Successful pregnancy in a woman with ovarian failure associated with mutation in the beta-subunit of luteinizing hormone.

BACKGROUND: We report a successful pregnancy in a woman with severe ovarian dysfunction and infertility associated with a variant beta-subunit of luteinizing hormone (LH). METHOD/OUTCOME: A 35-year-old woman consulted our unit for infertility. Laparoscopy and ultrasonography showed obstruction of the right tube and ovulation from the right ovary only. Human menopausal gonadotrophin (hMG) therapy was used for six subsequent cycles, but did not result in conception. Subsequently, marked elevation of follicle-stimulating hormone (FSH) and testosterone, together with polycystic ovary (PCO) were noted. The patient failed to respond to ovarian stimulation by hMG. Severe ovarian dysfunction such as premature ovarian failure (POF) was strongly suspected. Sequence analysis of the LH beta-subunit gene indicated heterozygosity for point mutations Trp(8) to Arg(8) and Ile(15) to Thr(15) in the coding sequence. LH hypersecretion resembling that seen in PCO syndrome was observed. Induction of ovulation by hMG was successful in the first cycle in which the basal LH and FSH were well controlled with gonadotrophin-releasing hormone analog following estrogen-progesterone replacement. She conceived and delivered a healthy male infant at term. CONCLUSION: Clinicians should be clinically aware of patients with immunologically anomalous LH variant who might be at risk of developing ovarian failure within a relatively short time span. Pertinent treatment should be applied without delay in such cases.     

Regulation of meiotic recombination and prophase I progression in mammals.

Meiosis is the process by which diploid germ cells divide to produce haploid gametes for sexual reproduction. The process is highly conserved in eukaryotes, however the recent availability of mouse models for meiotic recombination has revealed surprising regulatory differences between simple unicellular organisms and those with increasingly complex genomes. Moreover, in these higher eukaryotes, the intervention of physiological and sex-specific factors may also influence how meiotic recombination and progression are monitored and regulated. This review will focus on the recent studies involving mouse mutants for meiosis, and will highlight important differences between traditional model systems for meiosis (such as yeast) and those involving more complex cellular, physiological and genetic criteria.     

Ca2+ is Required by Clubroot Resistant Turnip Cells for Transient Increases in PAL Activity that Follow Inoculation with Plasmodiophora brassicae

Phenylalanine ammonia‐lyase (PAL, EC 4.3.1.5) activity in clubroot disease‐resistant turnip calli was transiently increased by 20 h after the inoculation with Plasmodiophora brassicae spores. The magnitude of the increase in PAL activity was four to six times higher than constitutive PAL activity. There was no transient increase in PAL activity in susceptible calli. Preincubation of calli in Ca²⁺‐free medium or the removal of Ca²⁺ from cell surfaces by ethylene glycol bis(2‐aminoethyl ether)‐N,N,N′,N′‐tetraacetic acid‐chelation, completely inhibited induced PAL activity. The influx of exogenous Ca²⁺ into cells appears necessary for this pathogen induced PAL activity. Verapamil and the calmodulin inhibitor W7 almost completely inhibited induced PAL activity at 1 and 0.1 mm , respectively. Neomycin, ruthenium red and (1‐(6‐[(17β‐3‐Methoxyestra‐1,3,5‐(10)‐trien‐17‐yl)amino]hexyl)‐1H‐pyrrole‐2,5‐dione) did not inhibit induced PAL activity. Thus, verapamil and N‐(6‐aminohexyl)‐5‐chloro‐1‐naphthalenesulphonamide hydrochloride‐sensitive Ca²⁺‐mediated signalling process appear necessary for P. brassicae induced PAL activity. As the protein synthesis inhibitor cycloheximide (CHX) blocked the induced increasing PAL activity, de novo synthesis of PAL appears to be required for turnip cell defence reactions against P. brassicae.     

The lactose transport protein is a cooperative dimer with two sugar translocation pathways.

The Major Facilitator Superfamily lactose transport protein (LacS) undergoes reversible self-association in the detergent-solubilized state, and is present in the membrane as a dimer. We determined the functional unit for proton motive force (Deltap)-driven lactose uptake and lactose/methyl-beta-D-galactopyranoside equilibrium exchange in a proteoliposomal system in which a single cysteine mutant, LacS-C67, defective in Deltap-driven uptake, was co-reconstituted with fully functional cysteine-less protein, LacS-cl. From the quadratic relationship between the uptake activity and the ratio of LacS-C67/LacS-cl, we conclude that the dimeric state of LacS is required for Deltap-driven uptake. N-ethylmaleimide (NEM) treatment of proteoliposomes abolished the LacS-C67 exchange activity but left the LacS-cl unaffected. After NEM treatment, the exchange activity decreased linearly with increasing ratios of LacS-C67/LacS-cl, suggesting that the monomeric state of LacS is sufficient for this mode of transport. We propose that the two subunits of LacS are functionally coupled in the step associated with conformational reorientation of the empty binding site, a step unique for Deltap-driven uptake.     

Phase memory relaxation times of spin labels in human carbonic anhydrase II: pulsed EPR to determine spin label location.

Phase memory relaxation times (T(M) or T(2)) of spin labels in human carbonic anhydrase II (HCA II) are reported. Spin labels (N-(1-oxyl-2,2,5,5-tetramethyl-3-pyrrolidinyl)iodoacetamide, IPSL) were introduced at cysteines, by site-directed mutagenesis at seven different positions in the protein. By two pulse electron paramagnetic resonance (EPR), electron spin echo decays at 45 K are measured and fitted by stretched exponentials, resulting in relaxation parameters T(M) and x. T(M) values of seven positions are between 1.6 micros for the most buried residue (L79C) and 4.7 micros for a residue at the protein surface (W245C). In deuteriated buffer, longer T(M) are found for all but the most buried residues (L79C and W97C), and electron spin echo envelop modulation (ESEEM) of deuterium nuclei is observed. Different deuterium ESEEM patterns for W95C and W16C (surface residue) indicate differences in the local water concentration, or accessibility, of the spin label by deuterium. We propose T(M) as a parameter to determine the spin label location in proteins. Furthermore, these systems are interesting for studying the pertaining relaxation mechanism.     

Phylogenetic analysis of the Rhabdocoela (Platyhelminthes) with emphasis on the Neodermata and relatives

Phylogenetic systematic analysis of 24 taxa representing the rhabdocoel platyhelminths, based on a suite of 89 morphological characters, produced two equally parsimonious trees, 181 steps long, with a consistency index (CI) of 0.69 and a rescaled consistency index (RCI) of 0.56, differing only with respect to that portion of the tree containing Umagillidae, Acholadidae, Graffillinae, Pseudograffillinae, Pterastericolidae and Hypoblepharinidae. Our results accommodate all previously proposed sister taxa to the Neodermata in a single clade in which ((Dalyelliidae + Temnocephalida) Typhloplanidae) is the sister group of ((Fecampiidae +  Urastoma ) ( Udonella ((Aspidogastrea + Digenea) (Monogenea (Gyrocotylidea (Amphilinidea + Eucestoda)))))). Bootstrap and jackknife analyses indicate that the groupings of ((Dalyelliidae + Temnocephalida) Typhloplanidae) and of ((Fecampiidae +  Urastoma ) ( Udonella ((Aspidogastrea + Digenea) (Monogenea (Gyrocotylidea (Amphilinidea + Eucestoda)))))) are highly robust, with the latter clade having a CI of 90% and RCI of 82%. Disagreements among previous analyses of these taxa have been due to the influence of missing data for critical characters in key taxa and differences in the taxa analysed, rather than any inherent weakness in the morphological data. Non-phylogenetic systematic approaches to homology assessment and misconceptions regarding phylogenetic systematic methodology are discussed. Recent analyses combining sequence data with a subset of approximately 60% of the morphological characters should be re-assessed using the entire morphological database. Even if Udonella is a monogenean, it is most parsimonious to suggest that the common ancestor of the Neodermata had a vertebrate–arthropod two-host life cycle.     

Exploitation of Arabidopsis-tomato synteny to construct a high-resolution map of the ovatecontaining region in tomato chromosome 2.

High-resolution genetic and physical maps were constructed for the region of chromosome 2 containing the major fruit-shape locus ovate. A total of 3,000 NIL F2 and F3 NILs derived from Lycopersicon esculentum cv. Yellow Pear (TA503) x L. pennellii (a wild tomato) were used to position ovate adjacent to the marker TG645 and flanked by markers TX700 and BA10R (a 0.03-cM interval). BAC libraries and a BIBAC library were screened with the closest marker, TG645. Genetic mapping with the ends of isolated BAC clones revealed that two BAC clones (100 and 140 kb) both contained the ovate locus. Screening of sequences from these BAC clones revealed synteny between this segment of tomato chromosome 2 and the chromosome-4 region of Arabidopsis containing the BAC clone ATAP22. Microsynteny between the two genomes was exploited to find additional markers near the ovate locus. The placement of ovate on a BAC clone will now allow cloning of this locus and, hence, may open the door to understanding the molecular basis of fruit development and also facilitate the genetic engineering of fruit-shape characteristics. This also represents the first time that microsynteny with Arabidopsis has been exploited for positional cloning purposes in a different plant family.     

An effector of Ypt6p binds the SNARE Tlg1p and mediates selective fusion of vesicles with late Golgi membranes.

Membrane traffic requires vesicles to fuse with a specific target, and SNARE proteins and Rab/Ypt GTPases contribute to this specificity. In the yeast Saccharomyces cerevisae, the Rab/Ypt GTPase Ypt6p is required for fusion of endosome-derived vesicles with the late Golgi. We have shown previously that activation of Ypt6p depends on its exchange factor, Ric1p-Rgp1p, a peripheral membrane protein complex restricted to the Golgi. We show here that a conserved trimeric protein complex, VFT (Vps52/53/54), binds directly to Ypt6p:GTP. Localization of VFT to the Golgi requires Ypt6p, but is unaffected in gos1 and tlg1 mutants, in which late Golgi integral membrane proteins, including SNAREs, are mislocalized. The VFT complex also binds directly to the N-terminal domain of the SNARE Tlg1p, both in vitro and in vivo, in a Ypt6p-independent manner. We suggest that the VFT complex links vesicles containing Tlg1p to their target, which is defined by the local activation of Ypt6p.