Cytological evidence for a complex of species within the taxon Bactrocera tau (Diptera: Tephritidae) in Thailand

Analysis of mitotic karyotypes of wild specimens of larvae of the Bactrocera tea-like fruit flies (Diptera: Tephritidae) in Thailand has revealed seven distinct chromosome forms, based on the amount and distribution of heterochromatin in sex chromosomes and autosomes. Such cytological differences are perfecdy correlated with morphological observations and molecular genetics data. These findings clearly suggest that B. tau is a cluster of at least seven closely related species temporarily designated as species A (= B. tau) , B, C, D, E, F and G. On die basis of the gross quantity of heterochromatin accumulation in the genome, three groups of mitotic karyotypes can be recognized. Group 1 comprises species A and E. Species E specifically occurs only in fruits of Strychnos thorelii while species A attacks many kinds of host plants. Group 2 contains species B, F and G. Species B has been found only in Siphonodon celastrineus fruit, whereas species F and G attack die same host species, the medically important plant, Hydnocarpus anthelminthicus , albeit in different localities. Group 3 includes species C and D, each of which comprises larger amounts of pericentric heterochromatin in all chromosomes than die other two groups. Hence, diese two species are cytologically remote from those of groups 1 and 2. Species C and D occur allopatrically but they attack the same host plant species, Momordica cochinchinensis. Thus, genetic differentiation at the chromosomal level to specific host plant species and geographic isolation seem to play an important role in speciation of members of the B. tau complex.     

ANOLIS SEX CHROMOSOMES ARE DERIVED FROM A SINGLE ANCESTRAL PAIR

To explain the frequency and distribution of heteromorphic sex chromosomes in the lizard genus Anolis, we compared the relative roles of sex chromosome conservation versus turnover of sex‐determining mechanisms. We used model‐based comparative methods to reconstruct karyotype evolution and the presence of heteromorphic sex chromosomes onto a newly generated Anolis phylogeny. We found that heteromorphic sex chromosomes evolved multiple times in the genus. Fluorescent in situ hybridization (FISH) of repetitive DNA showed variable rates of Y chromosome degeneration among Anolis species and identified previously undetected, homomorphic sex chromosomes in two species. We confirmed homology of sex chromosomes in the genus by performing FISH of an X‐linked bacterial artificial chromosome (BAC) and quantitative PCR of X‐linked genes in multiple Anolis species sampled across the phylogeny. Taken together, these results are consistent with long‐term conservation of sex chromosomes in the group. Our results pave the way to address additional questions related to Anolis sex chromosome evolution and describe a conceptual framework that can be used to evaluate the origins and evolution of heteromorphic sex chromosomes in other clades.     

A 3-Mb Sequence-Ready Contig Map Encompassing the Multiple Disease Gene Cluster on Chromosome 11q13.1-q13.3

Despite the presence of several human disease genes on chromosome11q13, few of them have been molecularly cloned. Here, we reportthe construction of a contig map encompassing 11q13.1–q13.3using bacteriophage P1 (P1), bacterial artificial chromosome(BAC), and P1-derived artificial chromosome (PAC). The contigmap comprises 32 P1 clones, 27 BAC clones, 6 PAC clones, and1 YAC clone and spans a 3-Mb region from D11S480 to D11S913.The map encompasses all the candidate loci of Bardet-Biedlesyndrome type I (BBS1) and spinocerebellar ataxia type 5 (SCA5),one-third of the distal region for hereditary paraganglioma2 (PGL2), and one-third of the central region for insulin-dependentdiabetes mellitus 4 (IDDM4). In the process of map construction,61 new sequence-tagged site (STS) markers were developed fromthe Not I linking clones and the termini of clone inserts. Wehave also mapped 30 ESTs on this map. This contig map will facilitatethe isolation of polymorphic markers for a more re.ned analysisof the disease gene region and identi.cation of candidate genesby direct cDNA selection, as well as prediction of gene functionfrom sequence information of these bacterial clones.     

Delimitation ofPelargonium sect.Glaucophyllum (Geraniaceae)

Pelargonium otaviense Knuth andP. spinosum Willd. are excluded from sect.Glaucophyllum, whileP. grandiflorum (Andr.)Willd.,P. patulum Jacq. andP. tabulare (Burm. f.)L'Hérit. of sect.Eumorpha are included. Sect.Glaucophyllum is characterized by green to glaucous vegetative organs and zygomorphic white to pink corolla with five narrow petals. All the species have an identical pollen and chromosome morphology, the same basic chromosome number (x = 11) and similar flavonoid patterns. A close relationship between sect.Glaucophyllum and sect.Pelargonium is indicated by the occurrence of natural hybrids and concordant characters. Isorhamnetin and luteolin have been detected in the genus for the first time.     

Cell Boundary Confinement Sets the Size and Position of the E. coli Chromosome

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细菌漆酶的生物信息学分析

漆酶是一种含铜的多酚氧化酶。本研究利用生物信息学分析工具对细菌的漆酶蛋白序列的基本性质、保守结构域、系统发育树以及结构等进行了分析。所分析细菌主要分布在变形菌门、放线菌和厚壁菌门。细菌漆酶的物理化学性质相似,但不同细菌来源的漆酶之间序列相似性较低,但其仍然具有容易识别的保守结构域特征。二级结构及三级结构具有明显的相似性。细菌漆酶的生物信息分析为其功能研究及在其他微生物中研究该类酶提供了基础。     

RBMX is a novel hepatic transcriptional regulator of SREBP-1c gene response to high-fructose diet

In rodents a high-fructose diet induces metabolic derangements similar to those in metabolic syndrome. Previously we suggested that in mouse liver an unidentified nuclear protein binding to the sterol regulatory element (SRE)-binding protein-1c (SREBP-1c) promoter region plays a key role for the response to high-fructose diet. Here, using MALDI-TOF MASS technique, we identified an X-chromosome-linked RNA binding motif protein (RBMX) as a new candidate molecule. In electrophoretic mobility shift assay, anti-RBMX antibody displaced the bands induced by fructose-feeding. Overexpression or suppression of RBMX on rat hepatoma cells regulated the SREBP-1c promoter activity. RBMX may control SREBP-1c expression in mouse liver in response to high-fructose diet.     

崇明水仙根尖体细胞染色体的观察和核型分析

以崇明水仙(Narcissus tazetta L.var.chinensis Roem.)根尖体细胞为实验材料,对适宜于崇明水仙细胞学研究的前处理液和前处理时间进行了筛选,在此基础上,应用根尖压片法对重瓣花型和单瓣花型崇明水仙体细胞染色体数、核型及倍性进行了比较分析.结果显示:适宜的前处理液是对二氯苯饱和溶液,适宜的前处理时间为12 h.重瓣花型和单瓣花型崇明水仙的染色体核型差异较小,相同点为:不对称二型核型,染色体基数x=10,三倍体,体细胞染色体数2n=3x=30,第7号染色体的短臂具随体,核型均属于"3B"型,臂比大于2的染色体比率为90%.不同点为:重瓣花型的第7号和第8号染色体分别为sm和st型,单瓣花型的第7号和第8号染色体分别为st和sm型;前者的核型不对称系数(76.48%)略小于后者(76.71%);前者的相对长度系数为12L+6M2+12S,后者的相对长度系数为12L+3M1+3M2+12S;前者的最长染色体与最短染色体长度的比值(3.10)略小于后者(3.19).重瓣花型的核型公式为2n=3x=30=15st+15sm(3SAT),单瓣花型的核型公式为2n=3x=30=15st(3SAT)+15sm,崇明水仙根尖体细胞染色体的平均核型公式为2n=3x=30=15st(3SAT)+15sm.根据研究结果初步推测崇明水仙为节段异源三倍体.     

Occlusion in 47,XXY (Klinefelter syndrome) men.

Occlusal morphology of permanent dentitions in 29 men with a 47,XXY chromosome complement (Klinefelter syndrome) was determined from dental casts. The results showed that a relatively frequent occlusal anomaly was mesial molar occlusion. Incisal open bite was also more common than in controls. Based on the present and previous observations of occlusal anomalies in various sex chromosome anomaly groups and normal controls, it is suggested that the presence of the Y chromosome in the genome is at least as important as the X chromosome for the development of harmonious occlusal morphology. The tendency towards sexual dimorphism in occlusal phenotype might result from a differential effect of the X and Y chromosomes on cellular activity which leads to different growth patterns.     

Shaping mitotic chromosomes: From classical concepts to molecular mechanisms

How eukaryotic genomes are packaged into compact cylindrical chromosomes in preparation for cell divisions has remained one of the major unsolved questions of cell biology. Novel approaches to study the topology of DNA helices inside the nuclei of intact cells, paired with computational modeling and precise biomechanical measurements of isolated chromosomes, have advanced our understanding of mitotic chromosome architecture. In this Review Essay, we discuss – in light of these recent insights – the role of chromatin architecture and the functions and possible mechanisms of SMC protein complexes and other molecular machines in the formation of mitotic chromosomes. Based on the information available, we propose a stepwise model of mitotic chromosome condensation that envisions the sequential generation of intra‐chromosomal linkages by condensin complexes in the context of cohesin‐mediated inter‐chromosomal linkages, assisted by topoisomerase II. The described scenario results in rod‐shaped metaphase chromosomes ready for their segregation to the cell poles.