Calcitonin gene-related peptide (CGRP) in normotensive and spontaneously hypertensive rats

With the techniques of specific radioimmunoassay and gel filtration it was found that CGRP was distributed in various tissues of normotensive (WKY) and spontaneously hypertensive rats (SHR) with the highest concentration in the lumbar spinal cord (1197 +/- 94.8 pg/mg tissue) and the lowest in the auricle (15.0 +/- 2.1 pg/mg tissue). In comparison with WKY, CGRP concentration in the plasma was decreased and in the abdominal aorta and hypothalamus was increased in SHR. Gel filtration revealed only one major CGRP molecular form in the tissues. In addition, CGRP reduced the mean arterial pressure (MAP) in SHR in a dose-dependent manner. These data suggest that CGRP may play an important role in the pathogenesis of hypertension and its possible therapy.     

鼎突多刺蚁群体结构和生活史的研究

本文报告了鼎突多刺蚁(Polyrhachis vicina Roger)的群体结构和生活史。通过研究表明,鼎突多刺蚁一年发生一代,以蚁后、雄蚁、工蚁、幼虫和卵越冬。卵和幼虫在冬天发育停滞(或极慢)。到了春天,随着气温的上升,卵和幼虫又恢复正常发育。据室内人工饲养观察,卵的发育历期为23.8±2.5天(平均温度26℃)幼虫为20.4±4.4天(26℃),工蚁蛹为19.8±5.5天(27℃)。成长工蚁在5—11月出现;8—11月,雄蚁从蛹中羽化;10月,雌蚁从蛹中羽化。雌蚁分飞交尾后,进入邻近蚁巢或回到原巢,脱翅成为蚁后。蚁巢内存在着多后现象。     

贵州两栖动物区系及地理区划的初步研究

本文报道贵州省两栖动物63种,其中省新纪录2种,即阔褶蛙和锯腿树蛙。将贵州划分为黔西高原中山、黔北中山峡谷、黔中山原丘陵、黔东南低山丘陵盆地和黔南低山河谷五个动物地理省。认为黔南低山河谷省属于向华南区过渡的华中地带。讨论了各动物地理省的地貌、气候、两栖动物区系特征及地理替代种类。分析了各动物地理省两栖动物区系的相似性及数量关系。     

Competition in the gradostat: the role of the communication rate

In this paper we study a mathematical model of competition between two species of microorganisms for a single limiting nutrient in a laboratory device called a gradostat. A gradostat consists of several (we consider only two) chemostats (CSTR's) connected together so that material can flow between the vessels in such a way that a nutrient gradient is established. Our model is a slightly modified version of one considered recently by Jäger et al. [3], in that the rate of exchange of material between the two vessels (the communication rate) is allowed to differ from the dilution rate. The outcome of competition turns out to be surprisingly sensitive to variation of the communication rate. We identify several coexistence regimes in parameter space and describe a method for obtaining operating diagrams for given pairs of competing microorganisms.Research supported in part by NSF Grant DMS 8521605     

Base and conformational specificity of an amine modification of DNA

We have investigated the site and conformational preference of the reaction of a formaldehyde/amine reagent with DNA. Previous investigations of this laboratory have established that this reagent will react with native DNA, placing a positively charged amine moiety on the duplex that will survive exhaustive dialysis. The resulting adduct is duplex and base stacked in character, possessing B backbone geometry with a higher average winding angle and exhibiting remarkable stability with respect to the A-form, Z-form, or the single-strand denaturated species. In this current investigation, we have found that the stability of the adduct is dramatically reduced if the DNA is converted to mononucleotides, thus obviating the usual approach of nuclease digestion and chromatography for the identification of the modified nucleotides. Using indirect approaches, we have established that the reactive site that survives removal of the equilibrium concentrations of CH2O and amine is the exocyclic amino group of the guanine bases. This conclusion is based on (1) the positive correlation between GC content and the extent of adduct formation under standard reaction conditions (27 degrees C, 0.63M CH2O, 0.007M n-butylamine, pH 7); (2) decreases in the level of substitution of amine in DNA, which has this site blocked by trinitrobenzene modification; and (3) failure of poly(dI-dC) to retain amine upon dialysis. Raman spectra of the derivatized poly(dG-dC) show enhanced 2'-endo B character, with no marked shifts in the position of any of the lines, indicating the absence of any ring structures involving the N7 and the 06 of G. In standard reaction mixtures, other sites may react but this phenomenon appears to be minimal under conditions that do not favor fluctuational opening of base pairs. In the latter case, excess loading of amine on high GC content polymers produces a CD spectrum that is similar to one produced by poly(dA-dT) in the "X"-form [M. Vorlickova, E. Minyat, and J. Kypr (1984) Biopolymers 23, 1-4]. This conformation is lost, however, upon removal of excess reagents by dialysis and cannot be reestablished, in the absence of unbound amine and formaldehyde. The reaction is specific for the B-form of polynucleotides as demonstrated by the failure of poly(dG-m5dC) in the stable Z-form to exhibit substantial reaction. The B-form of this polymer will react readily with the retention of 0.23 moles amine/mole nucleotide under our standard reaction conditions.(ABSTRACT TRUNCATED AT 400 WORDS)     

Ca2+ channels in chick neural retina cells characterized by 1,4-dihydropyridine antagonists and activators

The voltage-sensitive calcium channel in cultured chick neural retina cells was characterized by the actions of the enantiomers of Bay K 8644 and 202-791 and other 1,4-dihydropyridines. These cells showed time- and voltage-dependent Ca2+ uptake that was stimulated by K+ depolarization and blocked by the inorganic calcium channel blockers Cd2+ and Co2+. A small fraction only (15% maximum) of the uptake was inactivated by predepolarization of the cells with 80 mM K+. Ca2+ uptake was sensitive to the 1,4-dihydropyridine calcium channel antagonists and activators. (S)-Bay K 8644 and (S)-202-791 stimulated the Ca2+ uptake, and (R)-Bay K 8644 and (R)-202-791 as well as nitrendipine and PN 200-110 inhibited Ca2+ uptake stimulated by K+ depolarization or channel activators. The K+ depolarization-stimulated uptake was inhibited by 90%, but the activator-stimulated uptake was completely blocked by the 1,4-dihydropyridine antagonists. The potencies of these agents as inhibitors of Ca2+ uptake were significantly lower than the binding affinities in membrane preparations from the same cells or their binding and pharmacologic affinities in vascular smooth muscle. K+ depolarization or (S)-Bay K 8644 induced 45Ca2+ uptake was not observed in a glial cell culture. [3H]Nitrendipine and [3H]PN 200-110 bound to membrane preparations of the cells consistent with the presence of a single type of high affinity binding site.(ABSTRACT TRUNCATED AT 250 WORDS)     

Polyclonal antibodies to rabbit skeletal muscle protein phosphatases C-I and C-II

Polyclonal antibodies against rabbit skeletal muscle phosphatases C-I and C-II were raised in goats and in mice. The goat polyclonal antibodies to phosphatases C-I and C-II were examined for their ability to immunoblot the purified enzymes and crude rabbit muscle extracts. In preparations of phosphatases C-I and C-II that were apparently homogeneous, the expected ca. 35- to 38-kDa polypeptides were immunoblotted, but, in addition, immunoblotting of a 67-kDa polypeptide was observed. Both the antisera blotted only the 67-kDa polypeptide in crude rabbit muscle extracts and not the expected 35- to 38-kDa polypeptides. These findings are qualitatively similar to those reported previously (D.L. Brautigan et al. (1985) J. Biol. Chem. 260, 4295-4305) where immunoblotting experiments with a sheep antisera to phosphatase C-I indicated that the ca. 35-kDa polypeptide originates from a 70-kDa precursor. On further investigation, it was found that our antisera were strongly immunoreactive to rabbit serum albumin. The antisera blotted purified rabbit albumin, but not bovine serum albumin. After passage through a rabbit albumin-Sepharose column, the antisera lost immunoreactivity to rabbit albumin, and no longer blotted the ca. 70-kDa band in muscle extracts or in purified enzyme preparations. These findings show that the phosphatase preparations contained traces of albumin which produced a strong antigenic reaction. Production of antisera in BALB/c mice produced similar results; i.e., an antibody to the low-molecular-weight phosphatases was produced that was also a strong antibody to rabbit albumin. This antibody could be removed by affinity adsoption on rabbit albumin-Sepharose columns. In addition, the antibodies to phosphatase C-I displayed no cross-reactivity to phosphatase C-II, while antibodies to C-II showed no cross-reactivity to phosphatase C-I by immunoblotting methods.     

Liver mitochondrial respiratory functions decline with age

Human liver mitochondrial respiration rates in Chinese populations of various ages were assayed with an oxygraph. In this study, State 3 and State 4 respiration rates, respiratory control ratio (RCR), and ADP/O ratio were measured for 35 Chinese subjects of 31 to 76 years old. We found a significant negative correlation between age and respiratory control and ADP/O ratios tested. Moreover, the respiratory control and ADP/O ratios decreased with the increase of age. These findings suggest that a substantial fall in mitochondrial oxidative capacity in ageing liver may be an important contributor to the ageing process.     

Cytostatic effect of antiestrogens in lymphoid cells: relationship to high affinity antiestrogen-binding sites and cholesterol

The antiproliferative effect of 10(-6) M antiestrogens in an estrogen receptor-negative lymphoid cell line (K36) was enhanced in lipoprotein-poor growth medium. The enhancement was not due to increased bioavailability because cellular uptake of [3H]tamoxifen was not increased and the lipoprotein fraction of serum had negligible [3H]tamoxifen-binding capacity. Cholesterol and lipoproteins, but not mevalonate, reversed the cytostatic effect of antiestrogens. Reversal by cholesterol was dose-related (10(-7) M to 10(-5) M), while that by lipoproteins could also be demonstrated in medium undepleted of lipoproteins. The cytostatic efficacy of a series of ten compounds correlated well with their relative binding affinities for solubilized antiestrogen-binding sites from K36 cells when log IC50 values (concentration required to reduce [3H]thymidine incorporation by 50%) were plotted against log RBA50 values (concentration required to reduce [3H]tamoxifen binding by 50%) (correlation coefficient 0.94). Transmission electron microscopy of antiestrogen-treated cells showed evidence of disordered cytokinesis which was partially reversed by cholesterol. These observations implicate the antiestrogen-binding protein in the antiproliferative effect of antiestrogens in nonestrogen target cells.