Trisomy 20p derived from a maternal pericentric inversion and brachymesophalangy of the index finger

The article brings to light the very first case of trisomy 20p resulting from a maternal pericentric inversion in a 2 1/2-year old boy. The study outlines the characteristic clinical features of the syndrome, i.e. round face, upslanting palpebral fissures, microretrognathia, normal growth, slight psycho-motor retardation and congenital heart defects. The association of the der(20) inv(20) (p112q133) mat and brachymesophalangy of index ("Mohr-Wriedt" type of brachydactyly) enables the authors to suggest that chromosome 20 may be held responsible for this particular malformation.     

Development of genetic sexing strains in Lepidoptera: from traditional to transgenic approaches

The sterile insect technique (SIT) is currently being used for the control of many agricultural pests, including some lepidopteran species. The SIT relies on the rearing and release of large numbers of genetically sterile insects into a wild population. The holokinetic chromosomes of Lepidoptera respond differently to radiation than do species where there is a localized centromere. This difference has enabled a variation of the SIT to be developed for Lepidoptera where a substerilizing dose of radiation is given to the insects before their release with the result that a certain level of sterility is inherited by the F1 offspring. The development of genetic sexing strains for fruit flies, enabling the release of males only, has resulted in enormous economic benefits in the mass rearing and has increased the efficiency of the field operations severalfold. This article outlines Mendelian approaches that are currently available to separate large numbers of males and females efficiently for different lepidopteran species and describes their difficulties and constraints. Successful transgenesis in several lepidopteran species opens up new possibilities to develop genetic sexing strains. The proposal to develop genetic sexing strains described in this article takes advantage of the fact that in Lepidoptera, the female is the heterogametic sex, with most species having aWZ sex chromosome pair, whereas the males are ZZ. This means that if a conditional lethal gene can be inserted into the W chromosome, then all females should die after the application of the restrictive condition. The assumptions made to accommodate this model are discussed, and the advantages to be gained for control programs are elucidated.     

Genetic control of pest Lepidoptera: construction of a balanced lethal strain in Ephestia kuehniella

A genetic method for the suppression of Lepidopteran pests has been investigated in the Mediterranean flour moth, Ephestia kuehniella Zeller. The method is based on the release of males trans-heterozygous for two sex-linked recessive lethal mutations (SLRLMs). In this paper, characteristics of 16 new SLRLMs are presented. The construction of a balanced lethal strain, BL-2, which was the last step to develop the method, is reported. Males of the strain are balanced for two non-allelic SLRLMs, sl-2 and sl-15. Females carry either sl-2 or sl-15 in their Z chromosome and the T(W;Z)2 translocation on their W chromosome. The translocation includes wild-type alleles of both lethal loci so that the females are viable. Matings between males of the BL-2 strain and normal females of the wild-type strain gave 99.74% male progeny. Exceptional females were due to recombination between the sl-2 and sl-15 loci. Thus, males of the BL-2 strain have a potential to suppress wild populations of the pest. Another envisaged use of this method is for an effective sexing technique.     

Repeated losses of TTAGG telomere repeats in evolution of beetles (Coleoptera)

We studied the occurrence of (TTAGG) _n telomere repeats in 12 species of beetles, representing main lineages of the Coleoptera phylogenetic tree, by Southern hybridization and fluorescence in situ hybridization (FISH). In contrast to other insect orders, beetles were heterogeneous with respect to the occurrence of TTAGG repeats. In addition, the presence or absence of (TTAGG) _n motif was irrespective of phylogenetic relationships. In the suborder Polyphaga, six species displayed positive hybridization signals. These were Silpha obscura, Agrilus viridis, Ampedus sanguineus, Stegobium paniceum, Oryzaephilus surinamensis, and Leptinotarsa decemlineata. Whereas negative signals were obtained in three polyphagan species, Geotrupes stercorarius, Thanasimus formicarius, and Sitophilus granarius. In the suborder Adephaga, the TTAGG sequence was present in one species, Graphoderus cinereus, and absent in two species, Orectochilus villosus and Pterostichus oblongopunctatus. We concluded that the telomerase-dependent (TTAGG) _n motif had been repeatedly lost in different phylogenetic branches of Coleoptera and probably replaced with another mechanism of telomere elongation. This had to happen at least 5–6 times. The results suggest a predisposition or a backup mechanism of telomere maintenance in the genome of beetles that enabled them to make frequent evolutionary changes in the telomere composition.     

Cytogenetic Characterization and AFLP-Based Genetic Linkage Mapping for the Butterfly Bicyclus anynana,Covering All 28 Karyotyped Chromosomes

Background

The chromosome characteristics of the butterfly Bicyclus anynana, have received little attention, despite the scientific importance of this species. This study presents the characterization of chromosomes in this species by means of cytogenetic analysis and linkage mapping.

Methodology/Principal Findings

Physical genomic features in the butterfly B. anynana were examined by karyotype analysis and construction of a linkage map. Lepidoptera possess a female heterogametic W-Z sex chromosome system. The WZ-bivalent in pachytene oocytes of B. anynana consists of an abnormally small, heterochromatic W-chromosome with the Z-chromosome wrapped around it. Accordingly, the W-body in interphase nuclei is much smaller than usual in Lepidoptera. This suggests an intermediate stage in the process of secondary loss of the W-chromosome to a ZZ/Z sex determination system. Two nucleoli are present in the pachytene stage associated with an autosome and the WZ-bivalent respectively. Chromosome counts confirmed a haploid number of n = 28. Linkage mapping had to take account of absence of crossing-over in females, and of our use of a full-sib crossing design. We developed a new method to determine and exclude the non-recombinant uninformative female inherited component in offspring. The linkage map was constructed using a novel approach that uses exclusively JOINMAP-software for Lepidoptera linkage mapping. This approach simplifies the mapping procedure, avoids over-estimation of mapping distance and increases the reliability of relative marker positions. A total of 347 AFLP markers, 9 microsatellites and one single-copy nuclear gene covered all 28 chromosomes, with a mapping distance of 1354 cM. Conserved synteny of Tpi on the Z-chromosome in Lepidoptera was confirmed for B. anynana. The results are discussed in relation to other mapping studies in Lepidoptera.

Conclusions/Significance

This study adds to the knowledge of chromosome structure and evolution of an intensively studied organism. On a broader scale it provides an insight in Lepidoptera sex chromosome evolution and it proposes a simpler and more reliable method of linkage mapping than used for Lepidoptera to date.     

The Effect of Male Mating Competitiveness, Developmental Rate, and Viability of Larvae and Pupae in Drosophila melanogaster Heterozygous for the Temperature-Sensitive Lethal Mutation l(2)M167DTS on the Dynamics of the Mutation Elimination from the Population

The dependence of selection on an introduced mutation l(2)M167 ^DTS on male mating competitiveness, viability, and developmental rate of larvae and pupae of Drosophila melanogaster, heterozygous for this mutation, was examined in population experiments with preset conditions. The limitations of fitness parameters of individuals l(2)M167 ^DTS /+ relative to individuals +/+ were estimated according to the conditions of the experiment and phenotypic characteristics of the mutation studied. Under conditions of limited food supply and dependence on emergence time in each generation, the sequence of female mating was shown to be of less importance than the order of medium utilization by the progeny of a certain genotype related to the male success in the first mating. The limiting factors acting on the l(2)M167 ^DTS mutation were viability and developmental rate.__________Translated from Genetika, Vol. 41, No. 5, 2005, pp. 620–625.Original Russian Text Copyright © 2005 by Kulikov, Marec, Mitrofanov.     

High recombinagenic activities of three antiviral agents, adenine derivatives, in the Drosophila wing spot test

Three adenine derivatives (R,S)-9-(2,3-dihydroxypropyl)adenin (DHPA), D-eritadine (EA), and 9-(2-phosphonylmethoxyethyl)adenine (PMEA), prospective antiviral drugs, were subjected to genotoxicity analysis using the somatic mutation and recombinatino test in Drosophila melanogaster. All three compounds were found to be very potent inducers of mosaic spots on Drosophila wings in a dose-related fashion. Data obtained in inversion-free flies revealed that the compounds, in particualr DHPA and EA (nucleoside analogues), are highly effective in the induction of mitotic recombination. PMEA, a nucleotide, exhibited a rather different genotoxic profile from those of DHPA and EA, indicating a different mechanism of genetic action of this compound. Of somatic mutations, chromosome aberrations, rather than point mutations seem to play a major role in the genotoxicity of PMEA. In flies carrying an inversion chromosome, which eliminates most products of mitotic recombination, reduced spot frequencies were obtained, which, however, were still unexpectedly high for compounds with strong recombinagenic activities. Most probably, in additino to structural mutations of chromosomes, double mitotic crossing-over and non-reciprocal recombinatino events similar to unequal sister-strand recombination of gene conversion significantly contributed to spot induction in the inversion heterozygous flies. Concerning the mechanism of genotoxic action, we suggest that these adenine derivatives can be incorporated into DNa chains during replication. This would result, via breaks and DNa repair mechanisms, either in various recombination events or in chromosome aberrations.     

Severe urinary tract malformation in the course of a twin pregnancy. Apropos of its management

What do we do when one of two monozygotic twins is affected with a severe urinary malformation? - termination of the affected zygote? - termination of the two zygotes as wanted by the parents? - not any intervention? About a personal case, the authors described their experience.     

Recessive microencephaly linked to the X chromosome

A family with X-linked recessive microcephaly is reported. As patients there were found 8 men or boys respectively out of 3 generations, all of them being related by their mentally healthy mothers. Besides microcephaly the patients showed growth retardation and obesity. Some of them, in addition, had various anomalies as inguinal or umbilical hernias, cryptorchism, tapering fingers, contractures, deeply rooted thumbs and club-feet. There were no hints for a metabolic defect or a chromosomal aberration. The dermatoglyphics could be investigated in 5 patients and showed in all of them a shifting of the axial triradius into the distal position t'. Comparing the own findings with case reports on X-linked microcephalies, the above mentioned family was found not to correspond to any of these observations. It is assumed that in this family, a new disease has occurred which until now has not yet been described, so that the X-linked microcephalies seem to be a heterogenous group of disease from the genetic point of view.