Radioprotective effect of six chemicals against X-ray-induced genetic damage in D. melanogaster

In Drosophila melanogater six chemicals were tested for radioprotectiveeffect against X-ray-induced genetic damage such as sex-linked recessive lethals and autosomal translocations using Oster's ring-X chromosome stock. A 2-day brood pattern was followed to score the damage induced at different spermatogenic stages separately. In all cases the chemicals were injected before X-irradiation. 10-mM solution of reduced glutathione (GSH) provided statistically significant protection against sex-linked recessive lethals in all broods. In translocation tests this chemical reduced the frequency in all broods but the result is not statistically significant. Cysteamine (MEA) did not show any protective effect but the frequency of lethals was slightly reduced in the first and fourth broods. 2-Aminoethyl isothiuronium Br·HBr (AET) showed a statistically significant protective effect when the data of the replicate experiments were pooled. Negative results were obtained for 5-hydroxytryptamine (5-HT) in sex-linked lethal tests. Aminoethyl phosphorothioate (AEPT) reduced the frequencies of both sex-linked lethals and autosomal translocations in all broods consistently but the results are not statistically significant. In tests for both lethals and translocations the reduction was largest in the stages with highest radiosensitivity. N(3-Aminopropyl)aminoethyl phosphorothioate (3AP-AEPT) gave no protection.     

Physiological tolerance of Drosophila simulans to dark environment: A comparison with D. melanogaster

According to ecological and behavioural studies, Drosophila simulans is considered to be less tolerant of darkness than its sibling species D. melanogaster which is well adapted both behaviourally and physiologically to darkness. The relationships between physiological and behavioural adaptations have been analysed by studying the developmental and the reproductive capacities of D. simulans submitted to various light regimes (LL, LD 12:12, DD). This species has a lower reproductive capacity than D. melanogaster but failed to react to light treatment. In particular, D. simulans showed no effect of darkness on either fertilization or ovarian function. The lack of differences between D. melanogaster and D. simulans as regards their physiological capacities in relation to light regime suggests that the selective pressures of light may act at different levels of regulation.     

Quantitative and qualitative changes in carbohydrates associated with spring deacclimation in contrasting Hydrangea species

Cold deacclimation and associated changes in soluble carbohydrates and water status of two Hydrangea species differing in susceptibility to frost injuries was followed under natural conditions. In fully cold hardy plants of H. macrophylla stem freezing tolerance fluctuated in parallel with changes in air temperature, while in a seasonal perspective increased temperatures caused a sigmoid deacclimation pattern in both H. macrophylla and H. paniculata. Timing of deacclimation was approximately synchronized in the two species, but H. paniculata, the hardier species based on mid-winter hardiness, deacclimated faster than H. macrophylla, indicating that deacclimation kinetics were not correlated with mid-winter hardiness. In both species concentrations of soluble sugars decreased during deacclimation and were highly correlated with stem cold hardiness and air temperatures. This suggests that sugar hydrolysis may be an important temperature-driven mechanism of deacclimation in Hydrangea. Accumulation patterns of specific carbohydrates differed between the two species, suggesting that they utilize different strategies to overcome cold. In H. paniculata, deacclimation was associated with an increase in stem water content, which occurred shortly before bud burst and hence may be a prerequisite for leafing out.     

High-frequency clicks of Hawaiian picture-winged Drosophila species

In this study, it is shown that the males of several picture-winged Drosophila subgroup species produced high-frequency clicking sounds when courting females. At the beginning of the courtship, the males may semaphore or vibrate their wings with a large amplitude, producing no audible sounds. After these ‘preliminary’ wing vibrations the males set their wings backwards in a normal resting position and vibrate them with a small amplitude, producing loud clicking sounds (up to 15000 cps), which differ from all Drosophila sounds described so far in both their spectral and their temporal structure. When producing these sounds the males always touch the abdomen of the female with their front legs, which might help the females receive the sounds as vibrational signals.     

Host use and developmental instability in the cactophilic sibling species Drosophila gouveai and D. antonietae

The Drosophila repleta group encompasses an ensemble of species that inhabit desertic areas that are inhospitable to other drosophilids. These species have a tractable ecology, as they breed and feed on necrotic tissues of a wide diversity of species of Cactaceae, with a certain degree of host specificity, which makes them suitable models to investigate the role of host plant shifts in diversification. Most species have their own primary host plant, which may be shared with a closely related species. However, the consequences of host plant shifts from primary to secondary hosts have not been thoroughly studied so far. We investigated the effects of the cactus host on developmental instability and performance of D. gouveai Tidon‐Sklorz & Sene and D. antonietae Tidon‐Sklorz & Sene (Diptera: Drosophilidae), a pair of closely related sibling species, and of their F1 interspecific hybrids reared in primary and secondary host plants. Fluctuating asymmetry (FA) for wing size was significantly greater in flies of both species reared in their respective secondary cactus host than in those grown in the primary host. Interspecific hybrids also exhibited host‐dependent levels of FA. However, hybrids did not show greater FA than the parental species, suggesting that hybridization per se did not affect developmental stability. Even though cactus host shifts affected different measures of fitness (larval viability and adult size) both in D. antonietae and D. gouveai, we did not detect a consistent relationship between FA and fitness. Our results suggest that FA cannot be used as a sensitive indicator of genetic and phenotypic quality and we discuss its application as a fitness predictor.     

Phloroglucinol derivatives in Dryopteris parallelogramma and D. patula

The phloroglucinol composition in two tropical American ferns, Dryoperis parallelogramma and D. patula has been investigated. Dryopteris parallelogramma, a member of the D. filix-mas complex, contains filixic acids, which are a characteristic of the group. Dryopteris patula contains aspidin, as do its relatives in the D. dilatata complex, and albaspidin-AA.     

The effect of reproductive activity on the longevity of male Drosophila melanogaster is not caused by an acceleration of ageing

Male D. melanogaster kept supplied with virgin females had lower longevity than males kept without access to females. Cessation of reproductive activity by males previously kept with females resulted after a short lag in the same life expectancy as that of flies of the same age which had never had females. Commencement of reproductive activity resulted in life expectancy indistinguishable from that of males of the same age kept with females throughout life. The effect of reproductive activity on longevity is therefore short-term and reversible and not due to an acceleration of ageing. This finding has implications for the way that different theories of the evolution of ageing should be tested.     

Host‐dependent phenotypic plasticity of aedeagus morphology in a pair of cactophilic sibling Drosophila species of the repleta group (Diptera,Drosophilidae)

The rapid evolution of male genital morphology is a characteristic feature of several animal groups. Such rapid divergence makes this trait a useful key for species identification. The aedeagus, the intromittent organ of male genitalia, is considered the main diagnostic trait in the Drosophila repleta group. In this study we analysed phenotypic plasticity and genetic variations associated with aedeagus size and shape in the cactophilic sibling species Drosophila gouveai Tidon‐Sklorz and Sene, 2001 and Drosophila antonietae Tidon‐Sklorz and Sene, 2001. Phenotypic plasticity in aedeagus morphology was evaluated in terms of the response to rearing media prepared with each species’ natural host plant, Pilosocereus machrisii Dawson, 1957 and Cereus hildmannianus Schum, 1890 respectively. Our results show that aedeagal shape differed significantly between species and that both shape and size presented host‐related phenotypic plasticity in both species. Flies reared on P. machrisii had, on average, larger aedeagi than those grown in C. hildmannianus. The general shape of aedeagus also differed significantly between flies that emerged in different host cactus. Patterns of variation in aedeagus morphology are discussed in the light of the current knowledge of evolutionary relationships and host plant use, in the D. buzzatii cluster, an assemblage of species in active cladogenesis.     

Wall loss and origin of soluble carbohydrates during mating of Chlamydomonas reinhardi

In the mating reaction between gametes of the green alga Chlamydomonas reinhardi, a lytic factor which solubilizes the cell wall is released. It has been shown that carbohydrates accumulate in the supernatant of mating gametes. We present here data which support the notion that the released carbohydrates arise from solubilized gametic cell walls. The evidence is based, in part, on the comparison of the carbohydrates and amino acids in the acid hydrolysates of cell-free supernatants to the reported composition of isolated cell walls. In both cases the three predominant sugars are mannose, arabinose and galactose, and also, in both cases, large amounts of the amino acid hydroxyproline are present. In addition, it is shown that if gametic cell walls are removed prior to mating interactions by treatment with a preparation of lytic factor, much less carbohydrate is subsequently released into the supematant, when such ‘nake’ gametes are mated.     

New yeast/E. coli/Drosophila triple shuttle vectors for efficient generation of Drosophila P element transformation constructs

We have generated a set of novel triple shuttle vectors that facilitate the construction of Drosophila-P-element transformations vectors. These YED-vectors allow the insertion of any kind of sequence at any chosen position due to the presence of a yeast casette which ensures replication and allows for homologous recombination in Saccharomyces cerevisiae. As a proof of principle we generated several reporter constructs and tested them in transgenic flies for expression and correct subcellular localization. YED-vectors can be used for many purposes including promoter analysis or the expression of tagged or truncated proteins. Thus, time-consuming conventional restriction site based multi-step cloning procedures can be circumvented by using the new YED-vectors. The new set of triple shuttle vectors will be highly beneficial for the rapid construction of complex Drosophila transformation plasmids.     

Sesquiterpenoid and acetylenic constituents of seven Clibadium species

The investigation of seven Clibadium species resulted in the isolation of a new germacrolide from C. surinamense, trans-β-bergamotene, a new sesquiterpene from C. asperum and a new C-17 acetylenic alcohol from C. glomeratum. Five known acetylenic compounds were present in some members of the genus. In good agreement with morphological data, the presence of ichthyothereol and its acetate in several members of Clibadium suggest affiliation with the genus Ichthyothere within the subtribe Milleriinae (Heliantheae-Compositae).     

Dynamics of extractable carbohydrates in Pisum sativum. III. The effect of IAA and temperature on content and translocation of carbohydrates in pea cuttings during rooting

The number of roots formed in cuttings of pea ( Pisum sativum L. cv. Alaska) was regulated both by the temperature and by IAA, whereas the time to the appearance of the first roots was regulated only by the temperature. Cuttings treated with 10^-3 M IAA had a smaller content of extractable carbohydrates than the control ones irrespective of the temperature. In the bases of cuttings rooted at 25°C the content of extractable carbohydrates was lower than in those rooted at 15°C. Cuttings treated with IAA showed up to elevenfold increase of extractable carbohydrates in the bases at day 3. This increase of soluble sugars was not correlated with the number of roots formed or the speed of rooting. It is concluded that IAA affects the accumulation of carbohydrates, and this is not connected with the rooting ability of the cuttings.     

Cardenolides in the latex and leaves of seven Asclepias species and Calotropis procera

The cardenolide content of the latex and leaves of seven Asclepias species and Calotropis procera was examined quantitatively by spectroassay a     

Genetically Derepressed Nucleoplasmic Stellate Protein in Spermatocytes of D. melanogaster Interacts with the Catalytic Subunit of Protein Kinase 2 and Carries Histone-Like Lysine-Methylated Mark

Summary

The X-chromosome-linked clusters of the tandemly repeated testis-specific Stellate genes of Drosophila melanogaster, encoding proteins homologous to the regulatory β-subunit of the protein kinase casein kinase 2 (CK2), are repressed in wild-type males. Derepression of Stellate genes in the absence of the Y chromosome or Y-linked crystal locus (crystal line) causes accumulation of abundant protein crystals in testes and different meiotic abnormalities, which lead to partial or complete male sterility. To understand the cause of abnormalities in chromosome behavior owing to Stellate overexpression, we studied subcellular localization of Stellate proteins by biochemical fractionation and immunostaining of whole testes. We showed that, apart from the known accumulation of Stellate in crystalline form, soluble Stellate was located exclusively in the nucleoplasm, whereas Stellate crystals were located mainly in the cytoplasm. Coimmunoprecipitation experiments revealed that the α-subunit of the protein kinase CK2 (CK2α) was associated with soluble Stellate. Interaction between soluble Stellate and CK2α in the nucleus could lead to modulations in the phosphorylation of nuclear targets of CK2 and abnormalities in the meiotic segregation of chromosomes. We also observed that Stellate underwent lysine methylation and mimicked trimethyl-H3K9 epigenetic modification of histone H3 tail.     

Role of svp in Drosophila Pericardial Cell Growth

The Drosophila dorsal vessel is a segmentally repeated linear organ, in which seven-up (svp) is expressed in two pairs of cardioblasts and two pairs of pericardial cells in each segment. Under the control of hedgehog (hh) signaling from the dorsal ectoderm, svp participates in diversifying cardioblast identities within each segment. In this experiment, the homozygous embryos of svp mutants exhibited an increase in cell size of Eve positive pericardial cells (EPCs) and a disarranged expression pattern, while the cardioblasts pattern of svp-lacZ expression was normal. In the meantime, the DA1 muscle founders were absent in some segments in svp mutant embryos, and the dorsal somatic muscle patterning was also severely damaged in the late stage mutant embryos, suggesting that svp is required for the differentiation of Eve-positive pericardial cells and DA1 muscle founders and may have a role in EPC cell growth.     

Wing morphology and fluctuating asymmetry depend on the host plant in cactophilic Drosophila

As in most insect groups, host plant shifts in cactophilic Drosophila represent environmental challenges as flies must adjust their developmental programme to the presence of different chemical compounds and/or to a microflora that may differ in the diversity and abundance of yeasts and bacteria. In this context, wing morphology provides an excellent opportunity to investigate the factors that may induce changes during development. In this work, we investigated phenotypic plasticity and developmental instability of wing morphology in flies on the cactophilic Drosophila buzzatii and Drosophila koepferae raised on alternative breeding substrates. We detected significant differences in wing size between and within species, and between flies reared on different cactus hosts. However, differences in wing shape between flies emerged from different cactus hosts were not significant either in D. buzzatii or in D. koepferae. Our results also showed that morphological responses involved the entire organ, as variation in size and shape correlated between different portions of the wing. Finally, we studied the effect of the rearing cactus host on developmental instability as measured by the degree of fluctuating asymmetry (FA). Levels of FA in wing size were significantly greater in flies of both species reared in non-preferred when compared with those reared in preferred host cacti. Our results are discussed in the framework of an integrative view aimed at investigating the relevance of host plant shifts in the evolution of the guild of cactophilic Drosophila species that diversified in South America.     

Host-plant shifts and adult survival in the cactus breeding Drosophila mojavensis

Abstract. 1. In order to gain insight into how Drosophila mojavensis Patterson and Crow (which lives on the rotting tissue of cactus) successfully shifted host plants, from an Opuntia species to columnar cactus species, over evolutionary time, specific components of columnar cactus and Optunia tussue were examined for their effects on adult longevity.
2. The availability of free sugars affects the survival of adult D.mojavensis . The addition of a sugar to columnar cactus tissue significantly increased the longevity of adults that fed on those tissues. This increase in adult longevity was equal to the longevity observed on unsupplemented Opuntia tissue, which has free sugars present.
3. Live microorganisms added to Opuntia tissue had a slight detrimental effect on adult longevity (longevity was decreased by approximately 1 week).
4. Low concentrations of atmospheric ethanol (independent of diet) increased the longevity of adult D.mojavensis to levels comparable in magnitude to that provided by the addition of free sugars to the diet.
5. This information and the apparent lack of a year-round supply of free sugars for D.mojavensis in nature suggests that the ethanol (produced by fermentation) rather than free sugars per se is the most important component of rotting cactus tissue for the survival of this species and may explain its successful host-plant shift.