Variation for resistance to aphids (Homoptera: Aphididae) among tomato inbred backcross lines derived from wild Lycopersicon species

Two tomato inbred backcross line (IBL) populations, derived from crosses between aphid-susceptible Lycopersicon esculentum Mill. 'Peto 95-43' X resistant wild L. pennellii Corr (D'arcy) accession LA716, and Peto 95-43 X resistant wild L. hirsutum f. glabratum Mull accession LA407, were evaluated in replicated field experiments for resistance to potato aphid, Macrosiphum euphorbiae (Thomas), and green peach aphid, Myzus persicae (Sulzer). Aphid infestation scores for each IBL and control (LA716, LA407, Peto 95-43, and susceptible 'Alta') plot were recorded weekly for 5 and 9 wk during the summers of 2000 and 2001, respectively. Aphid infestation scores from leaflets were used to calculate area under the infestation pressure curve (AUIPC), a measure of aphid infestation throughout the growing season, for each IBL and control. Score AUIPC was highly correlated with actual aphid count AUIPC, indicating that scores accurately reflected aphid infestation. Score AUIPC was also highly correlated across both years (2000 and 2001) and locations. Low score AUIPC was significantly correlated with larger plant size and sprawling, indeterminate plant growth habit. Seven IBLs, LA716, and LA407 were significantly more resistant to aphids (lower score AUIPC) than susceptible parent Peto 95-43 in both years. Two IBLs, 1034 and 1051, were not significantly different from resistant LA407 for score AUIPC in both years. The seven aphid-resistant IBLs identified here can be useful as donor parent material for resistance breeding efforts in cultivated tomato.     

Importance de l'étude de la répartition écologique pour la taxonomie des éponges calcaires

Résumé 1. Les travaux deSarà (1953) et deBurton (1963) ont remis en question la valeur systématique des caractères morphologiques dans la classification des Eponges Calcaires, et ont proposé de considérer de nombreuses formes connues comme des variétés individuelles et régionales d'espèces très plastiques et variables. Nous avons essayé de préciser, par l'observation directe en plongée libre, la distribution et les préférences écologiques des Calcaires, de définir ainsi les limites naturelles de leurs populations, et d'étudier ensuite la variabilité des caractères morphologiques à l'intérieur de ces populations.2. Nous exposons ici l'exemple des espèces des genresClathrina etAscandra, étudiées en Adriatique, dans les régions de Marseille et de Roscoff. Leur distribution est en rapport direct et très précis avec l'exposition aux vagues et à la lumière, à tel point que sur une surface réduite plusieurs espèces se succèdent et se remplacent en fonction de l'exposition de l'endroit. Dans la règion de Roscoff cette distribution est plus large ce qui est dû aux effets des marées, mais les zones écologique préférentielles pour les espèces deClathrina ont pu être établies en fonction de l'importance de l'apport des sédiments par les eaux côtières.3. La possibilité de définir des populations dont la distribution est très précisemment délimitée malgré une coexistence dans un espace réduit, et qui ne sont pas réliées par les formes transitoires, permet d'éliminer l'hypothèse de la cospécificité de ces populations. Elle permet également d'établir les variations morphologiques possibles au sein d'une espèce, de retenir les caractères significatifs pour la classification, et finalement de distinguer les espèces qui se ressemblent morphologiquement. Dans le cas d'animaux qui, commeClathrina, possèdent très peu de caractères utilisables en systématique, c'est la seule façon de résoudre les problèmes de leur taxonomie.

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The importance of research on the ecological distribution for the taxonomy of calcareous sponges

The particular difficulties of the taxonomy of calcareous sponges are due to their great plasticity and their capacity for adaptation which obscure the natural limits of species. An attempt was made to define the natural populations of the Mediterranean species of the generaClathrina andAscandra through a study of their ecological distributions. The populations not connected by the transitory forms were defined by their ecological preferences, and, as they are found in a close cohabitation, were treated as having the specific values. The variability of different morphological features is discussed, the features significant for taxonomy are pointed out and the morphologically close species are defined.

     

Phylogeny and biogeography of the alpine newt Mesotriton alpestris (Salamandridae, Caudata), inferred from mtDNA sequences

In this paper, we performed phylogenetic analyses of Mesotriton alpestris populations from the entire range of species distribution, using fragments of two mtDNA genes, cytochrome b (309bp) and 16S rRNA ( approximately 500bp). Sequence diversity patterns and phylogenetic analyses reveal the existence of a relict lineage (Clade A) of late Miocene origin, comprising populations from south-eastern Serbia. This lineage is proposed to be ancestor to a western and an eastern lineage, which diverged during the middle Pliocene. The western lineage is further divided in two clades (Clades B, C) of middle Pliocene origin that represent populations from Italy (B) and populations from central Europe and Iberia (C). Further subdivision, dated back to the middle-late Pliocene, was found within the eastern lineage, representing southern (Clade D) and central-northern (Clade E) Balkan populations, respectively. Extensive sequence divergence, implying greater isolation in multiple refugia, is found within eastern clades, while the western clades seem to have been involved in the colonization of central, western and north-eastern Europe from a hypothetical refugium in central Europe. The extent of divergence does not support the current taxonomy indicating cryptic speciation in the Balkans, while paedomorphic lineages were found to have been evolved during early-middle Pleistocene probably as a response to the ongoing dramatic climatic oscillations.     

A study on the genotoxic effects of 8-Cl-cAMP on human lymphocytes in vitro

8-chloro-cyclic adenosine 3',5'-monophosphate (8-Cl-cAMP) is the most potent cAMP analogue that selectively inhibits a variety of cancer cell lines in vitro and tumors in vivo. Its action toward a variety of tumors, especially when coupled with other antitumor agents, have lead to phase I clinical investigations and recently phase II clinical investigations. Until today very little was done to evaluate its genotoxic potential. In order to evaluate its genotoxic potential we used the cytogenetic and cytokinesis block micronucleus assay in vitro on peripheral blood lymphocytes of healthy individuals. Using three concentrations (1 microM, 5 microM and 15 microM), 8-Cl-cAMP in normal human peripheral blood lymphocytes did not induce any cytogenetic aberrations of the structural type [chromatid breakage, isochromatid breakage and gaps], but did induce premature centromere separation (PCS) in all respective doses and increased the frequency of micronuclei (p <0.05) only in the highest dose (15 microM). Antiproliferative action of 8-Cl-cAMP was estimated by using the cytokinesis block nuclear division index (NDI). The results showed a decrease in the NDI of cells exposed to all doses of 8-Cl-cAMP when compared to control. Therefore, the overall results show a genotoxic potential of 8-Cl-cAMP in peripheral blood lymphocytes in vitro.     

Osteometric dimensions of metacarpal bones with respect to the professional exposure to vibration

The comparative analysis of the osteometric dimensions of metacarpal bones in three groups of males (aged from 23 to 63 years) differing with respect to the presence of the professionally connected long-term exposure to the vibration is performed. The sample encompasses forest workers employed in wood industry (exposed to heavy physical work and to the daily use of hand-held vibrating tools) from two regions of Croatia: Podravina (n = 192) and Gorski Kotar (n = 115). The control group is formed using the random sample (selected according to age criterion) of phenotypically healthy male inhabitants of rural communities of Eastern Adriatic islands and peninsula (n = 200). Additionally, the influence of the level of calcium in diet, as a regional nutritional characteristic of particular regions of Croatia, is also considered. The regression of the percent cortical area (PCA) of the second left metacarpal bone and age showed that significant decrease of PCA in older age can be observed only in males from Eastern Adriatic (the control group), while that is not so in either group of males professionally exposed to vibration. Authors conclude that the analysis of the osteometric dimensions performed on males professionally daily exposed to vibration missed to provide evidence to support the hypothesis of long-term exposure to vibration as a risk for accelerated osteoporosis of metacarpal bones.     

Development of interstitial cells of Cajal in the human digestive tract as the result of reciprocal induction of mesenchymal and neural crest cells

Neural crest cells (NCC) can migrate into different parts of the body and express their strong inductive potential. In addition, they are multipotent and are able to differentiate into various cell types with diverse functions. In the primitive gut, NCC induce differentiation of muscular structures and interstitial cells of Cajal (ICC), and they themselves differentiate into the elements of the enteric nervous system (ENS), neurons and glial cells. ICC develop by way of mesenchymal cell differentiation in the outer parts of the primitive gut wall around the myenteric plexus (MP) ganglia, with the exception of colon, where they appear simultaneously also at the submucosal border of the circular muscular layer around the submucosal plexus (SMP) ganglia. However, in a complex process of reciprocal induction of NCC and local mesenchyma, c‐kit positive precursors are the first to differentiate, representing probably the common precursors of ICC and smooth muscle cells (SMC). C‐kit positive precursors could represent a key impact factor regarding the final differentiation of NCC into neurons and glial cells with neurons subsequently excreting stem cell factor (SCF) and other signalling molecules. Under the impact of SCF, a portion of c‐kit positive precursors lying immediately around the ganglia differentiate into ICC, while the rest differentiate into SMC.     

Comparative research on substance abuse and self-perception among adolescents with physical handicap

The research on substance (alcohol, tobacco and drug) abuse and on self-perception was done by comparing a test group of physically disabled adolescents and a test group of non-disabled adolescents. The respondents of the experimental group were students of the only special high school for physically handicapped persons in Croatia, Zagreb. The respondents of the control group were the students of two regular high schools in the capital of Croatia. The instrument used in this research was a self-reported, anonymous questionnaire. The respondents completed the questionnaire in the classroom. The data analysis regarding alcohol abuse indicated that physically disabled adolescents drink more often and out of quite different motives than their non-disabled peers. Regarding the prevalence, frequency, quantity and motives for smoking, no statistically significant difference has been found between the tested groups. On the contrary, significant differences between handicapped and non-disabled adolescents were evident regarding drug abuse. Only one physically disabled examinee used a drug--marijuana, only a few times a year. On the other hand, almost one quarter of the non-disabled adolescents use at least one, five at the most, type of drug sometimes or often. The results on the self-perception scale show that adolescent with physical disabilities have a much more negative attitude toward themselves than non-disabled controls. Their self-esteem and self-confidence are seriously diminished. Described findings could have a mighty impact on ways of preventing substance abuse, and on ways of increasing self-esteem among disabled and non-disabled adolescents.     

Compartmentalization of the splicing machinery in plant cell nuclei

The cell nucleus is a membrane-surrounded organelle that contains numerous compartments in addition to chromatin. Compartmentalization of the nucleus is now accepted as an important feature for the organization of nuclear processes and for gene expression. Recent studies on nuclear organization of splicing factors in plant cells provide insights into the compartmentalization of the plant cell nuclei and conservation of nuclear compartments between plants and metazoans.     

Expression of one sponge Iroquois homeobox gene in primmorphs from Suberites domuncula during canal formation

Sponges (Porifera) represent the evolutionary oldest multicellular animals. They are provided with the basic molecules involved in cell-cell and cell-matrix interactions. We report here the isolation and characterization of a complementary DNA from the sponge Suberites domuncula coding for the sponge homeobox gene, SUBDOIRX-a. The deduced polypeptide with a predicted Mr of 44,375 possesses the highly conserved Iroquois-homeodomain. We applied in situ hybridization to localize Iroquois in the sponge. The expression of this gene is highest in cells adjacent to the canals of the sponge in the medulla region. To study the expression of Iroquois during development, the in vitro primmorph system from S. domuncula was used. During the formation of these three-dimensional aggregates composed of proliferating cells, the expression of Iroquois depends on ferric iron and water current. An increased expression in response to water current is paralleled with the formation of canal-like pores in the primmorphs. It is suggested that Iroquois expression is involved in the formation of the aquiferous system, the canals in sponges and the canal-like structures in primmorphs.