Crystallization and preliminary crystallographic data of the Fab fragment of an anti-phenylalanine hydroxylase monoclonal antibody

Two crystal habits, one rod shaped and the other square prismatic, of the Fab fragment of a monoclonal anti-phenylalanine hydroxylase antibody have been grown using the method of vapour phase diffusion against polyethylene glycol 6000. The square prisms diffract to better than 2.8 A, belong to the space group P1 and have unit cell parameters a = 41.8 A, b = 50.3 A, c = 114.7 A, alpha = 97.6 degrees, beta = 91.7 degrees, gamma = 91.0 degrees, while the rod-shaped crystals belong to the space group P212121, have unit cell parameters a = 105.6 A, b = 119.8 A, c = 82.2 A and diffract to 3.5 A resolution.     

MSI2通过下调circRNA_001214促进急性髓系白血病细胞HL60生长

Musashi-2（MSI2）是一种RNA结合蛋白质,对维持造血干细胞功能具有重要作用。研究表明,MSI2高表达能促进急性髓系白血病（acute myelocytic leukemia, AML）进展,但其作用机制尚不明确。本研究稳定沉默HL60细胞MSI2后,第1、2、3、4 d对照组的相对细胞生长率分别为1.931 ± 0.027、3.070 ± 0.073、4.017 ± 0.092和4.215 ± 0.246;敲减组分别为1.927 ± 0.035、2.564 ± 0.090、2.825 ± 0.097和3.223 ± 0.182,两组相比具有统计学差异,P<0.001;细胞凋亡明显增加(7.967% ± 0.698% vs 3.400% ± 0.322%., P<0.01);G₀/G₁期细胞比例明显增高（67.430% ± 4.390% vs. 50.360% ± 2.160%, P<0.01）;NUMB蛋白明显上调,LEF1明显下降。环状RNA（circular RNA, circRNA）芯片筛选和荧光定量PCR验证显示,MSI2沉默组circRNA_001214表达水平是对照组3.48倍。这一结果也在NALM6细胞得到证实。进一步用生物信息学分析,显示circRNA_001214最可能与miR-1273a、miR-1273e和miR 5095结合,进而影响参与细胞凋亡相关基因（CYCS、AKT1、BAX、TNFRSF10A、TNFRSF10D）、Wnt信号基因（WNT4、WNT2B、WNT7B、 DKK2、SFRP1、CSNKE1和LEF1）以及参与细胞代谢相关基因（RPE, PGAM4, PGAM1, TAT, CBS、RPE、SUCLG2、PGAM4、PGAM1和 IDNK）。总而言之,MSI2可能通过干扰circRNA_001214生成,减少靶miRNA对凋亡、Wnt信号及细胞代谢相关基因表达的影响,促进细胞生长。     

Secretory bursts of growth hormone secretion in the dog may be initiated by somatostatin withdrawal

In 28 6-h experiments on 10 conscious resting trained male dogs, plasma growth hormone (GH) was determined at 5-min intervals by radioimmunoassay. For all experiments, the basal GH concentration in plasma was 0.80 +/- 0.06 ng mL-1. In each experiment, 1-3 secretory bursts of GH occurred, raising plasma GH 2.4 to 15.3 times basal concentrations (for all 43 bursts, 6.6 +/- 0.4 times the basal value). Metabolic clearance rates (MCR) and apparent distribution volumes (V) were determined, using stepwise infusions of canine GH. The MCR (3.99 +/- 0.30 mL kg-1 min-1) and V (57.9 +/- 5.5 mL kg-1) were used to transform the GH concentration versus time data into GH secretion rates, using a single compartment approach. Basal GH secretion rates for all 28 experiments were 3.12 +/- 0.24 ng kg-1 min-1. The secretory bursts yield peak GH secretion rates of 9.4 +/- 0.8 times basal secretion and these steep-sloped bursts last 25.1 +/- 1.2 min. Six-hour infusions of 0.15 microgram kg-1 min-1 of somatostatin (SRIF) abolished all secretory bursts but did not lower basal secretion rates. In five of seven SRIF infusion experiments in which samples were taken after the infusion ceased a secretory burst was seen in the hour following cessation of infusion (in four cases within 10 min). These secretory bursts lasted 23.0 +/- 2.9 min and were similar to those seen in control experiments. Infusions of SRIF at 0.05 microgram kg-1 min-1 had no effect. These results imply that during basal GH secretion, a surfeit of SRIF impinges on the somatotrophs, as extra SRIF does not further lower basal secretion. However, during secretory bursts, very little SRIF must be present, as exogenous SRIF blocks these bursts. The bursts are similar in duration to overshoots provoked in perifused dispersed rat somatotrophs by removal of an SRIF signal. It seems likely that their cause in vivo is similar. (All values are means +/- SEM.)     

酪氨酸对大鼠离体Leydig细胞睾酮和cAMP生成的影响

本实验采用胶原酶消化,Ficoll 密度梯度离心,制备大鼠睾丸 Leydig 细胞悬浮液进行体外培养(每管内含有10~6 细胞),以研究酪氨酸对 Leydig 细胞睾酮和cAMP 生成的影响。实验结果表明,hCG(100mIU)能明显地促进Leydig 细胞睾酮和 cAMP的生成。睾酮从对照组的3.08±0.58ng(X±SD,下同)增加到41.61±1.52ng,cAMP 含量从19.62±2.56pmol增加到153.24±5.92pmol。若将酪氨酸(60μg)与hCG同时加入到细胞培养液中,则睾酮和cAMP 含量分别下降到 19.22±.0.52ng(P<0.01)和92.63±6.02pmol(P<0.05)。但是,酪氨酸羟化酶抑制剂(α-甲基酪氨酸)对酪氨酸抗hCG致睾酮生成作用无阻断效应,而酪氨酸对外源cAMP(2.5mM)诱导的睾酮生成,则有明显的抑制作用,睾酮含量从27.56±1.53ng降至 19.50±0.47ng(P<0.01)。以上实验结果表明,酪氨酸抗hCG致睾酮生成的作用机理与cAMP有关。     

云南叶螨属一新种(蜱螨目:叶螨科)

在鉴定云南叶螨标本时,发现叶螨属一新种,现记述如下。模式标本保存于上海农学院。本文量度单位均为微米。 食禾叶螨Tetranychus graminivorus新种(图1—14) 雌螨 体长(包括喙)454,宽298。椭圆形。浅黄绿色。须肢端感器圆柱形,长6.8,     

Feedback suppression of ACTH secretion by cortisol in dogs: lags after large signals equal those following very small signals

Previously, low stepwise infusions of cortisol in resting adrenalectomized dogs (plateaux less than or equal to 6 micrograms/dL) were shown to reduce ACTH secretion only after 20 min. In the present study, large, steep-sloped cortisol signals were used to try to evoke faster feedback. Adrenalectomized male mongrel dogs were maintained on exogenous steroids until 48 h before the experiment. Of the 23 experiments on 15 dogs (under light pentobarbital anesthesia), 12 were on resting dogs, 7 on dogs stressed by variable insulin infusion (keeping plasma glucose at 18-40 mg/dL), and 4 stressed as above but with 4 h of low cortisol infusion (plasma congruent to 5 micrograms/dL) before applying the feedback signal. After a 50-min control period, a 30-min feedback period was initiated by one of two i.v. cortisol signals: (a) injection of 0.3 mg/kg or (b) infusion of 46 micrograms kg-1 min-1. Both raised plasma cortisol above physiological limits (within 2 and 6 min, respectively). In each experiment, 23 timed venous blood samples were assayed for plasma ACTH and cortisol. ACTH secretion rates were calculated continuously using a validated single-compartment method. Results from both types of cortisol signals were indistinguishable, and were thus pooled. In the unstressed dogs, control-period ACTH secretion of 0.97 +/- 0.12 mU kg-1 min-1 showed no significant decline due to the feedback signal for 20.3 +/- 1.4 min.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of pinealectomy on seasonal changes in antler growth and concentrations of testosterone and prolactin in white-tailed deer

A 2-year study was conducted to determine under controlled conditions the role of the pineal gland in regulating the seasonal changes in antler growth and reproduction of male white-tailed deer. Blood samples were drawn from 6 pinealectomized (PX) and 18 control (C) deer at intervals of 2 weeks and analyzed for testosterone (T) and prolactin (Prl). Relative scrotal circumference and main beam antler length were recorded. Relative scrotal circumference was similar in PX and C groups, but the normal pattern was delayed 1 to 3 months in the PX deer relative to the C deer. The mean dates of beginning antler growth, velvet shedding, antler casting and pelage changes were significantly later in both years for PX deer than in C deer. Testosterone concentrations peaked 1 month later in the PX deer than in the C deer for both yearling and 2-year-old deer. Prl concentrations in C deer, but not in PX deer, were correlated highly with day length, and the PX deer were delayed relative to the C deer in showing the normal Prl pattern. Increasing levels of Prl in both groups coincided with beginning antler growth in both years. These results indicate that the pineal gland does not originate the seasonal cycles of male white-tailed deer but may synchronize cycles among individual deer, and regulate the circannual rhythm of Prl concentrations which may in turn influence other hormonal cycles.     

The relative role of stomata in transpiration and assimilation

Summary The ways in which transpiration and assimilation depend on stomatal aperture are compared. It is shown that transpiration and assimilation are equally sensitive to change of stomatal aperture when the internal resistance to assimilation is equal to an effective resistance to evaporation which exists because of the coupling of heat and vapour exchanges between leaf and atmosphere. Generally the ratio of transpiration to assimilation changes with stomatal aperture in a manner which is determined by the relative magnitude of these resistances and on temperature. Some possible implications in relation to the optimal behaviour of stomata are discussed.Work done while J.H.T. held a New Zealand D.S.I.R. Fellowship.     

中国东北地区常见有瓣蝇类调查初步报告

与人类杂处的蝇类,在我国东北地区的分布情况尚少系统调查。作者于1956年5月、8月曾赴内蒙东北部(伊图里河、图里河),6月、7月赴营口、盘山(田庄台),借这些机会,顺便采集了蝇类标本;同年9月组内同志去绥中也采回部分标本;1957年5月至10月作者又赴吉林、辽宁两省各地进行了蝇类调查。其中有瓣蝇类已经定名的共计5科26属68种,有6种为国内新记录。兹将结果报告如下: