Indonesian Throughflow in an eddy-resolving ocean model

The performance of the eddy-resolving LICOM2.0 in simulating the Indonesian Throughflow has been evaluated against the INSTANT data in the present study. The mean vertical structures of the along strait velocities are simulated well in LICOM2.0, but the large velocities at the bottom of the Lifamatola Passage and the Timor Passage cannot be reproduced by LICOM2.0. The causes are considered to be both the errors in the topography and the tidal mixing at the bottom. Despite several biases in the mean velocities, the mean inflow and outflow volume transports in LICOM2.0 are almost identical to the INSTANT data. Com- pared with the lower resolution LICOM, the most significant improvement is the better simulation of the partitions of the inflow and outflow transports in individual straits. The outflow for low-resolution LICOM is mainly through the Ombai and Lombok Strait, whereas that for LICOM2.0 is mainly through the Timor Passage. The variability of the vertical structure of velocities and the volume transport are also investigated, LICOM2.0 overestimates the magnitude of the upper-layer currents and the amplitude of the variation. We also found that the largest correlation coefficient occurs in the shallowest strait, the Lombok, whereas the lowest occurs in the Timor Passage, especially in the upper layer. The latter may be caused by the unrealistic transport through the Torres Strait in LICOM2.0.     

A haemoglobin switching activity modulates hereditary persistence of fetal haemoglobin

During human development there is a switch from fetal to adult haemoglobin formation, reflecting the differential expression of fetal (G gamma and A gamma) and adult (beta and delta) globin genes. Mutations that inhibit this switch produce variants of the syndrome of hereditary persistence of fetal haemoglobin (HPFH). Adult heterozygotes for these mutants produce 15-30% fetal haemoglobin (HbF) in their red cells. The general assumption is that the mutations result in a permanent switching on of gamma-globin genes. Here, however, we show that fetal globin expression can be turned off in cultures of HPFH cells by an uncharacterized factor in fetal sheep serum. This is the first demonstration that mutations affecting the developmental expression of globin genes can be modulated by exogenous factors. The findings raise the possibility that the phenotype of HPFH is not simply the direct result of mutations in or around globin genes but the consequence of the mutations on the interaction of globin genes with trans-acting regulatory factors.     

印尼中立主义外交初探

中立主义是冷战期间印尼外交政策的基本指导思想。印尼中立外交的特点是长期中立,国内政治体制的变动并没有动摇其中立主义的外交基石。中立主义外交既是印尼自身的地缘位置和政治文化影响的结果,又与印尼的国内政治需求存在着密切的联系。     

印尼中立主义外交初探

中立主义是冷战期间印尼外交政策的基本指导思想。印尼中立外交的特点是长期中立，国内政治体制的变动并没有动摇其中立主义的外交基石。中立主义外交既是印尼自身的地缘位置和政治文化影响的结果，又与印尼的国内政治需求存在着密切的联系。     

印度尼西亚地区南岛语民族的形成初探

南岛语民族是一个重要的民族群体,这个民族群体主要分布在东南亚的海岛地区,是海岛地区的主体民族。但研究表明,这个民族群体并不是当地的土著,而是后来才迁徙过来的。在南岛语民族先民迁徙的过程中,他们也来到了今天的印度尼西亚地区。先后迁徙到印度尼西亚群岛的南岛语民族的先民,在以后的发展过程中,由于地理隔绝,形成了诸多新的民族集团或支系。     

A point mutation in the A gamma-globin gene promoter in Greek hereditary persistence of fetal haemoglobin

Hereditary persistance of fetal haemoglobin (HPFH) is a benign condition characterized by the production in adulthood of more than 1% fetal haemoglobin (HbF, alpha 2 gamma 2) in the absence of erythropoietic stress. Several genetic types have been discerned based on the level of HbF produced, the relative contributions of the duplicated fetal (G gamma and A gamma) globin genes, and the presence or absence of deletions involving the beta and delta genes in cis to the mutation. Greek HPFH is a non-deletion variety in which heterozygotes produce 10-20% HbF, predominantly due to overproduction of the A gamma chain. We have cloned a 40-kilobase (kb) region of the beta-globin cluster from a Greek HPFH allele and report here that a point mutation (G----A) occurs 117 base pairs (bp) 5' to the cap site of the A gamma-globin gene, just upstream of the distal CCAAT sequence. The corresponding region of the G gamma-globin gene is normal. We discuss the implications of this finding for the developmental regulation of globin gene expression.     

Electrostatic interactions in the assembly of haemoglobin

Haemoglobin is the prototype of an allosteric protein in which cooperative behaviour depends on interaction between unlike subunits. Here we present haematological and biochemical evidence that electrostatic interactions are an important determinant of haemoglobin assembly. Individuals heterozygous for positively charged beta-globin variants have a significantly lower proportion of abnormal haemoglobin than those with negatively charged variants. Moreover, these differences become more pronounced when alpha-thalassaemia is also present. Kinetic experiments using isolated chains indicate that the rate of assembly of the heterotetramer is influenced by alterations in surface charge. A simple electrostatic model is proposed in an attempt to explain these haematological and experimental findings.