Myotubular Myopathy in a Girl with a Deletion at Xq27-q28 and Unbalanced X Inactivation Assigns the MTMI Gene to a 600-kb Region

A young girl with a clinically moderate form of myotubular myopathy was found to carry a cytogenetically detectable deletion in Xq27-q28. The deletion had occurred de novo on the paternal X chromosome. It encompasses the fragile X (FRAXA) and Hunter syndrome (IDS) loci, and the DXS304 and DXS455 markers, in Xq27.3 and proximal Xq28. Other loci from the proximal half of Xq28 (DXS49, DXS256, DXS258, DXS305, and DXS497) were found intact. As the X-linked myotubular myopathy locus (MTM1) was previously mapped to Xq28 by linkage analysis, the present observation suggested that MTM1 is included in the deletion. However, a significant clinical phenotype is unexpected in a female MTM1 carrier. Analysis of inactive X-specific methylation at the androgen receptor gene showed that the deleted X chromosome was active in ~80% of leukocytes. Such unbalanced inactivation may account for the moderate MTM1 phenotype and for the mental retardation that later developed in the patient. This observation is discussed in relation to the hypothesis that a locus modulating X inactivation may lie in the region. Comparison of this deletion with that carried by a male patient with a severe Hunter syndrome phenotype but no myotubular myopathy, in light of recent linkage data on recombinant MTM1 families, led to a considerable refinement of the position of the MTM1 locus, to a region of ~600 kb, between DXS304 and DXS497.     

Sequencing of double-stranded PCR products

Very often the experimental step following PCR is sequencing of the amplified fragment. Two protocols that allow direct sequencing of a double-stranded PCR product are described. The first involves removal of one strand of the PCR product using an Ml3 single-stranded DNA clone, allowing the second strand to be sequenced. The second protocol involves Maxam-Gilbert chemical sequencing after PCR amplification with one labeled primer. The advantages and disadvantages of the two protocols are compared, but both yield DNA sequence without cloning of the PCR product.     

Resources,attractiveness, family commitment; reproductive decisions in human mate choice

This study of reproductive decisions in human mate selection used data from "lonely hearts" advertisements to examine a series of predictions based on the mate preferences of male and females relating to age; physical appearance; financial condition and socioeconomic status; family commitment and personal traits; short- and long-term mating; and marital status and preexisting children. The sample consisted of 1000 personal advertisements (500 male) placed in two daily, national papers between February and October 1994 in Hungary. The research procedure included a pilot study of 150 advertisers (75 male) to refine the categories examined. Analysis was performed using 1) a matrix with one axis referring to offers and the other to demands of males and females separately; 2) a matrix of offers only to derive correlated traits of claims by males and females; and 3) a matrix with columns describing sex, offers, demands, advertiser's age, and required age and a row for each of the 1000 samples. It was found that men preferred younger mates, while women preferred older ones. Men were more likely to seek physical attractiveness, while women were more likely to seek financial resources (ranked 7th) and high status (ranked 6th). Women strongly preferred male domestic virtue and family commitment, and twice as many women as men demanded long-term relationships. Women more frequently declared preexisting children, and men exhibited a reluctance to accept these children. Both males and females employed "trade-off" strategies, making greater demands if they felt they had attractive offers.     

Crop load affects assimilation rate, stomatal conductance, stem water potential and water relations of field-grown Sauvignon blanc grapevines

The effects of two shoot densities (14 and 44 shoots/vine) andtwo crop levels (one and two clusters/shoot) on gas exchangeand water relations of field-grown Sauvignon blanc (Vitis viniferaL.) were studied in a factorial design over 3 years. The two-clustertreatments had 0.14 MPa higher stem water potential (_stem),1.4 µmol m^–2 s^–1 higher assimilation rate(A), 0.04 mol m^–2 s^–1 higher stomatal conductance(g_s) and 0.008 mol m^–2 s^–1 higher non-stomatal (g_m)conductance. The two-cluster treatments had higher g_s and transpirationrates than the one-cluster treatments, for similar _stem. A quantitativeanalysis suggests that storage capacity cannot account for thesimultaneous increase in g_s and _stem in the two-cluster treatments.Similar g_s-g_m responses were found In the one- and two-clustertreatments, regard less of differences between the treatmentsin g_s-_stem response. Key words: Grapevine, stomatal conductance, assimilation rate, water relations     

Thermal status of wet-suited divers using closed circuit O2 apparatus in sea water of 17–18.5°C

A wet suit may not provide adequate thermal protection when diving in moderately cold water (17–18°C), and any resultant mild hypothermia may impair performance during prolonged diving. We studied heat exchange during a dive to a depth of 5 m in sea water (17–18.5°C) in divers wearing a full wet suit and using closed-circuit oxygen breathing apparatus. Eight fin swimmers dived for 3.1 h and six underwater scooter (UWS) divers propelled themselves through the water for 3.7 h. The measurements taken throughout the dive were the oxygen pressure in the cylinder and skin and rectal temperatures (T _re). Each subject also completed a cold score questionnaire. The T _re decreased continuously in all subjects. Oxygen consumption in the fin divers (1.40 l · min⁻¹) was higher than that of the UWS divers (1.05 l · min⁻¹). The mean total insulation was 0.087°C · m² · W⁻¹ in both groups. Mean body insulation was 37% of the total insulation (suit insulation was 63%). The reduction in T _re over the 1st hour was related to subcutaneous fat thickness. There was a correlation between cold score and T _re at the end of 1 h, but not after that. A full wet suit does not appear to provide adequate thermal protection when diving in moderately cold water. Accepted: 21 January 1997     

Redox-controlled thylakoid protein phosphorylation. News and views

Thylakoid protein phosphorylation regulates state transition and PSII protein turnover under light-dependent redox control via a signal transduction system. The redox-dependent activation/deactivation of the membrane-bound protein kinase(s), mostly localized in the grana partitions, differs for the various phosphoproteins. Reduction of the plastoquinone pool may be sufficient to activate phosphorylation of few of these proteins. Phosphorylation of LHCII, requires the presence of the cytochrome bf complex in an 'activating mode' characterized by the reduction of its high potential path components and ability to interact with a reduced plastoquinol without oxidizing it. Activation and maintenance of this kinase activity is considered to involve alternate interactions with a cytochrome bf in its activating mode and with the substrate PSII(LHCII). The segregation of the thylakoid components into grana and stroma partitions appears to be mandatory for the kinase activation process. The protein substrate specificity and kinetics differs for various kinases. The thylakoid redox-controlled kinase(s) have not yet been isolated. Preparations highly enriched in kinase activity capable to phosphorylate LHCII and PSII core proteins, contain two kinase active bands, resolved by denaturing electrophoresis and renaturation, and having apparent molecular masses of about 53 and 66 kDa. The roughly estimated abundance of these putative kinase(s) in the grana partitions may be compatible with a ratio of kinase(s): PSII(LHCII) dimers:cytochrome bf dimers in the range of 1:60:30 and a ratio of kinase:phosphorylation sites of about 1:2000. Only about 10–20% of these sites are phosphorylated during state transition. The low turnover rate of the LHCII kinase(s) (< 5) may be due to hindrance of the required random lateral migration within the grana domain rich in tightly packed PSII(LHCII) and cytochrome bf complexes.     

No evidence of linkage between the locus for autosomal dominant retinitis pigmentosa and D3S47 (C17) in three Australian families

Summary A linkage analysis has been performed on three Australian families segregating for autosomal dominant retinitis pigmentosa (ADRP). No evidence of linkage has been found in any of the pedigrees studied between the locus D3S47 and the gene for ADRP. The D3S47 locus was found to show very close linkage with the ADRP gene in a large Irish pedigree. Our study together with a similar report on a British family indicates that there is genetic heterogeneity in this disease.     

Differential effects of transforming growth factor-beta and epidermal growth factor on the cell cycle of cultured rabbit articular chondrocytes

We examined the effect of transforming growth factor (TGF-beta) on the proliferative rate and cell cycle of cultured rabbit articular chondrocytes using cell counting, cytofluorometry, and [3H]-thymidine incorporation. In the presence of 2% or 10% FCS (fetal calf serum), TGF-beta at 0.01, 0.1, 1, and 10 ng/ml had an inhibitory effect on cell proliferation after 24 h exposure with a dose dependence only for 2% FCS. Flow cytometric analysis of cell DNA content at that time showed that a high proportion of cells were arrested in late S-phase (SQ or G2Q) in either 2% or 10% FCS-containing medium. In both cases, a disappearance of the cell blockage occurred between 24 and 48 h after TGF-beta addition. However, whereas a stimulation of cell proliferation rate was observed at that time in cultures containing 10% FCS, a dose-dependence inhibition of cell growth was detected, in contrast, for 2% FCS-treated cells. Presence of TGF-beta during the last 24 h was not necessary to release the arrested cells. Furthermore, platelet-poor plasma at 10% produced the same effects as FCS, suggesting that platelet-derived factors, such as platelet-derived growth factor (PDGF), could not be responsible for the release of blocked cells in this case. We compared the effect of TGF-beta to that of epidermal growth factor (EGF), used at an optimal concentration (10 ng/ml). In both slowly growing (2% FCS) and proliferating chondrocytes (10% FCS), EGF caused a significant increase of cell proliferation as early as 24 h. No arrest in late S-phase but an augmentation of the percentage of cells in S- and G2M-phases were observed. When combined, TGF-beta and EGF did not induce synergistic effect on the chondrocyte proliferation, as estimated by cell counting. [3H]-thymidine labeling showed that the factors induced identical maxima of incorporation but the peak occurred earlier for TGF-beta than for EGF (approximately 6 h versus 12 h, respectively). Although both factors induce similar cell-number increases at 48 h in 10% FCS-containing medium, these proliferative effects were due to different actions on the cell cycle. The present study indicates that TGF-beta induces first a recruitment of chondrocytes in noncycling SQ- or G2Q-blocked cells. The, the release of these cells may produce either apparent stimulation of cell proliferation if sufficient levels of an unknown serum factor are present (10% FCS) or an inhibition of growth rate when only reduced amounts of this factor are available (2% FCS).(ABSTRACT TRUNCATED AT 400 WORDS)