Browsing by Author "Khadem, Mahnaz"
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- Effects of nonthermal atmospheric-pressure plasma on Drosophila developmentPublication . Ferreira, Margarida I.; Gomes, José Gabriel Lira; Benilov, Mikhail S.; Khadem, MahnazNonthermal atmospheric-pressure plasma (NTAPP) is known to induce a wide range of responses at the cellular level. This study is concerned with the effects of NTAPP on a eukaryotic organism as a whole: Drosophila melanogaster. Exposure influenced the larval viability and caused an array of traits that can be classified into three major groups: (1) phenotypic anomalies in larvae (such as melanotic masses, melanized and broken trachea, incomplete shedding of the old cuticle during molting), morphological anomalies of pupae (small size, abnormal form, aberrant development, cryptocephalic forms), and developmental anomalies in adults (abnormal formation of wing, legs, and thorax); (2) larval behavior alteration (nonfeeding of first and second instar larvae, premature wandering, running away from food, immature pupae formation); and (3) excessive fat accumulation and lipid oxidation. The majority of the observed traits can be linked to molting and metamorphosis controlled by the endocrine system, in particular with the steroid hormone ecdysone. Results support the hypothesis that the interaction of NTAPP with the membranes of various organs can have a major role in the interruption of normal ecdysogenesis.
- Endohelminth parasites of the blacktail comber Serranus atricauda (Pisces: Serranidae), from Madeira Archipelago (Atlantic Ocean)Publication . Costa, Graça; Khadem, Mahnaz; Silva, Sofia; Moreira, Egberto Melo; D’Amélio, StefanoFour different endohelminth parasite taxa were found in the viscera of the blacktail comber Serranus atricauda Günther, 1874 caught in the Madeira Archipelago. Nematodes were the dominant group, represented by 2 different taxa, Hysterothylacium spp. Ward & Magath, 1917 and Procamallanus (Spirocamallanus) halitrophus Fusco & Overstreet, 1978 comb. n. Plerocerci of the trypanorhynch Pseudogrillotia epinepheli (synonym: Grillotia epinepheli) Scholz, Garippa & Scala, 1993, and cystacanths of the acanthocephalan Bolbosoma vasculosum Rudolphi, 1819 were found in the visceral cavity. New host records for P. (S.) halitrophus and P. epinepheli and the extension of the geographic distribution of these 2 parasite species provide evidence of parasite transference between the Madeira Archipelago, the Mediterranean and the Gulf of Mexico. The paucity of the parasite fauna of blacktail comber reflect a combination of fish host selective feed ing on particular dietary items and its territorial behaviour.
- Genetic exchange versus genetic differentiation in a medium-sized inversion of Drosophila: the A2/AST arrangements of Drosophila subobscuraPublication . Nóbrega, Clévio; Khadem, Mahnaz; Aguade, Montserrat; Segarra, CarmenChromosomal inversion polymorphism affects nucleotide variation at loci associated with inversions. In Drosophila subobscura, a species with a rich chromosomal inversion polymorphism and the largest recombinational map so far reported in the Drosophila genus, extensive genetic structure of nucleotide variation was detected in the segment affected by the O3 inversion, a moderately sized inversion at Muller’s element E. Indeed, a strong genetic differentiation all over O3 and no evidence of a higher genetic exchange in the center of the inversion than at breakpoints were detected. In order to ascertain, whether other polymorphic and differently sized inversions of D. subobscura also exhibited a strong genetic structure, nucleotide variation in 5 gene regions (P236, P275, P150, Sxl, and P125) located along the A2 inversion was analyzed in Ast and A2 chromosomes of D. subobscura. A2 is a medium-sized inversion at Muller’s element A and forms a single inversion loop in heterokaryotypes. The lower level of variation in A2 relative to Ast and the significant excess of low-frequency variants at polymorphic sites indicate that nucleotide variation at A2 is not at mutation–drift equilibrium. The closest region to an inversion breakpoint, P236, exhibits the highest level of genetic differentiation (FST) and of linkage disequilibrium (LD) between arrangements and variants at nucleotide polymorphic sites. The remaining 4 regions show a higher level of genetic exchange between A2 and Ast chromosomes than P236, as revealed by FST and LD estimates. However, significant genetic differentiation between the Ast and A2 arrangements was detected not only at P236 but also in the other 4 regions separated from the nearest breakpoint by 1.2–2.9 Mb. Therefore, the extent of genetic exchange between arrangements has not been high enough to homogenize nucleotide variation in the center of the A2 inversion. A2 can be considered a typical successful inversion of D. subobscura according to its relative length. Chromosomal inversion polymorphism of D. subobscura might thus cause the genome of this species to be highly structured and to harbor different gene pools that might contribute to maintain adaptations to particular environments.
- Global warming and chromosomal inversion adaptation in isolated islands: Drosophila subobscura populations from MadeiraPublication . Madrenas, Raquel; Balanyà, Joan; Arenas, Concepció; Khadem, Mahnaz; Mestres, FrancescGlobal warming is an environmental phenomenon to which species must adapt to survive. Drosophila sub obscura presents an adaptive capacity due to its chromosomal inversion polymorphism. Until now, the impact of global warming on this polymorphism has been studied in D. subobscura populations located either on a continental mainland or on islands not far from a continent. In this context, gene flow could be a relevant mechanism allowing the movement of thermally adapted inversions between populations. Our aim was to sample and study the chromosomal polymorphism on Madeira, a small isolated island in the Atlantic Ocean. We compared our findings with those reported in the same location approximately four and five decades ago. Moreover, we studied whether global warming has occurred on this island by analyz ing mean, maximum and minimum temperatures over a 55-year period. All atmospheric parameters have increased significantly, consistent with climate change expectations. Frequencies and chromosomal thermal index values of thermal adapted inversions remained quite stable over years. Furthermore, J, U and O chro mosomes are almost fixed for “warm” adapted inversions. Thus, if there is little genetic variability remaining and temperatures continue increasing, island populations of D. subobscura might be on the threshold of endangerment. However, apart from selection, genetic drift and inbreeding, other processes, such as phenotypic plasticity or thermoregulatory behavior, could be involved in the survival of the species’ populations. Finally, although in danger, D. subobscura is a generalist that lives in humanized environ ments, and this fact could favor its persistence on Madeira Island.
- Helminth parasites of the Atlantic chub mackerel, Scomber colias Gmelin, 1789 from Canary Islands, Central North Atlantic, with comments on their relations with other Atlantic regionsPublication . Costa, Graça; Cavallero, Serena; D’Amélio, Stefano; Paggi, Lia; Santamaria, Maria; Perera, Clara; Santos, Maria; Khadem, MahnazEleven parasite taxa were found infecting 68 Atlantic chub mackerel, Scomber colias Gmelin, 1789 from the Canary Islands, Central North Atlantic. The most abundant parasites were the gill monogenean Pseudokuhnia minor (P = 54.4%), larval anisakid nematodes (P = 11.8%) in the body cavity, a larval tetraphyllidean infecting bile ducts (P = 8.8%) and didymozoid digeneans infecting the gills (P = 7.4%). No correlation between fish length and abundance of infection with these parasites was found. Within the Atlantic, the comparison of present results with previous reports on the occurrence of parasites in this fish host, might suggest that there is more than one population unit of Atlantic chub mackerel in the Eastern Atlantic
- Lack of congruence between morphometric evolution and genetic differentiation suggests a recent dispersal and local habitat adaptation of the Madeiran lizard Lacerta dugesiiPublication . Brehm, António; Khadem, Mahnaz; Jesus, José; Andrade, Paula; Vicente, LuísGenetic differentiation among nine populations of the endemic lizard Lacerta dugesii Milne-Edwards 1829 (Lacertidae) from four groups of islands constituting the Archipelago of Madeira, was investigated by protein electrophoresis at 23 enzyme loci. Among twenty polymorphic loci, the total genetic diversity was due primarily to intra-population variation. The allele and genotypic frequencies among populations showed some heterogeneity, allowing the species to present a structuring pattern compatible with their geographical clustering. Some evidence suggests that selection acting on some loci in different ecological conditions may be responsible for the clustering of the populations studied. There was no apparent isolation effect expected under an "island" model of population divergence, and no correlation was found between genetic and geographic distances among populations. Morphological variation of the proposed three L. dugesii subspecies is not congruent with the allozyme analysis. This most probably suggests a rapid colonization of the islands followed by a strong effect of selection operating over the morphological characters used to define the subspecies.
- Larval cestodes infecting the deep-water fish, Cataetyx laticeps (Pisces: Bythitidae) from Madeira Archipelago, Atlantic OceanPublication . Costa, Graça; Khadem, Mahnaz; Dellinger, Thomas; Biscoito, Manuel; Moreira, Egberto MeloParasites of deep-water fishes are less known in comparison to the parasites of fishes living in the demersal and epipelagic ocean zones. In the present research note we report the occurrence of larval trypanorhynch cestodes in a rare deep-water fish, the deep-water brotula, Cataetyx laticeps. Based on the 28S rDNA (region D1-D3) sequence homology and the phylogenetic analysis, the larval cestodes are putatively assigned to the genus Grillotia. It is suggested that the definitive host of this trypanorhynch is a batoid.
- Molecular identification and VOMs characterization of Saccharomyces cerevisiae strains isolated from Madeira region winery environmentsPublication . Castillo, Mariangie; Silva, Emanuel da; Câmara, José S.; Khadem, MahnazThe quality and typical characteristic of wines depends, among other factors, on the volatile organic metabolites (VOMs) that are biosynthesized by yeasts, mainly Saccharomyces cerevisiae species. The yeast strain influences the diversity and proportions of the VOMs produced during the fermentation process, as the genetic predisposition of the strains is a by-product of selective adaptation to the ecosystem. The present work reports the characterization of S. cerevisiae strains isolated from grape must, used in the Demarcated Region of Madeira (DRM) for winemaking. Yeast species were identified by amplification and by restriction fragment length polymorphism (RFLP) analysis of the region 5.8S-internal transcribed spacers (PCR-RFLP of 5.8S-ITS) of ribosomal DNA (rDNA). The strains identification was performed by analyzing the RFLP pattern of mitochondrial DNA (RFLP-mtDNA). The representative strains were selected for the characterization of the volatile profile through headspace solid-phase microextraction (HS-SPME) followed by gas chromatography-mass spectrometry (GC-MS) analysis. A total of 77 VOMs were identified. Higher alcohols, esters, and fatty acids were the major chemical families representing 63%, 16%, and 9%, respectively, in strain A and 54%, 23%, and 15% in strain B. The results indicate the influence of the strain metabolism in the production of VOMs, many of which probably participate in the aroma of the corresponding wines.
- Studies en enzymes of paramecium caudatumPublication . Khadem, Mahnaz
- Studies of the species barrier between Drosophila madeirensis and Drosophila subobscura. II. Genetic analysis of developmental incompatibilities in hybridsPublication . Khadem, Mahnaz; Krimbas, Costas B.The genetic analysis of two abnormal Characters, extra sex combs and abnormal head shape in hybrids between Drosophila madeirensis and Drosophila subobscura, revealed a major effect of the X chromosome in both cases. Autosomes also play a role in determining these abnormalities, the E chromosome in case of extra sex combs, the E and 0 chromosomes in case of abnormal head shape. Autosomes do not cause the two abnormal characters, without interacting with the X chromosome.