The genetic basis for mating-induced sex differences in starvation resistance in Drosophila melanogaster

Multiple genetic and environmental factors interact to influence starvation resistance, which is an important determinant of fitness in many organisms, including Drosophila melanogaster. Recent studies have revealed that mating can alter starvation resistance in female D. melanogaster, but little is known about the behavioral and physiological mechanisms underlying such mating-mediated changes in starvation resistance. In the present study, we first investigated whether the effect of mating on starvation resistance is sex-specific in D. melanogaster. As indicated by a significant sex × mating status interaction, mating increased starvation resistance in females but not in males. In female D. melanogaster, post-mating increase in starvation resistance was mainly attributed to increases in food intake and in the level of lipid storage relative to lean body weight. We then performed quantitative genetic analysis to estimate the proportion of the total phenotypic variance attributable to genetic differences (i.e., heritability) for starvation resistance in mated male and female D. melanogaster. The narrow-sense heritability (h²) of starvation resistance was 0.235 and 0.155 for males and females, respectively. Mated females were more resistant to starvation than males in all genotypes, but the degree of such sexual dimorphism varied substantially among genotypes, as indicated by a significant sex × genotype interaction for starvation resistance. Cross-sex genetic correlation was greater than 0 but less than l for starvation resistance, implying that the genetic architecture of this trait was partially shared between the two sexes. For both sexes, starvation resistance was positively correlated with longevity and lipid storage at genetic level. The present study suggests that sex differences in starvation resistance depend on mating status and have a genetic basis in D. melanogaster.     

Characterization,bioinformatic analysis and dithiocarbamate inhibition studies of two new α-carbonic anhydrases,CAH1 and CAH2, from the fruit fly Drosophila melanogaster

Carbonic anhydrases (CAs) are essential and ubiquitous enzymes. Thus far, there are no articles on characterization of Drosophila melanogaster α-CAs. Data from invertebrate CA studies may provide opportunities for anti-parasitic drug development because α-CAs are found in many parasite or parasite vector invertebrates. We have expressed and purified D. melanogaster CAH1 and CAH2 as proteins of molecular weights 30 kDa and 28 kDa. CAH1 is cytoplasmic whereas CAH2 is a membrane-attached protein. Both are highly active enzymes for the CO₂ hydration reaction, being efficiently inhibited by acetazolamide. CAH2 in the eye of D. melanogaster may provide a new animal model for CA-related eye diseases. A series of dithiocarbamates were also screened as inhibitors of these enzymes, with some representatives showing inhibition in the low nanomolar range.     

Complex gene organization of synaptic protein SNAP-25 in Drosophila melanogaster

The evolutionarily conserved protein SNAP-25 (synaptosome-associated protein 25 kDa (kilodaltons)) is a component of the protein complex involved in the docking and/or fusion of synaptic vesicles in nerve terminals. We report here that the SNAP-25 gene (Snap) in the fruit fly Drosophila melanogaster has a complex organization with eight exons spanning more than 120 kb (kilobases). The exon boundaries coincide with those of the chicken SNAP-25 gene (Bark, 1993). Only a single exon 5 has been found in Drosophila, whereas human, rat, chicken, zebrafish and goldfish have two alternatively spliced versions of this exon. In situ hybridization and immunocytochemistry to whole mount embryos show that SNAP-25 mRNA and protein are detected in stage 14 and later developmental stages, and are mainly localized to the ventral nerve cord. Thus, Snap has an evolutionarily conserved and complex gene organization, and its onset of expression in Drosophila melanogaster correlates with a time in neuronal development when synapses begin to be formed and when other synapse-specific genes are switched on.     

Crystal structure of the pheromone Er-13 from the ciliate Euplotes raikovi,with implications for a protein–protein association model in pheromone/receptor interactions

In the ciliate Euplotes raikovi, water-borne protein pheromones promote the vegetative cell growth and mating by competitively binding as autocrine and heterologous signals to putative cell receptors represented by membrane-bound pheromone isoforms. A previously determined crystal structure of pheromone Er-1 supported a pheromone/receptor binding model in which strong protein–protein interactions result from the cooperative utilization of two distinct types of contact interfaces that arrange molecules into linear chains, and these into two-dimensional layers. We have now determined the crystal structure of a new pheromone, Er-13, isolated from cultures that are strongly mating reactive with cultures source of pheromone Er-1. The comparison between the Er-1 and Er-13 crystal structures reinforces the fundamental of the cooperative model of pheromone/receptor binding, in that the molecules arrange into linear chains taking a rigorously alternate opposite orientation reflecting the presumed mutual orientation of pheromone and receptor molecules on the cell surface. In addition, the comparison provides two new lines of evidence for a univocal rationalization of observations on the different behaviour between the autocrine and heterologous pheromone/receptor complexes. (i) In the Er-13 crystal, chains do not form layers which thus appear to be an over-structure unique to the Er-1 crystal, not essential for the pheromone signalling mechanisms. (ii) In both crystal structures, the intra-chain interfaces are equally derived from burying amino-acid side-chains mostly residing on helix-3 of the three-helical pheromone fold. This helix is thus identified as the key structural motif underlying the pheromone activity, in line with its tight intra- and interspecific structural conservation.     

Role of Bacopa monnieri in the temporal regulation of oxidative stress in clock mutant (cryb) of Drosophila melanogaster

Accruing evidences imply that circadian organization of biochemical, endocrinological, cellular and physiological processes contribute to wellness of organisms and in the development of pathologies such as malignancy, sleep and endocrine disorders. Oxidative stress is known to mediate a number of diseases and it is notable to comprehend the orchestration of circadian clock of a model organism of circadian biology, Drosophila melanogaster, under oxidative stress. We investigated the nexus between circadian clock and oxidative stress susceptibility by exposing D. melanogaster to hydrogen peroxide (H₂O₂) or rotenone; the reversibility of rhythms following exposure to Bacopa monnieri extract (ayurvedic medicine rich in antioxidants) was also investigated. Abolishment of 24 h rhythms in physiological response (negative geotaxis), oxidative stress markers (protein carbonyl and thiobarbituric acid reactive substances) and antioxidants (superoxide dismutase, catalase, glutathione-S-transferase and reduced glutathione) were observed under oxidative stress. Furthermore, abolishment of per mRNA rhythm in H₂O₂ treated wild type flies and augmented susceptibility to oxidative stress in clock mutant (cry^b) flies connotes the role of circadian clock in reactive oxygen species (ROS) homeostasis. Significant reversibility of rhythms was noted following B. monnieri treatment in wild type flies than cry^b flies. Our experimental approach revealed a relationship involving oxidative stress and circadian clock in fruit fly and the utility of Drosophila model in screening putative antioxidative phytomedicines prior to their use in mammalian systems.     

Potential impact of an exceptional bloom of Karenia mikimotoi on dissolved oxygen levels in waters off western Ireland

In the summer of 2005 an exceptional bloom of the dinoflagellate Karenia mikimotoi occurred along Ireland's Atlantic seaboard and was associated with the mass mortality of both benthic and pelagic marine life. Oxygen depletion, cellular toxicity and physical smothering, are considered to be the main factors involved in mortality. In this paper we use a theoretical approach based on stoichiometry (the Anderson ratio) and an average K. mikimotoi cellular carbon content of 329 pg C cell⁻¹ (n = 20) to calculate the carbonaceous and nitrogenous oxygen demand following bloom collapse. The method was validated against measurements of biochemical oxygen demand and K. mikimotoi cell concentration. The estimated potential oxygen utilisation (POU) was in good agreement with field observations across a range of cell concentrations. The magnitude of POU following bloom collapse, with the exception of three coastal areas, was considered insufficient to cause harm to most marine organisms. This indicates that the widespread occurrence of mortality was primarily due to other factors such as cellular toxicity and/or mucilage production, and not oxygen depletion or related phenomena. In Donegal Bay, Kilkieran Bay and inner Dingle Bay, where cell densities were in the order of 10⁶ cells L⁻¹, estimated POU was sufficient to cause hypoxia. Of the three areas, Donegal Bay is considered to be the most vulnerable due to its hydrographic characteristics (seasonally stratified, weak residual flow) and hypoxic conditions (2.2 mg L⁻¹ O₂) were directly observed in the Bay post bloom collapse. Here, depending on the time of bloom collapse, depressed DO levels could persist for weeks and continue to have a potentially chronic impact on the Bay.     

RANKL/OPG in primary cultures of osteoblasts from post-menopausal women. Differences between osteoporotic hip fractures and osteoarthritis

The OPG/RANKL/RANK system is important in the balance between bone formation and resorption.We used primary human osteoblasts (hOBs) cells to examine the impact of 17-β-estradiol (E2) or/and 1,25-dihydroxyvitamin D (1,25D) in OPG/RANKL system in 28 post-menopausal (PM) women; (a) with hip fracture (OP) or (b) with osteoarthritis (OA). The hOB from OP patients proliferated slower during the first stage, than the OA women (31.5 ± 2.6 and 21.4 ± 1.3 days, respectively, p < 0.05). The OP group secreted significantly higher OPG protein levels than the OA women (10.1 ± 2.6 and 4.4 ± 0.8 pmol/L, respectively, p < 0.05). The 1,25D and 1,25D+E2 induce an increase in RANKL and RANKL/OPG mRNA expression in OP patients above 200% (p < 0.05).HOBs from the osteoporotic hip initially proliferate slower but after reaching the first cellular confluence, the proliferation rate is equal in both groups. Furthermore, hOBs from hips with OP present a higher protein secretion of OPG, and higher RANKL and RANKL/OPG expression ratio in response to 1,25D and 1,25D+E2, than hOBs from OA women. All this could suggest that the greater bone loss that characterizes OP patients can be mediated due to differences in the secretion and expression of the RANKL/OPG system in response to different stimuli.     

Impaired trafficking of the very low density lipoprotein receptor caused by missense mutations associated with dysequilibrium syndrome

Dysequilibrium syndrome (DES, OMIM 224050) is a genetically heterogeneous condition that combines autosomal recessive non-progressive cerebellar ataxia with mental retardation. The subclass dysequilibrium syndrome type 1 (CAMRQ1) has been attributed to mutations in the VLDLR gene encoding the very low density lipoprotein receptor (VLDLR). This receptor is involved in the Reelin signaling pathway that guides neuronal migration in the cerebral cortex and cerebellum. Three missense mutations (c.1459G > T; p.D487Y, c.1561G > C; p.D521H and c.2117G > T; p.C706F) have been previously identified in VLDLR gene in patients with DES. However, the functional implications of those mutations are not known and therefore we undertook detailed functional analysis to elucidate the cellular mechanisms underlying their pathogenicity. The mutations have been generated by site-directed mutagenesis and then expressed in cultured cell lines. Confocal microscopy and biochemical analysis have been employed to examine the subcellular localization and functional activities of the mutated proteins relative to wild type. Our results indicate that the three missense mutations lead to defective intracellular trafficking and ER retention of the mutant VLDLR protein. This trafficking impairment prevents the mutants from reaching the plasma membrane and binding exogenous Reelin, the initiating event in Reelin signaling. Collectively, our results provide evidence that ER quality control is involved in the functional inactivation and underlying pathogenicity of these DES-associated mutations in the VLDLR.     

Investigation of various N-heterocyclic substituted piperazine versions of 5/7-{[2-(4-aryl-piperazin-1-yl)-ethyl]-propyl-amino}-5,6,7,8-tetrahydro-naphthalen-2-ol: Effect on affinity and selectivity for dopamine D3 receptor

Here we report on the design and synthesis of several heterocyclic analogues belonging to the 5/7-{[2-(4-aryl-piperazin-1-yl)-ethyl]-propyl-amino}-5,6,7,8-tetrahydro-naphthalen-2-ol series of molecules. Compounds were subjected to [³H]spiperone binding assays, carried out with HEK-293 cells expressing either D2 or D3 dopamine receptors, in order to evaluate their inhibition constant (K_i) at these receptors. Results indicate that N-substitution on the piperazine ring can accommodate various substituted indole rings. The results also show that in order to maintain high affinity and selectivity for the D3 receptor the heterocyclic ring does not need to be connected directly to the piperazine ring as the majority of compounds included here are linked either via an amide or a methylene linker to the heterocyclic moiety. The enantiomers of the most potent racemic compound 10e exhibited differential activity with (?)-10e (K_i; D2 = 47.5 nM, D3 = 0.57 nM) displaying higher affinity at both D2 and D3 receptors compared to its enantiomer (+)-10e (K_i; D2 = 113 nM, D3 = 3.73 nM). Additionally, compound (?)-10e was more potent and selective for the D3 receptor compared to either 7-OH-DPAT or 5-OH-DPAT. Among the bioisosteric derivatives, the indazole derivative 10g and benzo[b]thiophene derivative 10i exhibited the highest affinity for D2 and D3 receptors. In the functional GTPγS binding study, one of the lead molecules, (?)-15, exhibited potent agonist activity at both D2 and D3 receptors with preferential affinity at D3.     

Characterization of a recombinant N-acetylgalactosamine-6-sulfate sulfatase produced in E. coli for enzyme replacement therapy of Morquio A disease

Mucopolysaccharidosis IVA (MPS IVA) is a lysosomal storage disease caused by the deficiency of N-acetylgalactosamine-6-sulfate sulfatase (GALNS) enzyme. Currently, specific therapies are not available for MPS IVA patients. In this study, a biologically active recombinant GALNS enzyme (rGALNS) produced in Escherichia coli was purified through a two-step chromatography process. The effect of temperature and pH on purified rGALNS stability was evaluated, as well as the stability in human serum. Finally, the uptake of rGALNS by HEK 293 cells and MPS IVA fibroblasts was evaluated. The use of a semi-continuous process allowed the production of an active extracellular rGALNS, which was used for protein purification. The purified rGALNS showed a specific activity of 0.29 U mg^?1 and a production yield of 0.78 mg L^?1. The rGALNS presented an optimal pH of 5.5 and was stable for 8 days at 4 °C. In human serum it was stable for up to 6 h. rGALNS was not taken up by the cultured cells, suggesting that N-linked oligosaccharides are not necessary for the production of an active enzyme or enzyme stability but for the cell uptake of protein. This study shows the first characterization of rGALNS produced by E. coli, and provides important information about purification, stability, and glycosylations effect for this type of enzymes.     

Opposite changes in cannabinoid CB1 and CB2 receptor expression in human gliomas

Gliomas are the most important group of malignant primary brain tumors and one of the most aggressive forms of cancer. During the last years, several studies have demonstrated that cannabinoids induce apoptosis of glioma cells and inhibit angiogenesis of gliomas in vivo. As the effects of cannabinoids rely on CB₁ and CB₂ receptors activation, the aim of the present study was to investigate both receptors protein expression in cellular membrane homogenates of human glial tumors using specific antibodies raised against these proteins. Additionally, we studied the functionality of the cannabinoid receptors in glioblastomas by using WIN 55,212-2 stimulated [³⁵S]GTPγS binding.Western blot analysis showed that CB₁ receptor immunoreactivity was significantly lower in glioblastoma multiforme (?43%, n = 10; p < 0.05) than in normal post-mortem brain tissue (n = 16). No significant differences were found for astrocytoma (n = 6) and meningioma (n = 8) samples. Conversely, CB₂ receptor immunoreactivity was significantly greater in membranes of glioblastoma multiforme (765%, n = 9; p < 0.05) and astrocytoma (471%, n = 4; p < 0.05) than in control brain tissue (n = 10). Finally, the maximal stimulation of [³⁵S]GTPγS binding by WIN 55,212-2 was significantly lower in glioblastomas (134 ± 4%) than in control membranes (183 ± 2%; p < 0.05). The basal [³⁵S]GTPγS binding and the EC₅₀ values were not significantly different between both groups.The present results demonstrate opposite changes in CB₁ and CB₂ receptor protein expression in human gliomas. These changes may be of interest for further research about the therapeutic effects of cannabinoids in glial tumors.     

Elevation of cellular O-GlcNAcylation level by a potent and selective O-GlcNAcase inhibitor based on tetrahydroimidazopyridine scaffold

Protein O-GlcNAc glycosylation is a ubiquitous post-translational modification in metazoans. O-GlcNAcase (OGA), which is responsible for removing O-GlcNAc from serine or threonine residues, plays a key role in O-GlcNAc metabolism. Potent and selective O-GlcNAcase (OGA) inhibitors are useful tools for investigating the role of this modification in a broad range of cellular processes, and may also serve as drug candidates for treatment of neurodegenerative diseases. Biological screening of the gluco-configured tetrahydroimidazopyridine derivatives identified a compound as a potent and competitive inhibitor of human O-GlcNAcase (OGA) with a K_i of 5.9 μM, and it also displayed 28-fold selectivity for human OGA over human lysosomal β-hexosaminidase A (Hex A, K_i = 163 μM). In addition, cell-based assay revealed that this compound was cell-permeant and effectively induced cellular hyper-O-GlcNAcylation at 10 μM concentration.     

Redox status of the liver and kidney of 2,2-dichlorovinyl dimethyl phosphate (DDVP) treated rats

The effect of 2,2-dichlorovinyl dimethyl phosphate on redox homeostasis in male rats was investigated. Rats were grouped into four: A, B, C and D where A (the control) received orally 1 ml of distilled water; B, C and D (test groups) received orally 2.5, 5 and 10 mg/kg body weight of DDVP respectively for 28 days. DDVP administration significantly reduced (P < 0.05) the alkaline phosphatase activity in the liver and kidney with corresponding increases in the serum. Acid phosphatase activity increased significantly (P < 0.05) in liver and kidney, while there was no significant change (P > 0.05) in the serum acid phosphatase activity. There was also a significant decrease (P < 0.05) in the activities of superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase in the liver and kidney. Liver and kidney levels of GSH, vitamins C and E were also significantly reduced (P < 0.05). Serum malonidialdehyde and lipid hydroperoxide also increased significantly (P < 0.05) in all DDVP treated groups. The available data from this study revealed that DDVP brings about its toxicity through depletion of the antioxidant systems and thus exposing the cells and cellular macromolecules to oxidative attacks by reactive oxygen species generated either from its metabolites or other in vivo means.     

Vitamin E and rutin synergistically inhibit expression of vascular endothelial growth factor through down-regulation of binding activity of activator protein-1 in human promyelocytic leukemia (HL-60) cells

Reactive oxygen species (ROS) are strong inducers of the angiogenic hormone vascular endothelial growth factor (VEGF). Although, rutin (R) in combination with vitamin E (VE) has been shown to synergistically inhibit oxidative damage, it is unclear whether the combination of R and VE (R + VE) inhibits VEGF secretion in tumor cells. Using a human promyelocytic leukemia (HL-60) cell line, we showed that R in combination with VE synergistically decreased the expressions of VEGF protein and mRNA. We also demonstrated that R + VE significantly decreased the binding capacity of nuclear factor-activator protein-1 (AP-1) to the VEGF gene promoter and decreased the expression of c-Jun protein. Furthermore, we demonstrated that R + VE synergistically reduced insulin receptor substrate-1 (IRS-1) protein expression in HL-60 cells. The decrease of ROS was only partially associated with the decrease of VEGF secreted (r² = 0.12, P = 0.083). Thus, the present results indicate that R in combination with VE attenuates VEGF expression in HL-60 cells and that this effect is mediated by a decreased binding activity of AP-1 through down-regulation of protein expression of insulin-like growth factor 1 receptor (IGF1-R)/IRS-1, while the antioxidant activity of R + VE appears to play a minor role.     

Toxin production,retention, and extracellular release by Dinophysis acuminata during extended stationary phase and culture decline

Dinophysis spp. produce diarrhetic shellfish poisoning (DSP) toxins and pectenotoxins. The extent to which the dinoflagellate cells retain their toxicity in stationary phase, a period when cells are most toxic, and their transition into cell death is not known. Here we present results on the production, recycling, retention, and release of toxins from a monoculture of Dinophysis acuminata during these two important stages. Once stationary phase was reached, cultures were divided between light and dark treatments to identify if light influenced toxin dynamics. Light was required for long-term cell maintenance (>2 months) of D. acuminata in the absence of prey, however, in the dark, cells in stationary phase survived on reserves alone for four weeks before beginning to decline. Cells maintained relatively constant levels of intracellular OA (0.39 ± 0.03 pg/cell, 0.44 ± 0.05 pg/cell), DTX1 (0.45 ± 0.09 pg/cell, 0.64 ± 0.10 pg/cell) and PTX2 (10.4 ± 1.4 pg/cell, 11.0 ± 1.9 pg/cell) in the dark and light treatments, respectively, throughout stationary phase and into culture decline. Toxin production was only apparent during late exponential and early stationary growth when cells were actively dividing. In general, the concentration of dissolved (extracellular) toxin in the medium significantly increased upon culture aging and decline; cells did not appear to be actively or passively releasing toxin during stationary phase, but rather extracellular release was likely a result of cell death. Light availability did not have an apparent effect on toxin production, quotas, or intracellular vs. extracellular distribution. Together these results suggest that a bloom of D. acuminata would retain its cellular toxicity or potency as long as the population is viable, and that cells under conditions of low light (e.g., at the boundary or below euphotic zone) and/or minimal prey could maintain toxicity for extended periods.     

Magnetic susceptibility of iron in malaria-infected red blood cells

During intra-erythrocytic maturation, malaria parasites catabolize up to 80% of cellular haemoglobin. Haem is liberated inside the parasite and converted to haemozoin, preventing haem iron from participating in cell-damaging reactions. Several experimental techniques exploit the relatively large paramagnetic susceptibility of malaria-infected cells as a means of sorting cells or investigating haemoglobin degradation, but the source of the dramatic increase in cellular magnetic susceptibility during parasite growth has not been unequivocally determined. Plasmodium falciparum cultures were enriched using high-gradient magnetic fractionation columns and the magnetic susceptibility of cell contents was directly measured. The forms of haem iron in the erythrocytes were quantified spectroscopically. In the 3D7 laboratory strain, the parasites converted approximately 60% of host cell haemoglobin to haemozoin and this product was the primary source of the increase in cell magnetic susceptibility. Haemozoin iron was found to have a magnetic susceptibility of (11.0 ± 0.9) × 10^? 3 mL mol^? 1. The calculated volumetric magnetic susceptibility (SI units) of the magnetically enriched cells was (1.88 ± 0.60) × 10^? 6 relative to water while that of uninfected cells was not significantly different from water. Magnetic enrichment of parasitised cells can therefore be considered dependent primarily on the magnetic susceptibility of the parasitised cells.     

The role of androst-5-ene-3β,17β-diol (androstenediol) in cell proliferation in endometrium of women with polycystic ovary syndrome

Women with polycystic ovary syndrome (PCOS) show high prevalence of endometrial hyperplasia and adenocarcinoma. Endometrial proliferation is increased, evaluated by high levels of Ki67 (cell cycle marker) and low levels of p27 (negative regulator of cell cycle). Nevertheless, endometrial changes in cyclin D1 (positive regulator of cell cycle) in PCOS-women are not described. Androst-5-ene-3β,17β-diol (androstenediol), steroid with estrogenic activity present in endometria, could be related to increased endometrial cell proliferation. The objective of this study was to determine protein content of cyclin D1 and androstenediol levels in endometria from PCOS and control-women and to evaluate the possible mechanism favoring cell proliferation associated with hormonal characteristics of patients. Therefore, cyclin D1 protein content in PCOS-women and control-endometrial tissue were assessed by western blot and immunohistochemistry. The androstenediol levels were evaluated by ELISA. To further analyze the effect of steroids (androstenediol, 17β-estradiol, testosterone) in cell proliferation, levels of proteins cyclin D1, p27 and Ki67 were evaluated in an in vitro model of stromal endometrial cells T-HESC and St-T1b. An increase in cyclin D1 and androstenediol was observed in tissues from PCOS-women relative to control group (p < 0.05). In the in vitro model, androstenediol exerted increase in cyclin D1 (p < 0.05) and a decrease in p27 protein level (p < 0.05), while Ki67 in St-T1b cells increased under this stimulus (p < 0.05). Testosterone produces opposite effects in the levels of the above markers (p < 0.05). Therefore, the hormonal imbalance associated with this syndrome could alter endometrial tissue homeostasis, promoting cell proliferation. Androstenediol is a molecule that could be involved by stimulating proliferation, whereas testosterone elicits a role of cell cycle repressor.     

Comparison of the thermal performance between a population of the olive fruit fly and its co-adapted parasitoids

Long-term separation of a host from its native parasitoids may result in divergent thermal adaptation between host and parasitoid. The olive fruit fly, Bactrocera oleae (Rossi), most likely originated from Sub-Saharan Africa, but has since had a long invasion history in cultivated olives that spans geographical barriers and continents. This study compared three major thermal performance profiles (development, survival, and reproduction) across a wide range of temperatures (10–34 °C) among a Californian population of the olive fruit fly and two African parasitoids, Psyttalia lounsburyi (Silvestri) and Psyttalia humilis (Silvestri), believed to have co-adapted with the fruit fly in its native range. Temperature ranges for the development and survival were 10–30 °C for the fly, 10–28 °C for P. lounsburyi, and 14–32 °C for P. humilis. There was no difference in any thermal performance measured between two P. humilis populations (Kenya and Namibia) tested. The most suitable temperature ranges for reproduction were 22–30 °C for the fly, 18–32 °C for P. humilis, and 18–26 °C for P. lounsburyi. The results showed slight differences in the thermal profiles among olive fruit fly and both parasitoids species, with P. humilis being more heat tolerant whereas P. lounsburyi was less heat tolerant than the fruit fly. The results are discussed with respect to thermal co-adaptation and classical biological control of the olive fruit fly.