Fibrillation of tropoelastin induced by proteoglycan.

Electrostatic interaction between tropoelastin, the native precursor of elastin, and proteoglycan results in tropoelastin fibrillation. The finding suggests a possible involvement of proteoglycans in elastogenesis.     

The emerging roles for the chromatin structure regulators CTCF and cohesin in neurodevelopment and behavior

Recent genetic and technological advances have determined a role for chromatin structure in neurodevelopment. In particular, compounding evidence has established roles for CTCF and cohesin, two elements that are central in the establishment of chromatin structure, in proper neurodevelopment and in regulation of behavior. Genetic aberrations in CTCF, and in subunits of the cohesin complex, have been associated with neurodevelopmental disorders in human genetic studies, and subsequent animal studies have established definitive, although sometime opposing roles, for these factors in neurodevelopment and behavior. Considering the centrality of these factors in cellular processes in general, the mechanisms through which dysregulation of CTCF and cohesin leads specifically to neurological phenotypes is intriguing, although poorly understood. The connection between CTCF, cohesin, chromatin structure, and behavior is likely to be one of the next frontiers in our understanding of the development of behavior in general, and neurodevelopmental disorders in particular.     

Age-related differences in the effect of in vivo administration of indomethacin on hemopoietic cell lineages of the spleen and bone marrow of mice

During 21 days of indomethacin treatment, erythroid cells in the spleens of both young adult and older mice, and in the bone marrow of young adult mice, were increased significantly early, in treatment, relative to age-matched control organs, and remained high throughout treatment. During drug exposure, the numbers of myeloid cells in young adult bone marrow, but not spleen, were reduced, but in older mice these cells were elevated in both organs. Lymphoid cells in the young adult and older mouse spleens decreased and increased, respectively, during treatment, but were unchanged and decreased, respectively, in the bone marrow of young adult and older mice. Monocytemacrophage cells in the spleen were elevated but unchanged in the bone marrow of both age groups. During 14 days of indomethacin treatment of houng adult mice, the proportions of precursor cells in DNA synthesis of only the splenic erythroid lineage were increased. Thus, the major hemopoietic lineages in both the bone marrow and spleen are affected by exposure to indomethacin in a time-dependent and age-dependent manner. For all lineages studied, those of the bone marrow were least disturbed, and/or were first to recover, even during continued drug exposure.     

A morphometric study of spermatogenesis in the testes of mice of a senescence accelerated strain

The morphometric parameters of spermatogenic cells in a mouse strain prone to accelerated senescence (SAM-P), a novel murine model of spontaneously promoted aging, were compared with those of a SAM resistant strain (SAM-R) after birth until 40 weeks (mean life span of SAM-P). A mixture of gonocytes and spermatogonia were present in the testis in 1-week-old mice, and no gonocytes were observed in 2-week-old mice. At 6 weeks of age, the absolute number of spermatogonia in SAM-P was 27% greater than that in SAM-R, whereas the cell number in 40-week-old SAM-P was 17% less than in SAM-R. Primary spermatocytes were first observed in 3-week-old animals, and the cell numbers in SAM-P at 3, 5 and 6 weeks were 78%, 31% and 25%, respectively, greater than in SAM-R, whereas the cell number in SAM-P at 40 weeks was 30% less than SAM-R. Round spermatids were first observed in all SAM-P at 4 weeks old, but 20% of SAM-r had no spermatids and the rest had only a few. At 5 and 6 weeks old, the absolute numbers of round spermatids in SAM-P was about 34% and 41%, respectively, greater than in SAM-R, whereas the cell number in 40-week-old SAM-P was about 34% less than SAM-R. These results indicate that testicular maturation begins at an earlier age in SAM-P than SAM-R. Furthermore, at the age of 40 weeks signs of testicular deterioration are evident in SAM-P mice only     

Sex differences in human circadian rhythms: Intrinsic periods and sleep fractions

Summary The period of freerunning circadian rhythms is significantly shorter and the fraction of sleep is significantly larger in human females than in males, as long as the rhythms run internally synchronized. The sex difference in the period could be a property either of the whole circadian system or of only one of the oscillators in a multi-oscillator system. The sex difference in the sleep fraction could be a fixed property of the sleep-wake rhythm or could depend on interactions in the multi-oscillator system. To investigate these questions, a sample of 33 long-term experiments, in which the rhythms ran internally synchronized in one section and internally desynchronized in another section, were analyzed. The periods of rhythms in rectal temperature were different in females and males during internal synchronization, but became identical during internal desynchronization. In contrast, sex differences in sleep-wake periods were more pronounced when the rhythms were desynchronized than when they were internally synchronized. This result provides evidence that the sex difference in periodicity is a property only of the sleep-wake rhythm; the intrinsic periods of temperature rhythms are identical in females and males, whereas those of sleep-wake rhythms are distinctly shorter in females than in males. In the state of internal synchronization, the joint period is a compromise between the intrinsic periods of the rhythms involved, and therefore it shows a small but significant sex difference. Moreover, the transition from internally synchronized to desynchronized rhythms is combined with a highly significant reduction in the sleep fraction, which is considerably greater in females than in males. These results suggest that the occurrence of internal desynchronization strongly affects the sleep-wake rhythm, and that the influence of rhythm disorders is considerably greater in females than in males.     

Age-related differences in the effect of in vivo administration of indomethacin on hemopoietic cell lineages of the spleen and bone marrow of mice.

During 21 days of indomethacin treatment, erythroid cells in the spleens of both young adult and older mice, and in the bone marrow of young adult mice, were increased significantly early in treatment, relative to age-matched control organs, and remained high throughout treatment. During drug exposure, the numbers of myeloid cells in young adult bone marrow, but not spleen, were reduced, but in older mice these cells were elevated in both organs. Lymphoid cells in the young adult and older mouse spleens decreased and increased, respectively, during treatment, but were unchanged and decreased, respectively, in the bone marrow of young adult and older mice. Monocyte-macrophage cells in the spleen were elevated but unchanged in the bone marrow of both age groups. During 14 days of indomethacin treatment of young adult mice, the proportions of precursor cells in DNA synthesis of only the splenic erythroid lineage were increased. Thus, the major hemopoietic lineages in both the bone marrow and spleen are affected by exposure to indomethacin in a time-dependent and age-dependent manner. For all lineages studied, those of the bone marrow were least disturbed and/or were first to recover, even during continued drug exposure.     

高校产学研一体化发展的实践与前瞻

本文探讨我国高校产学研一体化发展的必要性、可行性及其前景。从人类社会发展的历史特点入手，并借鉴了美国硅谷发展的经验和我国改革开放推进社会主义市场发展的需求，对高校产学研一体化发展的道路作了论述。针对目前高校产学研一体化中存在的问题，作者提出了加速高校产学研一体化发展的四条建议：1，高校产学研一体化发展必须转变观念，积极参与社会大循环；2，推进高校产学研一体化要有过硬的产品和准确的市场定位；3，高校产学研一体化发展要依托高科技园区，切实解决经费投入问题；4，高校产学研一体化发展要突出以人为本的思想，努力造就发明家和企业家。     

Effects of Freund's complete adjuvant on the dirunal rhythms of neuroendocrine processes and ornithine decarboxylase activity in various tissues of male rats

The aim of this study was to investigate the effects of Freund's complete adjuvant (FCA) on the diurnal rhythms of hormonal parameters in serum and ornithine decarboxylase (ODC) activity in various tissues of male rats. On days 1–2 after FCA, increase of ODC activity (used to evaluate the level of activation) was observed in the hypothalamus, pituitary gland, adrenal medulla, adrenal cortex, liver and lymphoid tissues, while the ODC activity in the kidney was reduced. This was accompanied by an increase in serum corticosterone. On days 3–4 after FCA, ODC activity remained elevated in the pituitary gland, liver and lymphoid tissues, while the ODC activity in the testes and panceas was reduced; kidney ODC activity returned to baseline. This was associated with increased serum levels of prolactin (Prl) and luteinizing hormone, but decreased growth hormone, testosterone and insulin. The increase in ODC activity in the thymus, as well as the reduced ODC activity in the testes and kidney, can be obtained with paraffin. Furthermore, bromocryptine microcapsules (CBLA) reduced the FCA-induced increase of ODC activity in the pituitary gland, liver and lymphoid tissues (days 3–4) but did not affect the changes in other tissues. The increase in ODC activity in the pituitary gland, liver and lymphoid tissues is specific for FCA. A role for Prl in the induction of ODC in liver and lymphoid tissues is suggested by the fact that CBLA suppresses this enhancement.     

Glycosylation defects in inherited muscle disease

The gene mutated in the myodystrophy mouse, a model of muscular dystrophy, encodes a putative glycosyltransferase, Large. Mutations in genes encoding proteins thought to be involved in glycosylation have now been identified in six human forms of muscular dystrophy. Hereditary inclusion body myopathy and Nonaka myopathy result from defects in sialic acid production. Two forms of congenital muscular dystrophy, Fukuyama-type and MDC1C, result from mutations in members of the fukutin family. MDC1C and limb girdle muscular dystrophy type 2I are allelic, as they are both associated with mutations in the FKRP gene. Mutations in POMGnT, which encodes an enzyme involved in the synthesis of O-mannosyl glycans, result in muscle-eye-brain disease--another congenital form of muscular dystrophy. Abnormal alpha-dystroglycan has been reported in the myodystrophy mouse, and in the congenital and limb girdle muscular dystrophies. Recent data have shown that there is altered glycosylation of the protein and that this reduces its ability to bind to extracellular matrix ligands such as laminin and agrin.     

Maternal eating behavior is a major synchronizer of fetal and postnatal peripheral clocks in mice

Most living organisms show circadian rhythms in physiology and behavior. These oscillations are generated by endogenous circadian clocks, present in virtually all cells where they control key biological processes. To study peripheral clocks in vivo, we developed an original model, the Rev-Luc mouse to follow noninvasively and longitudinally Rev-Luc oscillations in peripheral clocks using in vivo bioluminescence imaging. We found in vitro and in vivo a robust diurnal rhythm of Rev-Luc, mainly in liver, intestine, kidney and adipose tissues. We further confirmed in vivo that Rev-Luc peripheral tissues are food-entrainable oscillators, not affected by age or sex. These data strongly support the relevance of the Rev-Luc model for circadian studies, especially to investigate in vivo the establishment and the entrainment of the rhythm throughout ontogenesis. We then showed that Rev-Luc expression develops dynamically and gradually, both in amplitude and in phase, during fetal and postnatal development. We also demonstrate for the first time that the immature peripheral circadian system of offspring in utero is mainly entrained by maternal cues from feeding regimen. The prenatal entrainment will also differentially determine the Rev-Luc expression in pups before weaning underlining the importance of the maternal chrononutrition on the circadian system entrainment of the offspring.     

氮同位素示踪技术在研究地下水硝酸盐污染中的应用

氮是重要的生源要素之一,地下水中硝酸盐污染问题不容忽视;由于不同氮污染源的同位素组成不同,所以氮同位素示踪技术应用于地下水硝酸盐污染研究具有重要意义。本文重点介绍了氮同位素示踪的基本原理及其测定方法,并归纳总结了氮同位素示踪技术在地下水中硝酸盐污染研究中的应用现状,指出了今后研究工作中值得重视的有关问题。     

Schwann cell mitochondria as key regulators in the development and maintenance of peripheral nerve axons

Formation of myelin sheaths by Schwann cells (SCs) enables rapid and efficient transmission of action potentials in peripheral axons, and disruption of myelination results in disorders that involve decreased sensory and motor functions. Given that construction of SC myelin requires high levels of lipid and protein synthesis, mitochondria, which are pivotal in cellular metabolism, may be potential regulators of the formation and maintenance of SC myelin. Supporting this notion, abnormal mitochondria are found in SCs of neuropathic peripheral nerves in both human patients and the relevant animal models. However, evidence for the importance of SC mitochondria in myelination has been limited, until recently. Several studies have recently used genetic approaches that allow SC-specific ablation of mitochondrial metabolic activity in living animals to show the critical roles of SC mitochondria in the development and maintenance of peripheral nerve axons. Here, we review current knowledge about the involvement of SC mitochondria in the formation and dysfunction of myelinated axons in the peripheral nervous system.     

Cell proliferation, carcinogenesis and diverse mechanisms of telomerase regulation

Replication of linear genomes is incomplete and leaves terminal gaps. Solutions to this 'end replication' problem can be traced back to the prebiotic RNA world: 'fossils' of the presumptive archetypes of telomere structure and of the telomerase enzyme are retained in the terminal structures of some RNA viruses. Telomerase expression in mammals is ubiquitous in embryonic tissues but downregulated in somatic tissues of adults. Exceptions are regenerative tissues and, notably, tumor cells. Telomerase activation is controlled by cellular proliferation, and it is an early step in the development of many tumors. In contrast to mammals, indeterminately growing multicellular organisms, such as fish and crustaceae, maintain telomerase competence in all somatic tissues. In human tumor diagnostics, detection of proliferation markers with monoclonal antibodies is well established, and in this review, the significance of additional telomerase assays is evaluated. Telomerase inhibitors are attractive goals for application in tumor therapy, and telomerase knockout mice have proven that telomere erosion limits the lifespan of cells in vivo. In contrast, telomerase stimulation can be used to expand the potential of cellular proliferation in vitro, with possible applications for transplantation of in vitro expanded human cells, for immortalizing primary human cells as improved tissue models and for the isolation of otherwise intractable products, such as genuine human monoclonal antibodies.     

Characterization of D-fructose transport by rat kidney brush-border membrane vesicles: changes in hypertensive rats

D-fructose transport was characterized in renal brush-border membrane vesicles (BBMVs) from both spontaneously hypertensive rats (SHR) and normotensive genetic control Wistar-Kyoto (WKY) rats. Kinetic studies indicated that the maximal rate (Vmax) of D-fructose transport was significantly lower in SHR compared with WKY rats. No differences were observed in the Michaelis constant (Km) or the diffusion constant (Kd) between the two groups of animals. D-fructose inhibited its own transport, whereas the presence of D-glucose, D-galactose, phlorizin, and cytochalasin B did not inhibit the transport of D-fructose in either animal group. To explain the reduction in D-fructose transport in SHR, the density of the D-fructose transporter, GLUT5, was analyzed by Western blot. GLUT5 levels were lower in SHR, a reduction similar to that of the Vmax. Thus, there appears to be a high-affinity, low-capacity, GLUT5-type fructose carrier in the apical membranes of rat kidney cortex, and the decrease in the Vmax of D-fructose transport in renal BBMVs from hypertensive rats correlates well with a reduction in the expression of GLUT5 protein.     

The genetic code in mitochondria and chloroplasts

The universal genetic code is used without changes in chloroplasts and in mitochondria of green plants. Non-plant mitochondria use codes that include changes from the universal code. Chloroplasts use 31 anticodons in translating the code; a number smaller than that used by bacteria, because chloroplasts have eliminated 10 CNN anticodons that are found in bacteria. Green plant mitochondria (mt) obtain some tRNAs from the cytosol, and genes for some other tRNAs have been acquired from chloroplast DNA. The code in non-plant mt differs from the universal code in the following usages found in various organisms: UGA for Trp, AUA for Met, AGR for Ser and stop, AAA for Asn, CUN for Thr, and possibly UAA for Tyr. CGN codons are not used by Torulopsis yeast mt. Non-plant mt, e.g. in vertebrates, may use a minimum of 22 anticodons for complete translation of mRNA sequences. The following possible causes are regarded as contributing to changes in the non-plant mt: directional mutation pressure, genomic economization, changes in charging specificity of tRNAs, loss of release factor RF2, changes in RF1, changes in anticodons, loss of lysidine-forming enzyme system, and disappearance of codons from coding sequences.     

Developmental and ageing changes in aminopeptidase activities in selected tissues of the rat

Aminopeptidase activities, assayed as arylamidase activities, were investigated in selected tissues of 1, 6, 12 and 24-month-old rats. The enzyme activities were found to have a heterogeneous distribution and age-related changes were observed. The highest levels of soluble arginyl-aminopeptidase activity were detected in brain homogenate at all the studied ages, whereas membrane-bound activity presented the highest levels in brain and kidney in the four ages tested. Aspartyl-aminopeptidase activity was detected mainly in the particulate fraction of kidney at all four ages. In 1, 6 and 12-month-old animals, soluble aspartyl-aminopeptidase activity was also higher in the kidney than in the rest of the tissues, whereas in the group of 2-year-old rats, the highest levels were found in both kidney and liver. Age-related changes were observed in all the studied tissues and for all the assayed enzymatic activities. In general, the maximal levels were detected in both the youngest and the oldest animals, and the minimal ones in 6 and 12-month-old rats. However, in the adrenals, the soluble and membrane-bound arginyl-aminopeptidase activity was higher in 6-month and 2-year-old rats than in 1-month and 12-month-old rats. These changes may reflect the functional status of the susceptible endogenous substrates of aminopeptidases.     

Zinc,copper and selenium in reproduction

Of the nine biological trace elements, zinc, copper and selenium are important in reproduction in males and females. Zinc content is high in the adult testis, and the prostate has a higher concentration of zinc than any other organ of the body. Zinc deficiency first impairs angiotensin converting enzyme (ACE) activity, and this in turn leads to depletion of testosterone and inhibition of spermatogenesis. Defects in spermatozoa are frequently observed in the zinc-deficient rat. Zinc is thought to help to extend the functional life span of the ejaculated spermatozoa. Zinc deficiency in the female can lead to such problems as impaired synthesis/secretion-of (FSH) and (LH), abnormal ovarian development, disruption of the estrous cycle, frequent abortion, a prolonged gestation period, teratogenicity, still-births, difficulty in parturition, pre-eclampsia, toxemia and low birth weights of infants. The level of testosterone in the male has been suggested to play a role in the severity of copper deficiency. Copper-deficient female rats are protected against mortality due to copper deficiency, and the protection has been suggested to be provided by estrogens, since estrogens alter the subcellular distribution of copper in the liver and increase plasma copper levels by inducing ceruloplasmin synthesis. The selenium content of male gonads increases during pubertal maturation. Selenium is localized in the mitochondrial capsule protein (MCP) of the midpiece. Maximal incorporation in MCP occurs at steps 7 and 12 of spermatogenesis and uptake dereases by step 15. Selenium deficiency in females results in infertility, abortions and retention of the placenta. The newborns from a selenium-deficient mother suffer from muscular weakness, but the concentration of selenium during pregnancy does not have any effect on the weight of the baby or length of pregnancy. The selenium requirements of a pregnant and lactating mother are increased as a result of selenium transport to the fetus via the placenta and to the infant via breast milk.     

Scientific Instruments for Education in Early Twentieth-Century Spain

1898 marked a crucial point in the end of the nineteenth-century Spanish crisis. The military defeat ending the Spanish-American War was seen as proof that the country was in terminal decline. With the ideals of regeneration spreading throughout Spanish society, the State became more interested in supporting and sponsoring science and technology, as well as in creating a modern educational system. The resulting reforms reflected this strong interest in scientific education, and consequently, the first decades of the twentieth century saw a turning point in the development of science and technology in Spain. Some recent papers have discussed various initiatives taken by Spanish governments, particularly in the creation of new official institutions. Such institutions played an important role in the development of science and technology, but their activity in the promotion of scientific education was very limited. However, other governmental initiatives were taken in order to develop this area, particularly focusing on the acquisition of scientific instruments. Scientific instruments were needed not only to improve Spanish scientific research but also to improve the teaching of experimental sciences. These instruments were specifically adapted for use by students. This paper aims to present some of the lesser-known individuals and firms who, in the new social and cultural context, provided scientific instruments for educational centres in order to meet the increasing demand for this material in Spanish educational institutions during these years.