Biomedical subjects

Ryszard Maleszka

Publications and source records attributed to Ryszard Maleszka.

13 recordsLinked to original sources

PubMed2026

Sex-biased DNA methylation in small hive beetles (Aethina tumida).

DNA methylation is an important epigenomic modification that significantly influences various cellular and organismal functions. In this study, we investigate the methylome of the small hive beetle, Aethina tumida. Our analysis reveals an average of 58,306 CpG methylation marks per beetle, representing approximately 0.99% of the genome's total CpGs. Notably, 85.4% of these methylation marks are located within genic regions on autosomes, with similar rates observed in both male and female beetles. However, male beetles exhibit a lower number of methylation marks and upregulated genes on Chromosome X when compared to female beetles. To evaluate the impact of epialleles on methylation, we identified 5828 associations between SNPs and methylation, with genotypes accounting for 39.2% of the variation observed at highly methylated sites. Interestingly, unfertilised eggs display slightly higher levels of DNA methylation compared to adult beetles, whereas embryos show methylation levels that are only about half of those in adults. This suggests that DNA methylation is dynamic during early development.

Animals↗

PubMed2006

Functional CpG methylation system in a social insect.

DNA methylation systems are well characterized in vertebrates, but methylation in Drosophila melanogaster and other invertebrates remains controversial. Using the recently sequenced honey bee genome, we present a bioinformatic, molecular, and biochemical characterization of a functional DNA methylation system in an insect. We report on catalytically active orthologs of the vertebrate DNA methyltransferases Dnmt1 and Dnmt3a and b, two isoforms that contain a methyl-DNA binding domain, genomic 5-methyl-deoxycytosine, and CpG-methylated genes. The honey bee provides an opportunity to study the roles of methylation in social contexts.

Amino Acid Sequence↗

PubMed2006

Evolution of the Yellow/Major Royal Jelly Protein family and the emergence of social behavior in honey bees.

The genomic architecture underlying the evolution of insect social behavior is largely a mystery. Eusociality, defined by overlapping generations, parental brood care, and reproductive division of labor, has most commonly evolved in the Hymenopteran insects, including the honey bee Apis mellifera. In this species, the Major Royal Jelly Protein (MRJP) family is required for all major aspects of eusocial behavior. Here, using data obtained from the A. mellifera genome sequencing project, we demonstrate that the MRJP family is encoded by nine genes arranged in an approximately 60-kb tandem array. Furthermore, the MRJP protein family appears to have evolved from a single progenitor gene that encodes a member of the ancient Yellow protein family. Five genes encoding Yellow-family proteins flank the genomic region containing the genes encoding MRJPs. We describe the molecular evolution of these protein families. We then characterize developmental-stage-specific, sex-specific, and caste-specific expression patterns of the mrjp and yellow genes in the honey bee. We review empirical evidence concerning the functions of Yellow proteins in fruit flies and social ants, in order to shed light on the roles of both Yellow and MRJP proteins in A. mellifera. In total, the available evidence suggests that Yellows and MRJPs are multifunctional proteins with diverse, context-dependent physiological and developmental roles. However, many members of the Yellow/MRJP family act as facilitators of reproductive maturation. Finally, it appears that MRJP protein subfamily evolution from the Yellow protein family may have coincided with the evolution of honey bee eusociality.

Animals↗

PubMed2006

Function and evolution of a gene family encoding odorant binding-like proteins in a social insect, the honey bee (Apis mellifera).

The remarkable olfactory power of insect species is thought to be generated by a combinatorial action of two large protein families, G protein-coupled olfactory receptors (ORs) and odorant binding proteins (OBPs). In olfactory sensilla, OBPs deliver hydrophobic airborne molecules to ORs, but their expression in nonolfactory tissues suggests that they also may function as general carriers in other developmental and physiological processes. Here we used bioinformatic and experimental approaches to characterize the OBP-like gene family in a highly social insect, the Western honey bee. Comparison with other insects shows that the honey bee has the smallest set of these genes, consisting of only 21 OBPs. This number stands in stark contrast to the more than 70 OBPs in Anopheles gambiae and 51 in Drosophila melanogaster. In the honey bee as in the two dipterans, these genes are organized in clusters. We show that the evolution of their structure involved frequent intron losses. We describe a monophyletic subfamily of OBPs where the diversification of some amino acids appears to have been accelerated by positive selection. Expression profiling under a wide range of conditions shows that in the honey bee only nine OBPs are antenna-specific. The remaining genes are expressed either ubiquitously or are tightly regulated in specialized tissues or during development. These findings support the view that OBPs are not restricted to olfaction and are likely to be involved in broader physiological functions.

Amino Acid Sequence↗

PubMed2006

Chemosensory proteins in the honey bee: Insights from the annotated genome, comparative analyses and expressional profiling.

Small chemosensory proteins (CSPs) belong to a conserved, but poorly understood protein family that has been implicated in transporting chemical stimuli within insect sensilla. However, their expression patterns suggest that these molecules are also critical for other functions including early development. Here we used both bioinformatics and experimental approaches to characterize the CSP gene family in a social insect, the Western honey bee Apis mellifera, and then compared its members to CSPs in other arthropods. The number of CSPs in the honey bee genome (six) is similar to that found in the sequenced dipteran species (four-seven), but is much lower than the number of CSPs in the moth or in the beetle (around 20 each). These differences seem to be the result of lineage specific expansions. Our analysis of CSPs in a number of arthropods reveals a conserved gene family found in both Mandibulates and Chelicerates. Expressional profiling in diverse tissues and throughout development reveals broader than expected patterns of expression with none of the CSPs restricted to the antennae and one found only in the queen ovaries and in embryos. We conclude that CSPs are multifunctional context-dependent proteins involved in diverse cellular processes ranging from embryonic development to chemosensory signal transduction. Some CSPs may function in cuticle synthesis, consistent with their evolutionary origins in the arthropods.

Amino Acid Sequence↗

PubMed2005

Effects of carbon dioxide narcosis on ovary activation and gene expression in worker honeybees, Apis mellifera.

In an effort to uncover genes associated with ovary activation in honey bee workers, the extent to which eight candidate genes co-varied in their expression with experimentally-induced changes in worker reproductive state was examined. Groups of caged, queenless workers narcotized with CO(2) on consecutive days early in adult life showed a significantly lower level of ovary activation than did groups of untreated workers. This same experimental treatment, by contrast, is known to accelerate ovary activation and induce egg laying in virgin honey bee queens--an observation that suggests that CO(2) narcosis has contrasting effects in queen versus worker ovary activation. Experimentally-induced changes to worker reproductive state were associated with changes in gene expression. Vitellogenin, an egg yolk precursor, and transferrin, an iron transporter, were two transcripts found to be significantly down-regulated as a function of the ovary-inhibiting treatment. CO(2) narcosis did not effect the expression of six other genes selected as putative markers for processes that may underlie ovary activation. The show that the expression of vitellogenin and transferrin is correlated with ovary activation in workers, and may therefore be part of the gene network involved in the regulatory control of functional sterility in honeybees.

Animals↗

PubMed2005

The effects of rearing temperature on developmental stability and learning and memory in the honey bee, Apis mellifera.

Honey bee workers maintain the brood nest of their colony within a narrow temperature range of 34.5+/-1.5 degrees C, implying that there are significant fitness costs if brood is reared outside the normal range. However, the effects of abnormal incubation temperatures are subtle and not well documented. Here we show that short-term learning and memory abilities of adult workers are affected by the temperature they experienced during pupal development. In contrast, long-term learning and memory is not significantly affected by rearing temperature. Furthermore, we could detect no effects of incubation temperature on fluctuating asymmetry, as a measure of developmental stability, in workers, queens or drones. We conclude that the most important consequence of abnormal rearing temperatures are subtle neural deficiencies affecting short-term memory rather than physical abnormalities.

Animals↗

PubMed2005

Microarray and real-time PCR analyses of gene expression in the honeybee brain following caffeine treatment.

To test the idea that caffeine might induce changes in gene expression in the honeybee brain, we contrasted the transcriptional profiles of control and caffeine-treated brains using high-throughput cDNA microarrays. Additional quantitative real-time PCR was performed on a subset of eight transcripts to visualize the temporal changes induced by caffeine. Genes that were significantly upregulated in caffeine-treated brains included those involved in synaptic signaling (GABA:Na symporter, dopamine D2R-like receptor, and synapsin), cytoskeletal modifications (kinesin and microtubule motors), protein translation (ribosomal protein RpL4, elongation factors), and calcium-dependent processes (calcium transporter, calmodulin- dependent cyclic nucleotide phosphodiesterase). In addition, our study uncovered a number of novel, caffeine-inducible genes that appear to be unique to the honeybee. Time-dependent profiling of caffeine-sensitive gene expression shows significant upregulation 1 h after treatment followed by moderate downregulation after 4 h with no additional changes occuring after 24 h. Our results provide initial evidence that the dopaminergic system and calcium exchange are the main targets of caffeine in the honeybee brain and suggest that molecular responses to caffeine in an invertebrate brain are similar to those in vertebrate organisms.

Animals↗

PubMed2004

Effects of NMDA receptor antagonists on olfactory learning and memory in the honeybee (Apis mellifera).

In contrast to vertebrates the involvement of glutamate and N-methyl-D-aspartate (NMDA) receptors in brain functions in insects is both poorly understood and somewhat controversial. Here, we have examined the behavioural effects of two noncompetitive NMDA receptor antagonists, memantine (low affinity) and MK-801 (high affinity), on learning and memory in honeybees (Apis mellifera) using the olfactory conditioning of the proboscis extension reflex (PER). We induced memory deficit by injecting harnessed individuals with a glutamate transporter inhibitor, L-trans-2,4-PDC (L-trans-2,4-pyrrolidine dicarboxylate), that impairs long-term (24 h), but not short-term (1 h), memory in honeybees. We show that L-trans-2,4-PDC-induced amnesia is 'rescued' by memantine injected either before training, or before testing, suggesting that memantine restores memory recall rather than memory formation or storage. When injected alone memantine has a mild facilitating effect on memory. The effects of MK-801 are similar to those of L-trans-2,4-PDC. Both pretraining and pretesting injections lead to an impairment of long-term (24 h) memory, but have no effect on short-term (1 h) memory of an olfactory task. The implications of our results for memory processes in the honeybee are discussed.

Animals↗

PubMed2004

Microarray reality checks in the context of a complex disease.

A problem in analyzing microarray-based gene expression data is the separation of genes causally involved in a disease from innocent bystander genes, whose expression levels have been secondarily altered by primary changes elsewhere. To investigate this issue systematically in the context of a class of complex human diseases, we have compared microarray-based gene expression data with non-microarray-based clinical and biological data about the schizophrenias to ask whether these two approaches prioritize the same genes. We find that genes whose expression changes are deemed to be of importance from microarrays are rarely those classified as of importance from clinical, in situ, molecular, single-nucleotide polymorphism (SNP) association, knockout and drug perturbation data. This disparity is not limited to the schizophrenias but characterizes other human disease data sets. It also extends to biological validation of microarray data in model organisms, in which genome-wide phenotypic data have been systematically compared with microarray data. In addition, different bioinformatic protocols applied to the same microarray data yield quite different gene sets and thus make clinical decisions less straightforward. We discuss how progress may be improved in the clinical area by the assignment of high-quality phenotypic values to each member of a microarray-assigned gene set.

Computational Biology↗

PubMed2004

Screening for differential gene expression during the development of form-deprivation myopia in the chicken.

PURPOSE: To use the technique of differential gene display to analyze changes in gene expression that occur during the development of and recovery from form-deprivation myopia. METHODS: The differential display-reverse transcriptase-polymerase chain reaction technique was used to detect cDNAs that are differentially expressed after 24 h (including 12 h in the light) after fitting with a diffuser to induce form-deprivation myopia. Messenger RNA levels were determined by quantitative Northern blotting in retinas after 11 days of form deprivation or in retinas where the diffusers had been removed the previous day. RESULTS: Twenty-six differentially expressed genes were processed in our initial screen. Two of these, alphaB-crystallin and retinoic acid receptor-alpha, were studied further. Levels of alphaB-crystallin mRNA were increased on day 11 in retinas from form-deprived eyes relative to eyes of control chickens and were reduced to below those levels within 6 to 12 h after removal of the diffusers. Levels of retinoic acid receptor-alpha mRNA showed similar changes, except that after removal of the diffusers, the levels further increased. CONCLUSIONS: The technique of differential gene display can be used to detect changes in gene expression during the regulation of eye growth. The response of alphaB-crystallin is particularly interesting because expression increases when eye growth is high and decreases when eye growth slows.

Aging↗

PubMed2003

Inorganic carbon limitation and light control the expression of transcripts related to the CO2-concentrating mechanism in the cyanobacterium Synechocystis sp. strain PCC6803.

The cyanobacterium Synechocystis sp. strain PCC6803 possesses three modes of inorganic carbon (Ci) uptake that are inducible under Ci stress and that dramatically enhance the efficiency of the CO(2)-concentrating mechanism (CCM). The effects of Ci limitation on the mRNA transcript abundance of these inducible uptake systems and on the physiological expression of the CCM were investigated in detail in this cyanobacterium. Transcript abundance was assessed with semiquantitative and real-time reverse transcriptase-polymerase chain reaction techniques. Cells aerated with CO(2)-free air for 30 min in the light, but not in the dark, depleted the total [Ci] to near zero levels. Under these conditions, the full physiological expression of the CCM was apparent within 2 h. Transcripts for the three inducible Ci uptake systems, ndhF3, sbtA, and cmpA, showed near-maximal abundance at 15 min under Ci limitation. The transcriptional regulators, cmpR and ndhR, were more moderately expressed, whereas the rbcLXS and ccmK-N operons and ndhF4/ndhD4/chpX and ccaA genes were insensitive to the low-Ci treatment. The combined requirement of low Ci and light for the expression of several CCM-related transcripts was examined using real-time reverse transcriptase-polymerase chain reaction. CmpA, ndhF3, and sbtA were strongly expressed in the light, but not in the dark, under low-Ci conditions. We could find no evidence for induction of these or other CCM-related genes by a high-light treatment under high-CO(2) conditions. This provided evidence that high-light stress alone could not trigger the expression of CCM-related transcripts in Synechocystis sp. PCC6803. Potential signals triggering induction of the high-affinity state of the CCM are discussed.

Air↗

PubMed2002

Evaluation of differential gene expression during behavioral development in the honeybee using microarrays and northern blots.

BACKGROUND: The honeybee (Apis mellifera) has been used with great success in a variety of behavioral studies. The lack of genomic tools in this species has, however, hampered efforts to provide genome-based explanations for behavioral data. We have combined the power of DNA arrays and the availability of distinct behavioral stages in honeybees to explore the dynamics of gene expression during adult development in this insect. In addition, we used caffeine treatment, a procedure that accelerates learning abilities in honeybees, to examine changes in gene expression underlying drug-induced behavioral modifications. RESULTS: Spotted microarrays containing several thousand cDNAs were interrogated with RNAs extracted from newly emerged worker bees, experienced foragers and caffeine-treated bees. Thirty-six differentially expressed cDNAs were verified by northern blot hybridization and characterized in silico by sequencing and database searches. Experienced foragers overexpressed royal jelly proteins, a putative imaginal disc growth factor, a transcriptional regulator (Stck) and several enzymes, including alpha-glucosidases, aminopeptidases and glucose dehydrogenase. Naive workers showed increased expression of members of the SPARC and lectin families, heat-shock cognate proteins and several proteins related to RNA translation and mitochondrial function. A number of novel genes overexpressed in both naive and experienced bees, and genes induced by caffeine, have also been identified. CONCLUSIONS: We have shown the usefulness of this transcriptome-based approach for gene discovery, in particular in the context of the efficacy of drug treatment, in a model organism in which routine genetic techniques cannot be applied easily.

Animals↗