The structure and evolution of the human salivary proline-rich protein gene family

We present the nucleotide sequences of four members of the six-member human salivary prolinerich protein (PRP) gene family. The four genes are PRB1 and PRB2, which encode basic PRPs, and PRB3 and PRB4, which encode glycosylated PRPs. Each PRB gene is approximately 4.0 kb in length and contains four exons, the third of which is entirely composed of 63-bp tandem repeats and encodes the proline-rich portion of the protein products. Exon 3 contains different numbers of tandem repeats in the different PRB genes. Variation in the numbers of these repeats is also responsible for length variations in different alleles of the PRB genes. We have determined a probable evolutionary history of the human PRP gene family by comparing the nucleotide sequences of the six PRP genes. The present-day six PRP loci probably evolved from a single ancestral gene by four sequential gene duplications, leading to six genes that fall into three subsets, each consisting of two genes. During this evolutionary process, multiple rearrangements and gene conversion occurred mainly in the region from the 3 end of IVS2 and the 3 end of exon 3.     

人体β-珠蛋白基因5’旁侧调控元件与不同发育时期调控因子的相互作用

人β-珠蛋白基因主要在成年期的骨髓中表达,在胎儿肝,成年肝和K 562细胞中则处于关闭状态。凝胶电泳阻抑法分析发现,在人胎儿肝,成年肝及K 562细胞的核蛋白抽提物中存在着不同的与β-珠蛋白基因5'旁侧调控元件(-372到-194 bp)相结合的红系组织特异性的调控因子。竟争试验的结果表明,成年肝和K 562细胞中的调控因子与β-珠蛋白基因5'旁侧调控元件相互作用的方式具有一定的相似性,这两种细胞的调控因子既结合于负调控区(NCR 2)也结合于正调控区,说明两种细胞中β-珠蛋白基因的关闭机制可能是相似的。胎儿肝的核蛋白因子只结合于负调控区,推测在胎儿期存在独特的关闭机制。     

Cell separation from high cell density broths of Alcaligenes eutrophus by using a coagulant

Summary Alcaligenes eutrophus was successfully recovered from high cell density broths by pre-treatment with polyaluminium hydroxide chloride silicate as a coagulant at 36–90 mg Al/l. The optimum pH range for cell coagulation was 10–12. Subsequent centrifugation (45×g) and filtration (pore size 0.5 mm) gave a cell recovery of higher than 90%. The energy demand for cell recovery with the coagulant was only 3–11% of that without it.     

多元方差分析中的单一自由度独立比较

本文根据一元方差分析的单一自由度比较原理提出了多元方差分析中的单一自由度比较方法,以用于各种平衡试验设计中具多个变量的处理间多重比较．     

Trypsin and forskolin decrease the sensitivity of L-type calcium current to inhibition by cytoplasmic free calcium in guinea pig heart muscle cells.

A key feature of trypsin action on ionic membrane currents including L-type Ca2+ current (ICa) is the removal of inactivation upon intracellular application. Here we report that trypsin also occludes the resting cytoplasmic free Ca2+ ([Ca2+]i)-induced inhibition of peak ICa in isolated guinea pig ventricular cardiomyocytes, using the whole-cell patch clamp in combination with the Fura-2 ratio-fluorescence technique. The effectiveness of trypsin to guard ICa against [Ca2+]i-induced inhibition was compared with that of forskolin, as cAMP-dependent phosphorylation had been suggested to confer protection against [Ca2+]i-induced inactivation. Intracellular dialysis of trypsin (1 mg/ml) augmented ICa by 7.2-fold, significantly larger than the threefold increase induced by forskolin (3 microM). Forskolin application after trypsin dialysis did not further enhance ICa. An increase in [Ca2+]i from resting levels (varied by 0.2, 10, and 40 mM EGTA dialysis) to submicromolar concentrations after replacement of external Na+ (Na(o)+) with tetraethylammonium (TEA+) resulted in monotonic inhibition of control ICa, elicited from a holding potential of -40 mV at 22 degrees C. AFter trypsin dialysis, however, ICa became less sensitive to submicromolar [Ca2+]i; the [Ca2+]i of half-maximal inhibition (K0.5, normally around 60 nM) increased by approximately 20-fold. Forskolin also increased the K0.5 by approximately threefold. These and accompanying kinetic data on ICa decay are compatible with a model in which it is assumed that Ca2+ channels can exist in two modes (a high open probability "willing" and a low open probability "reluctant" mode) that are in equilibrium with one another. An increase in [Ca2+]i places a larger fraction of channels in the reluctant mode. This interconversion is hindered by cAMP-dependent phosphorylation and becomes nearly impossible after tryptic digestion.     

Crystallization,molecular replacement solution,and refinement of tetrameric β-amylase from sweet potato

Sweet potato β-amylase is a tetramer of identical subunits, which are arranged to exhibit 222 molecular symmetry. Its subunit consists of 498 amino acid residues (Mr 55,880). It has been crystallized at room temperature using polyethylene glycol 1500 as precipitant. The crystals, growing to dimensions of 0.4 mm × 0.4 mm × 1.0 mm within 2 weeks, belong to the tetragonal space group P4₂2₁2 with unit cell dimensions of a = b = 129.63 Å and c = 68.42 Å. The asymmetric unit contains 1 subunit of β-amylase, with a crystal volume per protein mass (V_M) of 2.57 ų/Da and a solvent content of 52% by volume. The three-dimensional structure of the tetrameric β-amylase from sweet potato has been determined by molecular replacement methods using the monomeric structure of soybean enzyme as the starting model. The refined subunit model contains 3,863 nonhydrogen protein atoms (488 amino acid residues) and 319 water oxygen atoms. The current R-value is 20.3% for data in the resolution range of 8–2.3 Å (with 2 σ cut-off) with good stereochemistry. The subunit structure of sweet potato β-amylase (crystallized in the absence of α-cyclodextrin) is very similar to that of soybean β-amylase (complexed with α-cyclodextrin). The root-mean-square (RMS) difference for 487 equivalent Cα atoms of the two β-amylases is 0.96 Å. Each subunit of sweet potato β-amylase is composed of a large (α/β)₈ core domain, a small one made up of three long loops [L3 (residues 91–150), LA (residues 183–258), and L5 (residues 300–327)], and a long C-terminal loop formed by residues 445–493. Conserved Glu 187, believed to play an important role in catalysis, is located at the cleft between the (α/β)₈ barrel core and a small domain made up of three long loops (L3, L4, and L5). Conserved Cys 96, important in the inactivation of enzyme activity by sulfhydryl reagents, is located at the entrance of the (α/β)₈ barrel. © 1995 Wiley-Liss, Inc.     

四川地区幼儿和学龄前儿童的鼻部测量

本文报告１１１６例四川地区幼儿和学龄前儿童（２－７岁）鼻部９项指标的测量均数,性差及年龄发育特点。性差：仅鼻凹鼻底距４－６．５岁等少数指标部分年龄段男女性间出现显著性划异（男＞女）。此外各项指标的绝大多数年龄段男女性间无显著性差异。年龄发育：９项测量指标中７项的生长曲线随年产长而上升,数值随年龄增大,并有１－２个发育高峰;提示鼻部发育具有阶段性;２项指标的曲线随年龄增长变化较小。４项指标男女性的曲     

Angiotensin-converting enzyme inhibitory and antihypertensive activities of pivalopril (RHC 3659-(S))

Pivalopril (RHC 3659-(S); (S)-N-cyclopentyl-N-(2-methyl-3-pivaloylthiopropionyl) glycine) is a new compound with a hindered sulfur group that has been compared to captopril for oral angiotensin-converting enzyme (ACE) inhibition in rats and dogs and antihypertensive activity in rats. In separate groups of conscious normotensive rats, pivalopril (0.03-1.0 mg/kg, orally [p.o.]) produced a dose-related antagonism of angiotensin I (AngI)-induced pressor effects. The ED50 for pivalopril and captopril was 0.1 mg/kg. In conscious normotensive dogs, pivalopril (incremental doses of 0.01-1.0 mg/kg, p.o.) produced a dose-related antagonism of AngI pressor effects. The ED50 was 0.17 mg/kg for pivalopril and 0.06 mg/kg for captopril. At equieffective doses the two compounds had similar durations of action. In sodium-deficient, conscious spontaneously hypertensive rats (SHR), pivalopril (1-100 mg/kg, p.o.) produced a dose-related reduction in mean arterial pressure. The potency and duration were similar to those of captopril. In the sodium-replete SHR, 5 days of oral dosing with pivalopril, 100 mg/(kg . day), decreased mean arterial pressure more effectively than captopril, 100 mg/(kg . day). No tolerance developed to the antihypertensive effect of either drug. It is concluded that pivalopril is a potent, orally effective ACE inhibitor and antihypertensive agent.