Non-reciprocal cross-incompatibility in Trichogramma deion

In non-reciprocal cross-incompatibility (NRCI), the crossing of a female of a strain A with a male of a strain B results in hybrid offspring, whereas the reciprocal cross produces few or no hybrids. Only females are of hybrid origin in Hymenoptera because they arise from fertilized eggs; males arise from unfertilized (haploid) eggs. Crosses between many strains of Trichogramma deion showed some degree of NRCI. Crosses between a T. deion culture collected in Seven Pines, California (SVP) with one from Marysville, California (MRY) showed an extreme form of NRCI in which practically no female offspring was produced when MRY females were crossed with SVP males. The reciprocal cross produced a close to normal proportion of female and male offspring. Detailed studied of this cross indicated that 1) the female offspring produced in the compatible interstrain cross were not the result of parthenogenesis but were true hybrids, 2) the incompatible interstrain cross did not produce female offspring because fertilized eggs died during development, 3) the death of these eggs could not be prevented by either antibiotic or temperature treatment, 4) cytoplasmically inherited factors causing NRCI could be discounted because backcrossed females with the genome of MRY and the cytoplasm of SVP, exhibit the NRCI relationship characteristic of their genome. Therefore the NRCI between these strains appears to be caused by a modification coded for by the nuclear genes of MRY that results in incompatibility when SVP sperm fertilizes MRY eggs. In addition the level of incompatibility in crosses between the SVP females and MRY males is temperature sensitive, the higher the rearing temperature the lower the level of compatibility.     

Meteorological factors and the time of onset of chest pain in acute myocardial infarction

Analysis of the time of onset of chest pain in 2254 patients with a myocardial infarction admitted to a coronary care unit in Leicester during a 10-year period shows an association with temperature and humidity. During both the most cold and humid times of the year, the relationship is a strong one. A generalized linear model with a log link was used to fit the data and the backward elimination selection procedure suggested a humid, cold day might help to trigger the occurrence of myocardial infarction. In addition, cold weather was found to have a stronger effect on the male population while those men aged between 50 and 70 years were more sensitive to the effect of high humidity.     

Early after-depolarisations induced by noradrenaline may be initiated by calcium released from sarcoplasmic reticulum

We investigated the effect of 10^–8 M noradrenaline (NA) on [Ca²⁺], and electrical activity of single myocytes of guinea-pig ventricular myocardium loaded with Indo 1-AM. Membrane potential was recorded by means of the patch electrode and patch amplifier set to the current clamp mode. Cells were stimulated at a rate of 30/min by 3 ms pulses of the current injected through the recording electrode. Superfusion of NA resulted in slight shortening of action potentials (APs), increase in rate of rise and amplitude of the respective Ca²⁺ transients, and appearance of secondary Ca²⁺ transients of two kinds: 1. appearing before repolarisation of AP and decay of the preceding Ca²⁺ transient were completed and 2. appearing between the APs. We named them early after-transients (EAT) and delayed after-transients (DAT), respectively. Without any additional intervention EATS caused some prolongation of APs duration and DATs resulted in subthreshold delayed after-depolarisations (DADS). When sarcolemmal K⁺ conductance was decreased by tetraethylammonium (TEA) in the patch electrode or 20 M BaCl₂ in the Tyrode solution, EATs initiated early after depolarizations (EADs) and DATs initiated suprathreshold DADs triggering full-sized APs. Superfusion of 30.0 mM Na⁺ (replaced with LiCl) resulted in reduction of AP duration by -70% and appearance of DATs. Also, the frequent multiple oscillations of Ca ²⁺ concentration were often observed. Neither DATs nor the oscillations had any affect on electrical activity of the cells. Their electrogenicity could not be increased by TEA or 20.0 M Ba²⁺. EATs and DATs and their respective EADs and DADs could not be initiated by NA or low Na⁺ superfusion in the cells pretreated with 2 × 10^–7 M thapsigargin, a selective blocker of Ca²⁺-ATPase of sarcoplasmic reticulum (SR). We conclude that in contrast to the current hypothesis, EADs can be initiated by Ca²⁺ released early in the cardiac cycle from the overloaded SR, and that electrogenicity of both types of Ca²⁺ oscillations critically depends on the sarcolemmal K⁺ conductance.     

Enzyme organization and stability of metabolic pathways: A comparison of various approaches

The aim of this paper is to compare various methods for the quantification of metabolic pathways dynamics. A Yates-Pardee metabolic pathway with enzyme organization, i.e. with spatial localization of the enzymes in a specific cellular compartment, was studied using: (i) the classical Henri-Michaelis-Menten (HMM) equations, (ii) linearization of the HMM equations in the vicinity of a steady state (linearized formalism), and (iii) Biochemical Systems Theory formalism (BST formalism). It is shown that transient solutions computed via either the linearized formalism or the BST formalism can greatly differ from transient solutions computed with the HMM equations. However, in the studied example, results remain qualitatively the same for the three formalisms. This suggests that the study of the topology of the system may give useful insights into the metabolic pathways dynamics.     

Characterization of a Kinesin-Related Gene ATSV, within the Tuberous Sclerosis Locus (TSC1) Candidate Region on Chromosome 9Q34

In the search for candidate genes for the tuberous sclerosis (TSC1) disease locus on chromosome 9q34, we have isolated an overlapping series of 22 plasmid and phage cDNA clones covering nearly 7 kb and with an open reading frame of 5070 bp encoding a protein of 1690 amino acids. The putative protein product is a member of the kinesin superfamily and is homologous to the mouse KIF1A and theCaenorhabditas elegansunc-104 genes. Both KIF1A and unc-104 function in the anterograde axonal transport of synaptic vesicles. The human homolog is therefore termed H-ATSV (axonal transporter of synaptic vesicles, HGMW-approved nomenclature ATSV) Screening of DNA from 107 tuberous sclerosis patients and 80 unaffected individuals with H-ATSV cDNA probes by pulsed-field gel electrophoresis/Southern blotting following digestion by rare-cutting methylation-sensitive restriction enzymes showed variant banding patterns in three patients with tuberous sclerosis. However, further analysis indicated that these variant fragments represent a rare polymorphism probably associated with methylation of clustered restriction sites. There is no evidence to support H-ATSV as a candidate gene for TSC1.     

A Gene for Autosomal Dominant Congenital Nystagmus Localizes to 6p12

Congenital nystagmus is an idiopathic disorder characterized by bilateral ocular oscillations usually manifest during infancy. Vision is typically decreased due to slippage of images across the fovea. As such, visual acuity correlates with nystagmus intensity, which is the amplitude and frequency of eye movements at a given position of gaze. X-linked, autosomal dominant, and autosomal recessive pedigrees have been described, but no mapping studies have been published. We recently described a large pedigree with autosomal dominant congenital nystagmus. A genome-wide search resulted in six markers on 6p linked by two-point analysis at θ = 0 (D6S459, D6S452, D6S465, FTHP1, D6S257, D6S430). Haplotype analysis localizes the gene for autosomal dominant congenital motor nystagmus to an 18-cM region between D6S271 and D6S455.     

Effects ofPax3Modifier Genes on Craniofacial Morphology, Pigmentation, and Viability: A Murine Model of Waardenburg Syndrome Variation

Waardenburg syndrome type 1 is caused by mutations inPAX3.Over 50 humanPAX3mutations that lead to hearing, craniofacial, limb, and pigmentation anomalies have been identified. APAX3mutant allele, segregating in a family, can show reduced penetrance and variable expressivity that cannot be explained by the nature of the mutation alone. TheMus musculus Pax3mutationSp^d(Splotch-delayed, Pax3[formula]), coisogenic on the C57BL/6J (B₆) genetic background, produces in heterozygotes a white belly spot with 100% penetrance and very few other anomalies. By contrast, manySp^d/+ BC₁progeny [F₁♀Sp^d/+ (♀Sp^d/+ B₆× ♂ +/+Mus spretus) × ♂ +/+ B₆] exhibit highly variable craniofacial and pigmentary anomalies. Of the BC₁Sp^d/+ progeny, 23.9% are estimated to be nonviable, and 32.1% are nonpenetrant for the white belly spot. The penetrance and expressivity of theSp^d/+ genotype are controlled in part by the genetic background and the sex of the individual. A minimum of two genes interact withSp^dto influence the craniofacial features of these mice. One of these genes may be either X-linked or sex-influenced, while the other is autosomal. TheA-locus (Agouti) or a gene closely linked toAalso plays a role in determining craniofacial features. At least one additional gene, possibly theA-locus or a gene linked toA,interacts withSp^dand determines the presence and size of the white belly spot. The viability of BC₁mice is influenced by at least three factors:Sp^d,A-locus alleles or a gene closely linked to theA-locus, and the sex of the mouse. These BC₁mice provide an opportunity to identify genes that interact with and modify the expression ofPax3and serve as a model to identify the genes that modify the expression of humanPAX3mutations.     

Anchor-linked intermediates in peptide amide synthesis are caused by dimeric anchors on the solid supports

Cleavage and kinetic studies have been carried out using commercially obtained H-Tyr(tBu)-5-(4′-aminomethyl-3′,5′-dimethoxyphenoxy)valeric acid-TentaGelS (H-Tyr(tBu)-4-ADPV-TentaGelS) and H-Tyr (tBu)-4-ADPV-Ala-aminomethyl-resin (H-Tyr(tBu)-4-ADPV-AM-resin) prepared from commercially available resin and loaded with commercially available Fmoc-4-ADPV-OH amide anchor. Cleavage with pure trifluoroacetic acid (TFA) gave the intermediate H-Tyr-4-ADPV-NH₂, which was then degraded to H-Tyr-NH₂, and cleavage with TFA/dichloromethane (1:9) yielded H-Tyr-4-ADPV-NH₂ which could be isolated in preparative amounts. Cleavage reactions with ¹⁵N-labelled H-Ala-4-ADPV-[¹⁵N]-Gly-AM-resin yielded the intermediate H-Ala-4-ADPV-NH₂, which contained no ¹⁵N as demonstrated by ¹H-NMR. The analysis of the commercial Fmoc-4-ADPV-OH amide anchor showed the presence of Fmoc-4-ADPV-4-ADPV-OH as an impurity in high amounts. This dimeric anchor molecule is the cause of formation of the anchor-linked peptide intermediate obtained during the cleavage from the resin. The particularly high acid-lability of the amide bond between the two ADPV moieties was utilized to synthesize sidechain and C-terminally 4-ADPV protected pentagastrin on a double-anchor resin, and to cleave it using 5% trifluoroacetic acid in dichloromethane. This method may offer a new way for the synthesis of protected peptide amides with improved solubility to be used in fragment condensation.     

Prise en charge psycho-sexologique du patient impuissant

The symptom of impotence is, in the vast majority of cases, extremely welldefined. However, therapeutic approaches incorporate various strategies, including: andrological, analytical and behavioural. A great advance in recent years was due to the development of “integrative models” such as the “American Model” by Helen Kaplan, the “Geneva Model” of Willy Pasini, and our proposed “Parisian Model”, which is founded on the principles of analytical sexotherapy, and comprises several clearly defined stages. The management of impotence must not be restricted only to pharmacological treatment.     

Complex ecological models with simple dynamics: From individuals to populations

The aim of this work is to study complex ecological models exhibiting simple dynamics. We consider large scale systems which can be decomposed into weakly coupled subsystems. Perturbation Theory is used in order to get a reduced set of differential equations governing slow time varying global variables. As examples, we study the influence of the individual behaviour of animals in competition and predator-prey models. The animals are assumed to do many activities all day long such as searching for food of different types. The degree of competition as well as the predation pressure are dependent upon these activities. Preys are more vulnerable when doing some activities during which they are very exposed to predators attacks rather than for others during which they are hidden. We study the effect of a change in the average individual behaviour of the animals on interspecific relationships. Computer simulations of the whole sets of equations are compared to simulations of the reduced sets of equations.