凝集素碎片的糖结合活性

用固相合成法分别合成了羊蹄甲、小扁豆和欧洲百脉根３种植物凝集素中的某些糖结合活性部位的肽段。用毛细管电泳法观察到这些肽段和拟糖蛋白以及寡糖之间有一定的结合能力,而且表现出相对的专一性。     

Effect of Structural Changes of Pro6 in Dermorphin Molecule on Its Antinociceptive Activity

We studied effect of dermorphin (H-Tyr-DAla-Phe-Gly-Tyr-Pro-Ser-NH₂) and its analogs with modified amino acid residue proline in position 6, H-Tyr-DAla-Phe-Gly-Tyr-[DPro]-Ser-NH₂, H-Tyr-DAla-Phe-Gly-Tyr-[dehydro-Pro]-Ser-NH₂, and H-Tyr-DAla-Phe-Gly-Tyr-[D-dehydro-Pro]-Ser-NH₂, on nociception in the tail-flick and hot plate tests after intraperitoneal injection. Replacement of LPro with the stereoisomer DPro as well as Pro dehydration (LdHPro) was shown to increase antinociceptive activity. Replacement of LdHPro with DdHPro cancelled the activity in the tail-flick test. All three dermorphin analogs retained antinociceptive activity in the hot plate test; however, the effect of dermorphin was more pronounced.     

Synthesis of Human Growth Hormone Fragments with Growth-promoting Activity

WE have reported¹ the synthesis and growth-promoting activity of two polypeptides corresponding to the sequences 81–121 and 122–153 of the human growth hormone (HGH) proposed by Li². Studies of the HGH internal homologies and the comparison between HGH and ovine prolactin³ (OP) sequences have helped us in the recognition of somatotrophic active sites. After the primary structure revision^4,5, internal homologies of HGH and external homologies between HGH and OP emerge even more clearly.     

Dermorphin: synthesis of analogs and structuro-functional relations

The review analyzes structure-activity relations among dermorphin analogues. Dermorphin (Tyr-D-Ala-Phe-Gly-Tyr-Pro-Ser-NH2) is one of natural opioid peptides having a unique structure and exerting a very potent and prolonged antinociceptive effect. Methods of dermorphin synthesis are summarized together with data on more than 300 dermorphin-like peptides: the physico-chemical characteristics and data on opioid tests in vitro and in vivo are discussed. Based on these studies, conclusions have been drawn on the functional role of each amino acid residue in the dermorphin molecule and on modifications leading to analogues with high and differential opioid activity.     

Effects of Calcium on Template Activity and Size of Pea Chromatin Fragments

Pea chromatin was fractionated into template active and inactivefragments by cleavage with DNase II followed by fractionationwith Bio-Gel A 5 m column chromatography. When the chromatin fragments were chromatographed in the presenceof Ca²⁺ or EGTA, the elution patterns suggested that Ca²⁺ assembledmoderately digested chromatin fractions. Moreover, total templateactivity of chromatin fractions was reduced by Ca²⁺ and theactive fraction was eluted at different positions under thechelated and non-chelated conditions. (Received February 12, 1986; Accepted May 28, 1986)     

Activity of Deoxyribonucleic Acid Fragments of Defined Size in Bacillus subtilis Transformation

The transforming activity of Bacillus subtilis deoxyribonucleic acid (DNA) that had been sheared and purified with respect to size by sucrose gradient sedimentation is given as a function of the DNA molecular weight. It is shown (i) that fragments of median molecular weight 1.2 x 10(6) have finite activity (10(-4)), (ii) that the shape of the activity-versus-molecular weight function is qualitatively similar to that observed previously for Diplococcus pneumoniae, and (iii) that this shape precludes interpretation in terms of critical size models.     

Thermoregulatory mechanisms in Sarcophaga

Summary The flesh fly, Sarcophaga, is frequently seen feeding on flowers during periods of high radiation when other flies of comparable size avoid exposure because of the dangers of overheating. Sarcophaga is able to maintain its intermittent flower visits due to a cuticle of high thermal reflectance, giving low intrinsic heating rates, and to an ability to shunt blood between thorax and abdomen according to its needs. The fly thus achieves partial thermoregulation and can keep its body temperature within the preferred range for longer periods than its potential entomophilous competitors.     

Thermoregulatory shivering during exercise

Three subjects with lowered internal body temperatures performed brief bouts of bicycle ergometer exercise at 150 and 200 W. Oxygen uptake during exercise was consistently greater than that required by the working muscles, the increase being the result of the additional cost of shivering. Increases in metabolism during exercise above control levels were inversely proportional to internal temperature (with skin temperature constant) below a given internal temperature threshold. Observations of intense shivering during exercise which is proportional to lowered internal temperature in the same manner as during rest provides further evidence against the concept of a decrease in the thermoregulatory set point during exercise in man.     

Conformational Aspects of Biological Activity of Functional Fragments of the p21ras Oncoproteins: 4. Address Fragments of the Receptor Oncoproteins

Decapeptide fragments of the src, fgr, fps, and yes oncoproteins were studied by theoretical conformational analysis, and the arrangement of ionized residues in these fragments was found to be complementary to the binding site of p21. The results demonstrated a similarity in conformational properties of these peptides and their structural complementarity to the address fragment of p21. On the basis of this computation, a model of interaction of the p21ras family of oncoproteins with their cellular receptors was suggested.     

Thermoregulatory responses of diabetic rats

1. Thermal responses and skin microcirculation were measured in streptozotocin-induced diabetic (SD) rats during acute and chronic exposure to ambient (Ta) temperatures ranging from about 5 to 35 degrees C. 2. At 28 degrees C, SD rats had higher rate of oxygen consumptions (VO2), tail skin blood flow (SKBF), but lower rectal temperatures (Tre) than saline-injected controls. 3. Chronic exposure of the SD rats to 35 and 5 degrees C caused a sharp rise and decline in Tre, respectively. 4. At 35 degrees C, hyperthermia in the SD rats was associated with greater increase in VO2 than controls, but changes in SKBF were similar in both groups. 5. At 5 degrees C, VO2 changed similarly in both the SD and control rats, but vasoconstriction was greater in the controls. 6. The data suggest that hypothermia in SD rats may be associated with impairment of vasoconstriction and hyperthermia may be related to an increase VO2 not accompanied by greater vasodilation.     

Enhanced Slow-Wave EEG Activity and Thermoregulatory Impairment following the Inhibition of the Lateral Hypothalamus in the Rat

Neurons within the lateral hypothalamus (LH) are thought to be able to evoke behavioural responses that are coordinated with an adequate level of autonomic activity. Recently, the acute pharmacological inhibition of LH has been shown to depress wakefulness and promote NREM sleep, while suppressing REM sleep. These effects have been suggested to be the consequence of the inhibition of specific neuronal populations within the LH, i.e. the orexin and the MCH neurons, respectively. However, the interpretation of these results is limited by the lack of quantitative analysis of the electroencephalographic (EEG) activity that is critical for the assessment of NREM sleep quality and the presence of aborted NREM-to-REM sleep transitions. Furthermore, the lack of evaluation of the autonomic and thermoregulatory effects of the treatment does not exclude the possibility that the wake-sleep changes are merely the consequence of the autonomic, in particular thermoregulatory, changes that may follow the inhibition of LH neurons. In the present study, the EEG and autonomic/thermoregulatory effects of a prolonged LH inhibition provoked by the repeated local delivery of the GABA_A agonist muscimol were studied in rats kept at thermoneutral (24°C) and at a low (10°C) ambient temperature (Ta), a condition which is known to depress sleep occurrence. Here we show that: 1) at both Tas, LH inhibition promoted a peculiar and sustained bout of NREM sleep characterized by an enhancement of slow-wave activity with no NREM-to-REM sleep transitions; 2) LH inhibition caused a marked transitory decrease in brain temperature at Ta 10°C, but not at Ta 24°C, suggesting that sleep changes induced by LH inhibition at thermoneutrality are not caused by a thermoregulatory impairment. These changes are far different from those observed after the short-term selective inhibition of either orexin or MCH neurons, suggesting that other LH neurons are involved in sleep-wake modulation.     

Biological Activity and Antidiabetic Potential of C-Terminal Octapeptide Fragments of the Gut-Derived Hormone Xenin

Xenin is a peptide that is co-secreted with the incretin hormone, glucose-dependent insulinotropic polypeptide (GIP), from intestinal K-cells in response to feeding. Studies demonstrate that xenin has appetite suppressive effects and modulates glucose-induced insulin secretion. The present study was undertaken to determine the bioactivity and antidiabetic properties of two C-terminal fragment xenin peptides, namely xenin 18–25 and xenin 18–25 Gln. In BRIN-BD11 cells, both xenin fragment peptides concentration-dependently stimulated insulin secretion, with similar efficacy as the parent peptide. Neither fragment peptide had any effect on acute feeding behaviour at elevated doses of 500 nmol/kg bw. When administered together with glucose to normal mice at 25 nmol/kg bw, the overall insulin secretory effect was significantly enhanced in both xenin 18–25 and xenin 18–25 Gln treated mice, with better moderation of blood glucose levels. Twice daily administration of xenin 18–25 or xenin 18–25 Gln for 21 days in high fat fed mice did not affect energy intake, body weight, circulating blood glucose or body fat stores. However, circulating plasma insulin concentrations had a tendency to be elevated, particularly in xenin 18–25 Gln mice. Both treatment regimens significantly improved insulin sensitivity by the end of the treatment period. In addition, sustained treatment with xenin 18–25 Gln significantly reduced the overall glycaemic excursion and augmented the insulinotropic response to an exogenous glucose challenge on day 21. In harmony with this, GIP-mediated glucose-lowering and insulin-releasing effects were substantially improved by twice daily xenin 18–25 Gln treatment. Overall, these data provide evidence that C-terminal octapeptide fragments of xenin, such as xenin 18–25 Gln, have potential therapeutic utility for type 2 diabetes.     

侧孢短芽孢杆菌X10启动子活性片段的克隆和序列分析

提取了侧孢短芽孢杆菌X10的基因组DNA,以绿色荧光蛋白基因(green fluorescent protein,gfp)为报告基因,以启动子探针pUC19-GFP为载体,通过鸟枪法在大肠杆菌DH5α中构建了X10的启动子文库,通过筛选获得了14个阳性克隆,编号为P1～P14.测定了阳性克隆子的荧光强度,结果表明P6中gfp基因的启动子活性最强,它的荧光强度达到了355.67,而P14中gfp基因的启动子活性最弱,它的荧光强度只有211.67.对P6克隆中的重组质粒的插入片段进行了测序和序列分析.     

Thermoregulatory effects of purines and caffeine

Purines are putative neurotransmitters which appear to be involved in regulating several vegetative functions. We examined the effect of purines and their antagonist, caffeine, on colonic temperature of rats. Adenosine injected ip lowered colonic temperature in a dose responsive manner at ambient room temperatures. Adenine and AMP also lowered body temperature whereas 7-methylinosine and inosine only slightly influenced colonic temperature. Caffeine (50 mg/kg) injected sc, increased colonic temperature and when injected within 60 seconds of adenosine, counteracted the hypothermic effect of adenosine (50 mg/kg). Low ambient temperature (4°C) accentuated the thermoregulatory effects of adenosine. Thus adenosine appears to have a hypothermic effect on body temperature regulation when administered peripherally which can be reversed by caffeine.     

City-Scale Expansion of Human Thermoregulatory Costs

The physiological maintenance of a stable internal temperature by mammals and birds – the phenomenon termed homeothermy – is well known to be energetically expensive. The annual energy requirements of free-living mammals and birds are estimated to be 15–30 times higher than those of similar-size ectothermic vertebrates like lizards. Contemporary humans also use energy to accomplish thermoregulation. They are unique, however, in having shifted thermoregulatory control from the body to the occupied environment, with most people living in cities in dwellings that are temperature-regulated by furnaces and air conditioners powered by exogenous energy sources. The energetic implications of this strategy remain poorly defined. Here we comparatively quantify energy costs in cities, dwellings, and individual human bodies. Thermoregulation persists as a major driver of energy expenditure across these three scales, resulting in energy-versus-ambient-temperature relationships remarkably similar in shape. Incredibly, despite the many and diversified uses of network-delivered energy in modern societies, the energy requirements of six North American cities are as temperature-dependent as the energy requirements of isolated, individual homeotherms. However, the annual per-person energy cost of exogenously powered thermoregulation in cities and dwellings is 9–28 times higher than the cost of endogenous, metabolic thermoregulation of the human body. Shifting the locus of thermoregulatory control from the body to the dwelling achieves climate-independent thermal comfort. However, in an era of amplifying climate change driven by the carbon footprint of humanity, we must acknowledge the energetic extravagance of contemporary, city-scale thermoregulation, which prioritizes heat production over heat conservation.     

Effect of Dermorphin Analogs on Thermoregulation of Rats under Various Thermal Conditions

We studied the influence of dermorphin (dermorphin) analogs with stereochemical modification of the amino acid residue proline in position 6 (Pro6), Tyr-D-Ala-Phe-Gly-Tyr-Hyp-Ser-NH₂, Tyr-D-Ala-Phe-Gly-Tyr-[D-Pro]-Ser-NH₂, Tyr-D-Ala-Phe-Gly-Tyr-[dehydro-Pro]-Ser-NH₂, and Tyr-D-Ala-Phe-Gly-Tyr-[D-dehydro-Pro]-Ser-NH₂, after their intraperitoneal injection at 0.5 mg/kg dose in the cold (4–7°C), thermoneutral (27–28°C), and hot (31–33°C) environment. Stereochemical modifications of amino acid residue Pro6 proved to induce specific changes in the thermoregulatory effect of the peptide. Substitution of DPro6 for Pro6 has the most dramatic consequences: it considerably attenuates the thermoregulatory effect of dermorphin in the cold environment, cancels it in the hot environment, and inverts the dermorphin-specific thermoregulatory response in thermoneutral conditions. The data obtained indicate the important role of Pro6 residue in realization of this physiological activity of dermorphins.