Genome size, karyotype, meiosis and a novel extra chromosome in Torenia fournieri, T. baillonii and their hybrid

Torenia is a suitable model plant to study plant fertilization because of its protruding embryo sac. However, information on the genomes and chromosomes of this species is limited. We determined the genome sizes of T. fournieri Linden and T. baillonii Godefr as 1.71 pg × 10⁸ bp and 1.67 × 10⁸ bp, respectively. The small genome size of these species suggests their superiority as the targets for molecular cloning studies. Furthermore, karyotypes of T. fournieri and T. baillonii were determined using FISH probed with 5S rDNA, 45S rDNA and species-specific centromere repetitive sequences. Although the two species have similar genome size, number of chromosomes, centromere repeats and 5S rDNA loci were varied. Observation of meiosis in the F₁ hybrid revealed that all chromosomes except one of T. fournieri paired well with the chromosomes of T. baillonii throughout the entire length of the chromosomes including species-specific centromeric regions. One exceptional chromosome of T. fournieri behaved as a univalent and was not always required for gametogenesis. The present results provide the basis for the molecular genetics in Torenia.     

Reach to grasp: the natural response to perturbation of object size

This study assessed the reach to grasp movement and its adaptive response to a perturbation of object size. In blocked trials, subjects (n = 12) were instructed to reach 35 cm to grasp and lift a small- (0.7 cm) or large-diameter (8 cm) cylinder. Under an unconstrained condition (condition 1), no instructions as to the type of grasp to adopt were given. Subjects thus naturally used a precision grip (PG) for the small cylinder and whole hand prehension (WHP) for the large cylinder. Under condition 2, subjects were instructed to utilize a PG for grasps of both the large and small cylinders. For condition 3, the instruction was to use WHP irrespective of object size. Kinematic organization was determined with analysis of the recordings of active markers placed on the wrist, thumb, and three fingers. For condition 1 the results showed a temporal arrangement of both components (transport and manipulation) which differed from that of conditions 2 and 3. In perturbed trials, illumination shifted from the small to large cylinder or vice versa. With condition 1, subjects automatically switched from one grasp to another with no or little increase of movement duration. This was generally achieved by an earlier temporal setting of peak wrist deceleration. For conditions 2 and 3, where a change of aperture was required, movement duration was prolonged without adaptation of earlier transport component parameters. It is concluded that the adaptive responses to a change of distal patterning also affect the organization of the proximal component. Assessment of grasps constrained by instructions may lead to interpretations of central control of the reach to grasp movement which differ from those obtained by assessing more natural prehensile patterns.     

Will the new cytogenetics replace the old cytogenetics?

With the advent of array-based comparative genomic hybridization technology, the analog cytogenetic analysis that has been used for the past 100 years could be replaced by the quantitative, microarray-based molecular analysis. Major advantages of the new array-based cytogenetic technologies are the high resolution and the high throughput. This technology is the first to offer an autonomous whole-chromosome analysis in one hybridization reaction for the detection of submicroscopic gains/losses. However, as with any new technology, it needs to be validated with regard to its performance in various applications (e.g. clinical genetic testing and cancer applications), comparative cost, and the data interpretation.     

Comparison of full length sequences of hepatitis B virus isolates in hepatocellular carcinoma patients and asymptomatic carriers of Korea

Relatively few genomic sequences of Korean hepatitis B virus (HBV) isolates are available. Moreover, no comparative study has been made between the full-length genomes of Korean HBV isolates and clinical status. To evaluate mutations in HBV isolates obtained from chronically infected HBV patients in terms of clinical significance, we determined the genomic sequences of HBV isolates obtained from three hepatocellular carcinoma (HCC) patients (He52, He53, and He82) and from three asymptomatic carriers (He74, He100, and He127). A comparison of sequence variations showed that the HBV isolates from the three HCC patients showed higher frequencies of mutation than the isolates from the three asymptomatic carriers. Three characteristic mutation patterns were identified in the HBV isolates from the HCC patients, which distinguished the HBV isolates from the asymptomatic carriers. First, HBV isolates from the three HCC patients both had double mutations in a core promoter (T1762/A1764) and a precore mutation (A1896). Second, although these isolates belonged to genotype C, 11 amino acids deletions in the preS1 region, specific for HBV genotype D, were detected in the isolates of two HCC patients (He52 and He82). Third, mutations (I127T/N, K130M, and V131I) at three codons in the carboxy functional region of X protein were observed in isolates from all three HCC patients. Additionally, phylogenetic analysis based on the entire HBV sequences showed that all six isolates belonged to genotype C2, as do other Korean strains.     

Recently amplified satellite DNA inCallithrix argentata (Primates,Platyrrhini)

A satellite DNA has been cloned from the neotropical primateCallithrix argentata and designated CarB. The presence of the satellite was assayed in New and Old World primates by blot hybridization: CarB is highly amplified in the genomes of all three species belonging to theC. argentata species group (C. argentata, C. emiliae, C. humeralifer), but is either absent, or present in only minor amounts, in other primates, including the closely related species,C. jacchus. A completely sequenced CarB monomeric unit was 1528 bp in length and mapped to the telomeric C-band-positive regions of manyC. argentata species group chromosomes. Sequence data from eight CarB clones indicated an average difference of 3.5% when base substitutions alone were counted. The hybridization and sequence data suggest that this satellite underwent a period of amplification and dispersal in the genome of a recent ancestor of theC. argentata species group.     

从频率因素分析振动对小白鼠体内~（125）Ⅰ－碘化钠的分布影响

本文系统地观察了不同频率的全身振动引起小白鼠对１２５Ｉ－碘化钠的吸收与分布作用。用放射免疫方法测定小白鼠体内不同组织中碘化钠的分布密度（ｃｐｍ／ｋｇ）。结果发现，振动能明显促进小白鼠对碘化钠的吸收速度。其中，心脏组织、肝脏组织、血液和肾脏组织中碘化钠的分布密度较对照组明显增多。且分布密度的大小依赖于振动频率的高低。同时，振动还能加快碘化钠在小鼠体内的耗散过程。     

Involvement of a large inverted repeated sequence

Summary Southern hybridization of the total DNA of Agrocybe aegerita with cloned mitochondrial (mt) probes revealed a sequence homology between two distant mitochondrial restriction fragments. From the mtDNA restriction map and the distribution of restriction sites on the cross-hybridizing mitochondrial fragments, two copies of a large inverted repeated sequence (IR) of 3 kbp were located on the mitochondrial genome. These IR sequences divided the 80 kbp mtDNA into two singlecopy regions of 24 kbp (SSC) and 50 kbp (LSC). For the first time in higher fungi, this IR sequence has been shown to be involved in an intramolecular homologous recombinational event. Such a rearrangement led to an inversion of the orientation of the two unique-copy regions, without any change in mtDNA complexity. The location of the recombinational event was compared with previously reported plant and fungal mitochondrial rearrangements and the potential role of the IR sequence was discussed.     

Maternal transmission of mitochondrial DNA in interspecific hybrids of Populus

Summary Restriction fragment analysis was conducted to investigate the mode of inheritance of mitochondrial (mt) DNA in F₁ progeny of two P. deltoides x P. deltoides, three P. deltoides x P. nigra, and two P. deltoides x P. maximowiczii controlled crosses, and in Populus x canadensis by using 16 restriction endonucleases and two heterologous probes of cloned mtDNA fragments of maize. Five restriction fragment length polymorphisms (RFLPs) of mtDNA differentiated P. deltoides from P. nigra, whereas three RFLPs of mtDNA separated P. deltoides from P. maximowiczii. In all cases, F₁ progeny of P. deltoides x P. nigra, and P. deltoides x P. maximowiczii, crosses had mtDNA restriction fragments of only their maternal P. deltoides parents. P. x canadensis had mtDNA restriction fragments of only P. deltoides. F₁ progeny of intraspecific P. deltoides crosses also had the same mtDNA fragments as their maternal parent. The results clearly demonstrate uniparental-maternal inheritance of the mitochondrial genome in F₁ interspecific hybrids of P. deltoides with P. nigra and P. maximowiczii.     

In vivo and in vitro comparison of fire ant venom and fire ant whole body extract

Thirty-four patients with a history of immediate hypersensitivity to the sting of the imported fire ant were evaluated in a study designed to compare the diagnostic usefulness of fire ant whole body extract (WBE) preparations with that of fire ant venom (IFAV). Ninety-one percent ($\text{31}\text{34}$) of the hypersensitive patients skin tested with IFAV at a maximal concentration of 1:5 × 10³, $\text{v}\text{v}$, demonstrated a wheat equal to or greater than the histamine control. Fifty-three percent ($\text{18}\text{34}$) of the group were skin test positive to a WBE preparation. When the criteria for a positive skin test were relaxed, 82% of the hypersensitive group could be identified with the IFAWBE. A comparison of skin test results in sensitive patients revealed variability in the sensitivity of the WBE preparations utilized in the study. Leukocyte histamine release demonstrated a dose-response release of histamine with both IFAV and SIWBEa preparations. Specific venom antisera produced in rabbits identified a precipitin line of common identity in a gel-diffusion system containing IFAWBE and IFAV. This finding was verified by the competitive inhibition of IFAWBE with IFAV in a solid-phase radioimmunoassay system. Fire ant WBEs contain venom constituents and are effective diagnostic agents in up to 82% of patients with hypersensitivity to the sting of the imported fire ant. Marked variability in the responsiveness of sensitive patients to different WBE preparations mandates standardization of these diagnostic preparations.     

藏汉民族线粒体基因组全序列的比较研究

目的 以藏汉民族线粒体基因组全序列为基础,进行Haplogroup构建和系统发生分析,在全序列水平上比较核苷酸的变异,阐释可能的变异机制和蕴含的生物学意义.方法 采用Applied Biosystems 3730DNA自动测序仪分别对40名藏族和50名汉族的标本进行线粒体DNA序列测定,应用phredPhrap 16.0软件进行全序列拼接,并以rCRS(revised Cambridge Reference Sequence)为标准与测定序列进行比对分析;根据MTTO-MAP的标准,通过Network方法进行Haplogroup构建和系统发生的分析,并结合其它方法对产生的数据进行深入解读.结果 数据分析结果显示:在系统发生上,藏汉民族90个线粒体DNA序列归类到13个Haplogroups,除M9以外,其它各Haplogroup出现频率之间比较差异无统计学意义;通过两个民族的线粒体DNA全序列比对,发现21个分布频率有统计学意义的变异位点,其中的5个为新变异位点;另外,对D-Loop区的5个突变位点进行了单倍型构建,90个标本可分为2种Supertype,发现在藏汉民族之间Supertypel和Supertype 2的分布频率均有统计学意义.结论 藏汉民族在种族起源和系统发生上具有较近的母系遗传关系;在全序列有统计学意义的位点究竟是适应性或者中性选择,抑或是一种病理性突变尚需深入的探讨.