Absence of repetitive DNA sequences associated with sex chromosomes in natural populations of the Trinidad guppy (Poecilia reticulata)

The genus Poecilia has been widely studied as a model for the evolution of sex chromosomes. In the course of molecular studies on population genetic structure and sexual selection in the Trinidad guppy, we examined our preparations for male-linked, repetitive DNA polymorphisms. We have not obtained any evidence of male-specific polymorphisms, in contrast to an earlier study. Our results have significant implications for theories on the evolution of sex chromosomes.Correspondence to: F. Breden     

Genome-Wide and Locus Specific Alterations in CDC73/HRPT2-Mutated Parathyroid Tumors

Mutations in the hyperparathyroidism type 2 (HRPT2/CDC73) gene and alterations in the parafibromin protein have been established in the majority of parathyroid carcinomas and in subsets of parathyroid adenomas. While it is known that CDC73-mutated parathyroid tumors display specific gene expression changes compared to CDC73 wild-type cases, the molecular cytogenetic profile in CDC73-mutated cases compared to unselected adenomas (with an expected very low frequency of CDC73 mutations) remains unknown. For this purpose, nine parathyroid tumors with established CDC73 gene inactivating mutations (three carcinomas, one atypical adenoma and five adenomas) were analyzed for copy number alterations and loss of heterozygosity using array-comparative genomic hybridization (a-CGH) and single nucleotide polymorphism (SNP) microarrays, respectively. Furthermore, CDC73 gene promoter methylation levels were assessed using bisulfite Pyrosequencing. The panel included seven tumors with single mutation and three with double mutations of the CDC73 gene. The carcinomas displayed copy number alterations in agreement with previous studies, whereas the CDC73-mutated adenomas did not display the same pattern of alterations at loci frequently deleted in unselected parathyroid tumors. Furthermore, gross losses of chromosomal material at 1p and 13 were significantly (p = 0.012) associated with parathyroid carcinomas as opposed to adenomas. Quantitative PCR-based copy number loss regarding CDC73 was observed in three adenomas, while all the carcinomas were diploid or showed copy number gain for CDC73 gene. Hypermethylation of the CDC73 gene promoter was not observed. Our data could suggest that CDC73-mutated parathyroid adenomas exhibit a partly unique cytogenetic profile in addition to that of carcinomas and unselected adenomas. Furthermore, CDC73-mutated carcinomas displayed losses at 1p and 13 which are not seen in CDC73-mutated adenomas, making these regions of interest for further studies regarding malignant properties in tumors from CDC73-mutated cases. However, due to the small sample size, validation of the results in a larger cohort is warranted.     

Pre-Stimulus Sham TMS Facilitates Target Detection

Transcranial magnetic stimulation (TMS) allows non-invasive manipulation of brain activity during active task performance. Because every TMS pulse is accompanied by non-neural effects such as a clicking sound and somato-sensation on the head, control conditions are required to ensure that changes in task behavior are indeed due to the induced neural effects. However, the non-neural effects of TMS in the context of a given task performance are largely unknown and, consequently, it is unclear what constitutes a valid control condition. We explored the non-neural effects of TMS on visual target detection. Participants received single pulse sham TMS to each hemisphere at different time points prior to target appearance during a visual target detection task. It was hypothesized that the clicking sound of a sham TMS pulse differentially affects performance depending on the location of the coil and the timing of the pulse.Our results show that, first, sham TMS caused a facilitation of reaction times when preceding the target stimulus by 150, 200, and 250 ms, whereas earlier and later time windows were not effective. Second, positioning the TMS coil ipsilateral instead of contralateral relative to the target stimulus improved reaction times. Third, infrequent noTMS trials that were interleaved with sham TMS trials had oddball-like properties resulting in increased reaction times during noTMS. The clicking sound produced by sham TMS influences task performance in multiple ways. These non-neural effects of TMS need to be controlled for in TMS research and the present findings provide an empirical basis for deciding what constitutes a valid control condition.     

Abnormalities of human sex chromosomes

Summary The cytogenetic study of a pair of identical, mentally-retarded twins with the chromosome complement 48,XXXY is reported, along with extensive clinical and endocrinological studies of one twin.The genetic and clinical features of 30 reported 48,XXXY individuals were summarized and compared to those of 47,XXY and 49,XXXXY individuals. For 47,XXY the mean maternal age clearly is increased; for 48,XXXY it appears definitely but only slightly increased; and for 49,XXXXY it may not be increased at all. Developmental defects, similar in type, appear to be progressively more marked when an additional 1, 2, or 3 X chromosomes are added to the normal male chromosome complement. 47,XXY individuals may be either normal in intelligence or mentally retarded, whereas severe mental retardation has been present in all those with the complements 48,XXXY and 49,XXXXY.The interesting suggestion of increased twining associated with poly-X male complements is noted.

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Zusammenfassung Die cytogenetische Untersuchung eines Paares eineiiger, geistig zurückgebliebener Zwillinge mit dem Chromosomenstatus 48,XXXY wird dargestellt; bei dem einen Paarling konnten außerdem ausgedehnte klinische und endokrinologische Studien durchgeführt werden.Außerdem wurden die genetischen und klinischen Merkmale der 30 bekannten Fälle mit 48,XXXY dargestellt und mit denen von Patienten mit 47,XXY und mit 49,XXXXY verglichen. Bei Fällen mit 47,XXY ist das mütterliche Alter deutlich erhöht; bei 48,XXXY ist es eindeutig, aber nur leicht erhöht; es sieht so aus, als ob es für 49,XXXXY überhaupt nicht erhöht wäre. Defekte der Entwicklung, die dem Typ nach ähnlich sind, scheinen dem Ausmaß nach desto mehr ausgeprägt zu sein, je mehr X-Chromosomen zusätzlich bei dem normalen männlichen Chromosomensatz vorhanden sind. 47,XXY Individuen können entweder schwachsinnig sein oder eine normale Intelligenz haben; dagegen zeigten alle Fälle mit 48,XXXY und 49,XXXXY einen schweren Schwachsinn.Es wird die interessante Frage aufgeworfen, ob die Zwillingshäufigkeit bei Poly X-Männern erhöht ist.

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Research supported by grants HD 04134, HL 09011, RR-47, AM-11105, and TIAM 53950-11 from the National Institutes of Health.     

The incertae sedis <Emphasis Type="Italic">Carpathoporella</Emphasis> Dragastan, 1995, from the Lower Cretaceous of Albania: skeletal elements (sclerites,internodes/branches,holdfasts) of colonial octocorals

The incertae sedis Carpathoporella Dragastan, 1995, reported from the Lower Cretaceous of the Western Tethyan domain, is usually interpreted as remains of calcareous algae (Dasycladales or Characeae). New thin-section material from the Aptian of Albania sheds light not only on its biogenic nature but also on the morphological variability of this taxon. In fact, Carpathoporella represents the debris of colonial, bushy, most likely gorgonid octocorals with tuberculated spheroids that may be fused at least near the basal root-like holdfast. Colony branching originates from longitudinally grooved calcareous branches or internodes. Possible relationships to other Upper Cretaceous to Palaeogene genera are discussed and a revised critical inventory of Cretaceous octocorals is presented. Due to the evidenced morphological features, Carpathoporella could either represent an ancestral isidid octocoral of the order Alcyonacea such as Moltkia Steenstrup or, due to the likely primary aragonitic skeletal mineralogy, a representative of Epiphaxum Lonsdale of the order Helioporacea. Due to morphological analogies, the new combination Carpathoporella elliotti (Radoičić) is proposed. In any case, the Lower Cretaceous record from Tethyan peri-reefal shallow-water carbonates is highlighted since numerous skeletal findings of fossil gorgonid Octocorallia were so far only known from Upper Cretaceous and younger strata of outer shelf environments of the boreal realm. The origin of deep-water Upper Cretaceous octocorals from Lower Cretaceous shallow-water taxa such as Carpathoporella is proposed as a possible further example of onshore/offshore evolutionary pattern.     

Thermal responses of an insect subjected to temperature variations

Temperature responses of the cockroach, Blaberus craniifer, to rapid changes of ambient temperature (T_a) have been studied. In static conditions at T_a = 27°C the body-to-ambient temperature difference was only 0.10 ± 0.07°C. Two test situations were used, either a ramp increase of T_a from 27 to 31°C (0.1°C/min) or “step” changes from 27 to 28°C and back (0.5°C/min). In both cases body temperature closely followed Newtonian model, the body time constants measured in various conditions being very similar: 543 ± 99 sec in ramp tests, 550 ± 68 sec and 542 ± 124 sec in rising and falling step tests respectively. It is concluded that in spite of evident differences between the cockroach and an inert solid, the Newtonian model adequately represents the thermal responses of this insect to moderate changes in ambient temperature.     

Über Duplicitas anterior,posterior und posterior,partim cruciata bei Triton

Ohne Zusammenfassung