中国莲的定量染色体图

利用MetaMorph软件定量分析了中国莲(Nelumbo mucifera Gaertn.)每条前中期染色体上(从短臂到长臂)二脒基苯基吲哚(DAPI)荧光强度的变化，结合染色体的相对长度和臂比作为辅助参数，构建了中国莲前中期染色体的定量染色体图．该定量染色体图是实际的前中期染色体的一种直观模式，可识别中国莲基因组中每条染色体以及分析染色体上的异染色质分布，为莲的细胞遗传学研究提供了一种新的方法．     

Genome size,self‐organization and DNA's dark matter

Chromosomes exhibit several features indicating that its spatiotemporal dynamics is self‐organized. It has been recently suggested that a negative correlation between genome size and mean chromosome number would also be a fingerprint of selforganization, related to how human language is organized at the level of words and syllables. However, the vast dominance of non‐coding DNA in eukaryotic genomes should prevent an interpretation of genome/chromosome size based on functional trade‐offs related to information storage and transmission. Moreover, the reported negative correlation is shown to be an inevitable consequence of the definitions of chromosome and genome length and it is thus unrelated to any type of special generative process. © 2010 Wiley Periodicals, Inc. Complexity 16: 20–23, 2010     

The Reserve/Maximum Capacity of Melatonin’s Synthetic Function for the Potential Dimorphism of Melatonin Production and Its Biological Significance in Mammals

In this article, we attempt to classify a potential dimorphism of melatonin production. Thus, a new concept of “reserve or maximum capacity of melatonin synthetic function” is introduced to explain the subtle dimorphism of melatonin production in mammals. Considering ASMT/ASMTL genes in the pseudoautosomal region of sex chromosomes with high prevalence of mutation in males, as well as the sex bias of the mitochondria in which melatonin is synthesized, we hypothesize the existence of a dimorphism in melatonin production to favor females, which are assumed to possess a higher reserve capacity for melatonin synthesis than males. Under physiological conditions, this subtle dimorphism is masked by the fact that cells or tissues only need baseline melatonin production, which can be accomplished without exploiting the full potential of melatonin’s synthetic capacity. This capacity is believed to exceed the already remarkable nocturnal increase as observed within the circadian cycle. However, during aging or under stressful conditions, the reserve capacity of melatonin’s synthetic function is required to be activated to produce sufficiently high levels of melatonin for protective purposes. Females seem to possess a higher reserve/maximum capacity for producing more melatonin than males. Thus, this dimorphism of melatonin production becomes manifest and detectable under these conditions. The biological significance of the reserve/maximum capacity of melatonin’s synthetic function is to improve the recovery rate of organisms from injury, to increase resistance to pathogen infection, and even to enhance their chances of survival by maximizing melatonin production under stressful conditions. The higher reserve/maximum capacity of melatonin synthesis in females may also contribute to the dimorphism in longevity, favoring females in mammals.     

MS-Untersuchung der Leberfunktion mit 15NH3

Dose response curves for lymphocyte chromosome aberration frequencies using X- and gamma radiations became an important and reliable indicators as biological dosimeters especially in radiation accidents and professional over exposures. Nowadays electron beams therapy are frequently used for their advantages in cases of tumours under or near to the body surface. Dose-response curves for these electron beams are rarely published. Human peripheral blood lymphocytes were in vitro irradiated with various low and high doses (0.1 Gy to 4.9 Gy) of 18 MeV electron beam to utilize such a dose-response curve using chromosome aberration frequencies as a biological marker. Then we compared this biological curve with physically obtained curves normally used in planning for radiotherapy treatment. It is interesting to find a significant difference between both of them. The biological curve is generally higher in value and that the aberrations induced by 93% of a dose is significantly higher and deeper in site than those aberrations induced by the 100% dose calculated physically. If the above observation is confirmed by detailed studies, it would be of importance to the radiotherapist to plan for isodose curves according to biological determinations.

Dosis-Wirkungs-Kurven der Mutationsraten von Lymphozyten Chromosomen bei dcr Anwendung von Röntgen- und Gammastrahlen sind wichtige und verläβliche Indikatoren in Form von biologischen Dosimetern, insbesondere bei Strahlenunfällen und bei berufsbedingten Überbestrahlungen. Gegenwärtig werden häufig auch Elektronenstrahlen wegen ihrer Vorteile bei der Therapie von Tumoren unter oder in der Nähe der Körperoberfläche eingesetzt. Dosis- Wirkungs-Kurven für diese Elektronenstrahlen werden nur selten veröffentlicht. Peripherisehe Bhutlymphozyten des Menschen wurden in vitro mit verschiedenen niedrigen und hohen Dosen (0,1 Gy … 4,9 Gy) von IS MeV-Elektronen bestrahlt, um solche Dosis-Wirkungs-Kurven als biologische Anzeiger für die Chromosomen Mutationsraten zu erhalten. Wir haben dann diese biologische Kurve mit physikalisch erhaltenen Kurven verglichen, die normalerweise bei der Planung radiotherapeutischer Behandlungsmaβnahmen verwendet werden. Es ist interessant festzustellen, daβ zwischen diesen beiden Kurven signifikante Unterschiede bestehen. Die biologische Kurve ist im allgemeinen in ihren Werten hölier und die induzierten Mutationsraten bei 93% einer Dosis sind signifikant höher und tiefer am Ort als jene induzierten Mutationsraten, die durch einer 100%ige Dosis physikalisch berechnet wurde. Sollte sich diese Beobachtung durch weitere dedaillierte Studien erhärten, so ist dies von groβer Bedeutung für Radiotherapeuten, die Isodosenkurven nach biologischen Bestimmungen zu planen haben.     

Conformational and Dynamical Properties of the Isolated,Three‐Dimensional Single‐ and Double‐Tethered Polymer Chain on an Infinite Surface

By Monte Carlo simulations we provide insight into the isolated single‐ and double‐tethered (ST and DT) polymer chain attached to an impenetrable surface to elucidate open theoretical questions and guide future experiments investigating the impact of tethering on the genome packaging by concurrent visualisation of multiple loci along the chromosome(s). In the models, either one or both ends (at a grafting distance d) are fixed or the ST and DT chain are “annealed” by permitting the anchor(s) to diffuse laterally along the surface. We analyse chain self‐entanglement, intrachain segment correlations, the relationship between mean square physical distance and corresponding contour length and provide the first report on the diffusion behaviour.

     

AFM images of G1-phase premature condensed chromosomes: Evidence for 30 nm changed to 50 nm chromatin fibers

To gain evidence for 30 nm changed to 50 nm chromatin fibers, we used atomic force microscopy (AFM) to study the ultrastructural organization of G₁-phase premature condensed chromosomes (PCC). The surface of early G₁-phase PCC is smooth and fibrous structures exist around the chromatids. The height of early G₁-phase PCC is about 410 nm and the width is 1.07 ± 0.11 μm (n = 30). At late G₁-phase, the surface becomes globular. The height of late G1-phase PCC is about 370 nm and the width is 845.04 ± 82.84 nm (n = 30). Phase image reveals that early G₁-phase PCC is composed of 50 nm (48.91 ± 6.63 nm, n = 30) chromatin fibers and these 50 nm chromatin fibers tangle together, while late G₁-phase PCC is composed of 30 nm (30.96 ± 4.07 nm, n = 30) chromatin fibers. At high magnification, fibers existing around the chromatids become clear in early G₁-phase PCC. Chromatin fibers revealed by closer view of the end of chromatid are about 50 nm. In late G₁-phase PCC, the surface presents globular structures. The shape of these globular structures is regular and the diameter is 118.96 ± 11.70 nm (n = 30). Our results clearly show that 30 nm chromatin fibers change to 50 nm chromatin fibers in G₁-phase PCC and suggest that 50 nm chromatin fibers are the basic component of the mitotic chromosomes.     

STUDIES ON THE ORIGIN OF B CHROMOSOMES IN RYE

The morphological structure, classification and meiotic behaviour as well as the possible origin of the extra centric fragment produced after intercellular chromatin migration (cytomixis) in pollen mother cells during synizesis in rye have been studied by the squash and Giemsa·C-banding techniques. The results showed that the structures of extra centric fragments are metacentric, submetacentric, telocentric or subtelocentric, being quite different from each other. Their originations are stochastic, because any chromosome can be formed by the fragment. The meiotic behaviour of extra centric fragments is identical with that of B chromosomes. We consider that extra centric fragments are B chromosomes. The fragments originated from the fragmentation of A chromosomes at synizesis during cytomixis. Thus we consider that cytomixis could be one of the origins of B chromosomes.     

Imaging of human meiotic chromosomes by scanning near-field optical microscopy (SNOM)

Centromeres and telomeres are key structures of mitotic and meiotic chromosomes. Especially telomeres develop particular structural properties at meiosis. Here, we investigated the feasibility of scanning near-field optical microscopy (SNOM) for light-microscopic imaging of meiotic telomeres in the sub-hundred nanometer resolution regime. SNOM was applied to visualise the synaptonemal complex (SC) and telomere proteins (TRF1, TRF2) after differential immuno-fluorescent labelling. We tested and compared two different preparation protocols for their applicability in a SNOM setting using micro-fabricated silicon nitride aperture tips. Protocol I consisted of differential labelling of meiotic chromosome cores (SC) by SCP3 immuno-fluorescence and telomeres by TRF1 or TRF2 immuno-fluorescence, while protocol II combined absorption labelling with alkaline phosphatase substrates of cores with fluorescent labelling of telomeres. The results obtained indicate that protocol I reveals a better visualisation of structural (topographic) details than protocol II. By means of SNOM, meiotic chromosome cores could be visualised at a resolution overtopping that of far-field light microscopy.     

水稻间期核、粗线期和有丝分裂中期染色体FISH分辨率的比较

利用水稻第 4染色体上的两个BAC(bacterialartificialchromosome)克隆作为探针 ,对水稻间期核、减数分裂染色体和有丝分裂中期染色体进行了荧光原位杂交 (fluorescenceinsituhybridization ,FISH) 结果表明 ,它们的杂交信号在水稻第 4染色体短臂上 ,有丝分裂中期染色体上两信号完全重叠 ,而在早粗线期染色体上可以分开 已知它们间的遗传距离为 2cM ,在粗线期染色体上两信号点彼此邻近但未重叠 ,两信号点中心的物理距离为 0 .36μm ,在间期核上两个信号点完全分开 ,相距 (2 .0 6± 1.15 ) μm 说明在水稻第 4染色体上 ,减数分裂粗线期FISH可以分辨相距约 2cM的两个标记 讨论了水稻减数分裂粗线期染色体FISH的技术及其优越性     

Chemically induced chromosome damage in early-developing embryos of Anilocra physodes L. (Crustacea,Isopoda) following exposure to bis[Dimethyltin(IV)Chloro]protoporphyrin IX

In order to obtain chromosome preparations from early-developing embryos of Anilocra physodes, a squash technique has been successfully employed. Results gathered after exposure of this material to bis[dimethyltin(IV)chloro]protoporphyrin IX {[(CH₃)₂SnCl]₂ - Protoporphyrin IX} solutions at different exposure times suggest that this chemical complex is capable of producing abnormal metaphase and anaphase figures in proportion to its concentration and not to exposure length. Essentially, all of the chromosome abnormalities are classifiable as chromosome fragments mainly observed at the metaphase stage; chromosome bridges; and large decondensed chromosome regions.