Worm chromosomes call for recognition!

Many organisms face a dilemma rooted in the unequal numbers of X chromosomes carried by the two sexes and the need to maintain equivalent expression of X-linked genes. Several strategies have arisen to cope with this problem. All rely on accurately targeting epigenetic modifications to entire chromosomes. Targeting results from the action of recognition elements that attract modification and may rely on spreading of modification in cis along the affected chromosome. A recent report describing the first X chromosome recognition element from C. elegans opens the way to defining the relative contributions of these factors to the compensation of X-linked gene expression in worms.1 Extrachromosomal arrays composed of a C. elegans recognition element attract proteins that modify the C. elegans X chromosomes and interact genetically with mutations disrupting compensation. Moreover, examination of X:A translocations provides the first evidence for spreading of modification along C. elegans X chromosomes.     

The distribution of radiation-induced breaks in the chromosomes of irradiated subjects

Distribution of radiation-induced breakpoints in chromosomes and its bands in persons recovered from acute radiation sickness and personnel from Chernobyl NPP were investigated using G-banding staining. The frequency of damaged bands and breakpoints in groups exposed to radiation was significantly higher as compared with the control group. It was shown that in exposed to radiation persons damage depends on its length. Most frequently damaged bands in the observed groups were determined. The G-negative bands and telomeres of chromosomes were more sensitive to radiation.     

Automatic karyotyping of plant chromosomes by imaging techniques

Chromosomes of Crepis capillaris (L.) Wallr. were analyzed using a newly developed chromosome image analyzing system, CHIAS-mini. The CHIAS-mini is a desktop system which consists of an ordinary 16-bit personal computer and an image processor as the main frames. Data acquisition, karyotyping and idiogramming of the plant chromosomes were automatically carried out with some manual interaction. The data obtained were comparable to those obtained manually and by a standard image analyzer already developed.     

Apoptosis preferentially eliminates irradiated g0 human lymphocytes bearing dicentric chromosomes

G(0) human peripheral blood lymphocytes were X-irradiated to determine whether there is a direct relationship between radiation-induced dicentric chromosomes and the triggering of apoptosis. Immediately after X-ray exposure, control and irradiated lymphocytes were analyzed for viability, apoptosis and chromosome damage using the premature chromosome condensation technique. A batch of lymphocytes was kept in liquid holding for 48 h and then loaded on Ficoll-Paque medium to separate apoptotic (high-density) and normal (normal-density) cells. Then the same end points were analyzed in high-density and normal-density fractions of control and irradiated lymphocytes. After 48 h of liquid holding, the majority of apoptotic cells contained dicentric chromosomes. These results demonstrate that in human lymphocytes, the type of chromosome damage influences the induction of programmed cell death and provide direct evidence that cells bearing dicentrics are eliminated by apoptosis. G0 lymphocytes are the most common tissue used in biodosimetry studies, and the amount of chromosomal damage detected depends on the time between exposure and sampling. Since the radiation-induced apoptotic cells show the presence of dicentrics, radiation-induced damage can be underestimated. These results may have relevance in evaluations of the efficacy of radiotherapy based on the frequencies of chromosomal aberrations.     

Automatic target recognition based on cross-plot

Automatic target recognition that relies on rapid feature extraction of real-time target from photo-realistic imaging will enable efficient identification of target patterns. To achieve this objective, Cross-plots of binary patterns are explored as potential signatures for the observed target by high-speed capture of the crucial spatial features using minimal computational resources. Target recognition was implemented based on the proposed pattern recognition concept and tested rigorously for its precision and recall performance. We conclude that Cross-plotting is able to produce a digital fingerprint of a target that correlates efficiently and effectively to signatures of patterns having its identity in a target repository.     

Automatic detection of fragile X chromosomes using an X centromere probe

In order to score for the fragile X syndrome, blood samples are prepared with absorption stain labeling by in situ hybridisation of the X chromosome centromeres. Metaphases are located, digitised at high resolution, and segmented fully automatically. A three stage adaptive classification scheme for labeled X chromosomes is then applied. This consists of a simple box classifier to identify plausible X and false positive X chromosomes, followed by a quadratic discriminant classifier that is re-trained for each sample. The modal number of X chromosomes is then determined for each sample and used to refine the classification. A simple fragile site detector is applied to the distal portion of the detected X chromosome long arms. From the results we estimate computer and operator time requirements for a screening system in which the operator reviews only the apparently fragile X chromosomes detected by the computer.     

Automatic recognition and measurement of butterfly eyespot patterns

A favorite wing pattern element in butterflies that has been the focus of intense study in evolutionary and developmental biology, as well as in behavioral ecology, is the eyespot. Because the pace of research on these bull's eye patterns is accelerating we sought to develop a tool to automatically detect and measure butterfly eyespot patterns in digital images of the wings. We used a machine learning algorithm with features based on circularity and symmetry to detect eyespots on the images. The algorithm is first trained with examples from a database of images with two different labels (eyespot and non-eyespot), and subsequently is able to provide classification for a new image. After an eyespot is detected the radius measurements of its color rings are performed by a 1D Hough Transform which corresponds to histogramming. We trained software to recognize eyespot patterns of the nymphalid butterfly Bicyclus anynana but eyespots of other butterfly species were also successfully detected by the software.     

Automatic recognition of insect sounds using MFCC and GMM

昆虫的运动、取食、鸣叫都会发出声音,这些声音存在种内相似性和种间差异性,因此可用来识别昆虫的种类.基于昆虫声音的昆虫种类自动检测技术对协助农业和林业从业人员方便地识别昆虫种类非常有意义.本研究采用了语音识别领域里的声音参数化技术来实现昆虫的声音自动鉴别.声音样本经预处理后,提取梅尔倒谱系数(Mel-frequency cepstrum coefficient,MFCC)作为特征,并用这些样本提取的MFCC特征集训练混合高斯模型(Gaussian mixture model,GMM).最后用训练所得到的GMM对未知类别的昆虫声音样本进行分类.该方法在包含58种昆虫声音的样本库中进行了评估,取得了较高的识别正确率(平均精度为98.95％)和较理想的时间性能.该测试结果证明了基于MFCC和GMM的语音参数化技术可以用来有效地识别昆虫种类.     

基于MFCC和GMM的昆虫声音自动识别

昆虫的运动、 取食、 鸣叫都会发出声音, 这些声音存在种内相似性和种间差异性, 因此可用来识别昆虫的种类。基于昆虫声音的昆虫种类自动检测技术对协助农业和林业从业人员方便地识别昆虫种类非常有意义。本研究采用了语音识别领域里的声音参数化技术来实现昆虫的声音自动鉴别。声音样本经预处理后, 提取梅尔倒谱系数（Mel frequency cepstrum coefficient, MFCC）作为特征, 并用这些样本提取的MFCC特征集训练混合高斯模型（Gaussian mixture model, GMM）。最后用训练所得到的GMM对未知类别的昆虫声音样本进行分类。该方法在包含58种昆虫声音的样本库中进行了评估, 取得了较高的识别正确率（平均精度为98.95%）和较理想的时间性能。该测试结果证明了基于MFCC和GMM的语音参数化技术可以用来有效地识别昆虫种类。     

Automatic classification of chromosomes as part of a routine system for clinical analysis

A procedure for automatic classification of G-banded human chromosomes has been implemented on a semiautomated system for routine clinical analysis. Chromosomes represented by their density profiles are described by so-called weighted density distributions (WDDs) by application of a number of weighting functions and classified by a parametric discriminant analysis. During 16 mo of routine use of the system, 2,794 metaphases (127,925 chromosomes) from amniotic fluid have been karyotyped by the system with an error rate of 8-9%. This corresponds to 4-5 errors per metaphase. These errors can immediately be corrected by the operator on a displayed karyogram with a light pen.     

Automatic analysis of flow cytometric DNA histograms from irradiated mouse male germ cells

An automatic procedure for recovering the DNA content distribution of mouse irradiated testis cells from flow cytometric histograms is presented. First, a suitable mathematical model is developed, to represent the pattern of DNA content and fluorescence distribution in the sample. Then a parameter estimation procedure, based on the maximum likelihood approach, is constructed by means of an optimization technique. This procedure has been applied to a set of DNA histograms relative to different doses of 0.4-MeV neutrons and to different time intervals after irradiation. In each case, a good agreement between the measured histograms and the corresponding fits has been obtained. The results indicate that the proposed method for the quantitative analysis of germ cell DNA histograms can be usefully applied to the study of the cytotoxic and mutagenic action of agents of toxicological interest such as ionizing radiations.     

Rearrangements between irradiated chromosomes in three-species radiation hybrid cell lines revealed by two-color in situ hybridization

A human-hamster hybrid cell line containing only the human X chromosome (GM06318B) was exposed to 6,000–7,000 rad of X-rays and fused with a mouse cell line (CL1D,TK^-). Three radiation hybrids, LXKC40, LXKC50, and LXKC56, were selected among 39 independent clones containing human material. Two-color in situ hybridization with total genomic DNA probes (cotl human DNA and hamster total genomic DNA) was used to analyse the irradiated chromosome rearrangements. With this three-species model system (human-hamster-mouse) and the chromosome painting process it was possible to determine the origin of each chromosomal fragment in metaphase and interphase. The results obtained indicate preferential rearrangement between irradiated human and hamster chromosomes. Whole, apparently intact hamster chromosomes were observed in all the mitoses. We suggest that these chromosomes could be neoformated from random fragments after irradiation. Hamster and human minichromosomes were also detected. While the integration of human material into the mouse genome was exceptional, the integration of hamster material into mouse chromosomes was more frequent. During interphase the irradiated chromosome domains were often at the periphery of the nucleus. Irradiated material protruded at the periphery of the nuclei. Micronuclei containing hamster material were detected in the vicinity of these protrusions.     

Automatic recognition and annotation of gene expression patterns of fly embryos

Vol. 23, No.