centromeric shifts. The 'north Moav' species is karyotypically polymorphic for 2 n (2 n = 60; including locally also two animals with 2 n = 62). The distribution of the four species is associated with ecogeographical different domains and climatic diversity. Genetic diversity indices were low, but like chromosome arms (NFa) were positively correlated with aridity stress. Discriminant analysis correctly classified 91% of the individuals into the four species utilizing combinatorially chromosome, allozyme and size diversities. It is hypothesized that mole rat evolution underground is intimately associated with climatic diversity stress above ground.     

中国大鲵肌肉蛋白肽对BPA诱导小鼠精子发生障碍的治疗作用及其机制研究

摘要 目的：研究中国大鲵肌肉蛋白肽（The protein and peptide extracts from muscles of Chinese giant salamanders,SP）对双酚A（bisphenol A,BPA）诱导的小鼠生精障碍的保护作用,并初步探讨其作用机制。方法：40只C57BL/6 雄性小鼠分为四组,分别为Control组、BPA组、BPA+CS（Compound Substance）组、BPA+SP组。BPA组使用50 mg/kg/d的BPA腹腔注射,BPA溶解于玉米油;Control组只腹腔注射玉米油。BPA+CS组灌胃其他有利于生精壮阳的复合物用作对照,复合物溶解于生理盐水中;BPA+SP组灌胃上述复合物联合大鲵肌肉蛋白肽,以上灌胃剂量均4 g/kg/d。连续造模28天,期间每周测定小鼠体重,造模结束后测定睾丸体积、睾体比,取附睾精子使用CASA计算机辅助分析系统测定精子数目、精子活力,ELISA法测定血清睾酮含量,HE染色、TUNEL染色分析睾丸组织病理学,最后采用免疫荧光染色及Western blotting分析转移相关基因2（MTA2）的表达情况、油红O染色观察支持细胞体内、体外吞噬作用。结果：与对照组比较,BPA组睾丸体积（P<0.05）、睾丸重量（P<0.05）、睾体比（P<0.05）、精子数目（P<0.05）、精子活力（P<0.05）、睾酮含量（P<0.01）均显著降低,睾丸组织形态受损（P<0.05）、生精细胞凋亡增多（P<0.01）、MTA2表达量降低（P<0.01）、支持细胞吞噬功能减弱（P<0.01）;BPA+CS组较BPA组无明显变化,BPA+SP组以上变化显著改善（P<0.05）。结论：大鲵肌肉蛋白肽对BPA诱导的小鼠生精功能障碍有明显的保护作用,作用机制可能与干预MTA2表达进而增强支持细胞的吞噬作用相关。     

Genome‐specific histories of divergence and introgression between an allopolyploid unisexual salamander lineage and two ancestral sexual species

Quantifying introgression between sexual species and polyploid lineages traditionally thought to be asexual is an important step in understanding what drives the longevity of putatively asexual groups. Here, we capitalize on three recent innovations—ultraconserved element (UCE) sequencing, bioinformatic techniques for identifying genome‐specific variation in polyploids, and model‐based methods for evaluating historical gene flow—to measure the extent and tempo of introgression over the evolutionary history of an allopolyploid lineage of all‐female salamanders and two ancestral sexual species. Our analyses support a scenario in which the genomes sampled in unisexual salamanders last shared a common ancestor with genomes in their parental species ～3.4 million years ago, followed by a period of divergence between homologous genomes. Recently, secondary introgression has occurred at different times with each sexual species during the last 500,000 years. Sustained introgression of sexual genomes into the unisexual lineage is the defining characteristic of their reproductive mode, but this study provides the first evidence that unisexual genomes have undergone long periods of divergence without introgression. Unlike other sperm‐dependent taxa in which introgression is rare, the alternating periods of divergence and introgression between unisexual salamanders and their sexual relatives could explain why these salamanders are among the oldest described unisexual animals.     

Biomimeitc Design of a Stubble-Cutting Disc Using Finite Element Analysis

Mole rat (Scaptochirus moschatus), a soil-burrowing mammal, can efficiently dig soil using its fore claws. The profile curves of its claw toe provide excellent structure for digging. In this paper, a biomimetic stubble-cutting disc was designed by learning from the geometrical characteristics of the mole rat claw toes. To compare the structural strength and working efficiency of the biomimetic disc and the conventional stubble-cutting disc, three-dimensional (3D) models of the discs were built and numerical analyzed in ABAQUS. In the dynamic soil cutting model, soil was modeled as an elastic-plastic material with elastic parameters, including Young's modulus, Poisson's ratio and Drucker-Prager criterion, which were obtained from triaxial tests. A general contact algorithm was used to simulate the interaction between rotary disc and soil. In FEA models, for the combined action of normal and friction stresses, the stress on the biomimetic disc is 34.33% lower than that of the conventional disc. For only the normal stress, the stress on the biomimetic disc is 22.64% lower than that on the conventional one. The magnitude of soil stress in biomimetic disc cutting model is 6.87% higher than that in conventional disc. The FEA results indicate that the biomimetic disc performs better in structural strength and cutting efficiency.     

Mechanism of pH-triggered collapse of phosphatidylethanolamine liposomes stabilized by an ortho ester polyethyleneglycol lipid

The mechanism of pH-triggered destabilization of liposomes composed of a polyethyleneglycol-orthoester-distearoylglycerol lipid (POD) and phosphatidyl ethanolamine (PE) has been studied using an ANTS/DPX leakage and a lipid-mixing assay. We developed a kinetic model that relates POD hydrolysis to liposome collapse. This minimum-surface-shielding model describes the kinetics of the pH-triggered release of POD/PE liposomes. In the model, when acid-catalyzed hydrolysis lowers the mole percentage of POD on the liposome surface to a critical level, intervesicular lipid mixing is initiated, resulting in a burst of contents release. Two phases of content leakage are observed: a lag phase and a burst phase. During the lag phase, less than 20% of liposomal contents are released and the leakage begins to accelerate when approaching to the transition point. During the burst phase, the leakage rate is dependent on interbilayer contact. The burst phase occurs when the surface density of the PEG lipid is 2.3 +/- 0.6 mol%, regardless of the pH. Vesicles containing 4 mol% of a pH-insensitive PEG-lipid conjugate and 10% POD did not leak contents or collapse at any pH. These data are consistent with the stalk theory to describe the lamellar-to-inverted hexagonal phase transition and set a lower bound of approximately 16 PE lipids on the external monolayer as the contact site required for lipid mixing between two bilayers.