Marko Andjelkovic

Antimutagenic effect of sage tea in the wing spot test of Drosophila melanogaster

The present study assayed the antimutagenic potential of Salvia officinalis (sage) in the form of tea infusion, by the somatic mutation and recombination test (SMART) on Drosophila melanogaster. The use of herbal infusions is much common in the human diet, so the aim of the present study was to estimate the antimutagenic effects of the S. officinalis tea rather than essential oils. Methyl methanesulphonate (MMS) was used as the mutagen and positive control. Several types of treatment were performed: short acute treatment with sage infusion or MMS, longer (chronic) treatment with sage solution or MMS, and two combined treatments, i.e. short treatment with sage followed by a longer treatment with MMS and vice versa. Sage infusion used in our experiments showed a clear antimutagenic effect, reducing the frequency of mutations induced by MMS. The inhibition effect of sage tea is obtained and confirmed when pre- or post-treatments with mutagen were used. The results indicate that although sage in this regime decreases the number of mutation events, it is not efficient enough in case of the 2 h sage pre-treatment. Antioxidant activity, suppression of metabolic activation, could be mechanisms through which sage or some of its components act as desmutagen.

A genetic correlation between the sexes for mating speed in Drosophila melanogaster

Abstract The aim of this study was to test for a genetic correlation for mating speed between male and female Drosophila melanogaster . Males and females were selected separately for high and low mating speed, and each selection regime was replicated three times. Analysis of the direct response to selection in each generation showed a significant effect in females only. A full assay of the mating speed of males and females of all selected lines and of two samples of the base stock was made in generation 9. This showed a significant direct response to selection in both sexes, largely attributable to evolution in the ‘slow’ lines. There was also a significant correlated response, with males of the ‘fast’ female lines and females of the ‘fast’ male lines showing faster mating speeds than their counterparts from the ‘slow’ lines. It is not known if selection favours different mating speeds in the two sexes, but the genetic correlation between them would constrain independent evolution of male and female behaviour.

Adaptive significance of amylase polymorphism in Drosophila. VI. Properties of two amylase variants and the effect of food components on amylase activity in Drosophila subobscura

1. Properties of amylase from two D. subobscura strains homozygous for two different amylase variants (AmyS and AmyF) were determined. 2. Amylase of both strain adults showed a pH optimum of 7.8. 3. The AmyF enzyme showed a higher thermostability. 4. They differed in both maximum activity and Michaelis constant (Vmax of 6.25 and 3.45, Km of 0.7% and 0.42% starch for AmyS and AmyF, respectively). 5. The effect of different feeding conditions in amylase activity in the above Drosophila strains was also studied. Amylase activity was always detected but to a different level depending on diet composition.

Adaptive significance of amylase polymorphism in Drosophila IV. A comparative study of biochemical properties of the alpha-amylase in DrosophilaMelanogaster, D. hydei, D. subobscura, and D. busckii

Abstract 1. 1. The α-amylase of four species of Drosophila was characterised by several biochemical parameters. 2. 2. It was found that they differed in pH optima, temperature optima, Michaelis constants and maximal activities as well. 3. 3. Variability of α-amylase on the biochemical level in the species of Drosophila which we have studied suggests at least their ability to differentially exploit food resources in heterogeneous environments.

THE EFFECT OF LEAD ON FITNESS COMPONENTS AND DEVELOPMENTAL STABILITY IN DROSOPHILA SUBOBSCURA

We analyzed the developmental time, egg-to-adult viability, and developmental stability (fluctuating wing size asymmetry) in Drosophila subobscura, maintained for six generations on different concentrations of lead. Development time is significantly affected by generation and lead concentration, but interaction of these factors is not a significant source of variability for this fitness component. Generation and the interaction generation x concentration of lead significantly affect egg-to-adult viability. Levenes test of heterogeneity of variance showed that variability of FA is not significant in any of the samples. Within both lead concentrations females showed significantly higher FA indices for the wing width than males. Within sexes, a significantly higher FA was found only in females for wing width FA between the control and the lower concentration of lead. The results show that if strong relationship between FA and the studied fitness components exists, it results in a stronger selection of unstable genotypes under lead as a stress factor and, consequently, FA needs to be used with caution as a biomarker in natural populations under environmental stress.

Outbreeding causes developmental instability in Drosophila subobscura

A possible effect of interpopulation hybridization is either outbreeding depression, as a consequence of breakdown of coadapted gene complexes which can increase developmental instability (DI) of the traits, or increased heterozygosity, which can reduce DI. One of the principal methods commonly used to estimate DI is the variability of fluctuating asymmetry (FA). We analysed the effect of interpopulation hybridization in Drosophila subobscura through the variability in the wing size and the FA of wing length and width for both sexes in parental, F1 and F2 generations. The results of the wing size per se in intra- and interpopulation hybrids of D. subobscura do not explicitly reveal the significance of either of the two hypotheses. However, the results of the FA of the wing traits give a different insight. The FA of wing length and width generally increases in interpopulation crosses in F1 with respect to the FA in the parental generation, which suggests the possibility that outbreeding depression occurred in the first generation after the hybridization event. We generally observed that the FA values for the wing length and width of interpopulation hybrids were higher in F1 and F2 generations, compared to intrapopulation hybrids in same generations. These results suggest that the association between coadaptive genes with the same evolutionary history are the most probable mechanism that maintains the developmental homeostasis in Drosophila subobscura populations.

In vitro cytogenetic analysis of the effects of oxytocin on human peripheral blood lymphocytes.

The purpose of this study was to determine possible genotoxic and cytotoxic (or mitogenic) effects of high concentrations of oxytocin, active component of Syntocinon in cultures of human peripheral blood lymphocytes. Two test systems were used: (1) analysis of numerical and structural chromosome aberrations, and (2) the in vitro sister chromatid exchange (SCE) test. On the basis of the results obtained it can be concluded that oxytocin does not express any genotoxical properties. Furthermore, the mitotic index did not change significantly.

Frequency dependent selection: I. Rare male phenomenon in D. subobscura dependent on the proportion of Amy genotypes and substrate composition

Analysis of the rare male mating advantage in D. subobscura, as a type of frequency dependent selection on maltose and starch media, was done by applying different statistical approaches (χ2, cross‐product ratio, variance and regression analysis). They reveal that mating occurs at random when proportions of prospective mates are equal, and that mating success of the males homozygous for Amy‐locus genotypes (S/S and F/F) depends on their proportion. Regression analysis showed that the F/F males are sexually more active (have higher vigour) than S/S males. Rare male effect is one‐sided and appears in F/F males that partake in more heterogamic matings. Comparison of the number of observed and expected homo‐ and heterogamic matings shows that homogamic matings are more frequent. Multifactorial analysis of variance shows that the number of matings are different for nine pairs of lines and four possible mating types (SfSm, SfFm, FfSm, FfFm). The rare male phenomenon is not dependent on different food composition, but is associated with variations in individual genotypes.

Adaptive significance of amylase polymorphism in Drosophila. I: The geographical pattern of allozyme polymorphism at the amylase locus in Drosophila subobscura

Allelic variation at the Amy locus was studied in eight natural populations from the central and northern range of D. subobscura, and the geographical pattern of Amy polymorphism over the range of this species was described. Even though regional and local differences in gene frequencies were found, in general the same alleles occur at high, intermediate and low frequencies, in nearly all populations. There are no significant differences in allele frequencies, but there is significant difference in the degree of heterozygosity among groups of populations from the northern, central and southern range. An analysis of population subdivision indicates that heterogeneity within populations is higher than between populations. Genetic distance values indicate that there is a variable degree of geographical differentiation between local populations. Variability within and between continental and insular populations is also discussed.

Variation in skull size and shape of two snake species (Natrix natrix and Natrix tessellata)

We examined morphological differences in cranium size and shape between closely related snake species, Natrix natrix and Natrix tessellata (Natricinae, Colubroidea), as well as variation within species. These two snake species have similar ecology and habitat preferences but differ in feeding strategies. Our hypothesis was that divergence in size and shape of cranial elements between species depends on their functional role and anatomical relationships. To analyse complex, kinetic crania, we applied computed microtomography and 3D geometric morphometrics. We analysed size and shape of six cranial elements separately. We selected two “non-trophic” structures (akinetic braincase and mobile nasals) and four movable “trophic” skeletal elements (maxillae, quadrates, pterygoids and compound bones) which are involved in prey capture and swallowing. Our results showed that N. natrix and N. tessellata significantly differ in size and shape of all analysed cranial elements. In both species, cranium is significantly larger in females than in males. To account for possible differences in shape due to differences in size, we estimated allometric and non-allometric component of shape variation. For all elements, except nasals, allometry accounted for a significant proportion of the variance in shape. The analysis of non-allometric component of shape variation revealed significant dimorphism in shape of the braincase and maxilla between N. tessellata females and males, and marginally significant sexual dimorphism in shape of maxilla in N. natrix. These results indicated that sexual dimorphism in skull shape is species specific and not entirely caused by selection for larger size in females.