蜜蜂蜂王与工蜂级型分化研究进展

蜜蜂ApismekiferaL .是典型的社会性昆虫 ,蜂王和工蜂都是由受精卵发育而来的二倍体成蜂 ,但是在形态、生理、行为等方面有明显的差异 ,属于不同的级型。蜂王和工蜂的级型分化的关键时期发生在幼虫的 4龄末至 5龄止。分化是由分化基因调控的 ,幼虫期食物的质和量是分化的外部决定因子。JH对两级型中卵巢的分化有非常重要的调控作用。蜜蜂脑或其它组织中可能有分泌调控CA的咽侧体调节激素 ,它们通过对CA中JH的合成和分泌的调控而参与了分化的调控。章鱼胺等生物胺也参与了分化调控过程。     

Expression profiles during honeybee caste determination

Background

Depending on their larval environment, female honeybees develop into either queens or workers. As in other polyphenisms, this developmental switch depends not on genomic differences between queens and workers but on the differential expression of entire suites of genes involved with larval fate. As such, this and other polyphenic systems can provide a novel tool for understanding how genomes and environmental conditions interact to produce different developmental trajectories. Here we use gene-expression profiles during honeybee caste determination to present the first genomic view of polyphenic development.

Results

Larvae raised as queens or workers differed greatly in their gene-expression patterns. Workers remained more faithful than queens to the expression profiles of younger, bipotential, larvae. Queens appeared to both downregulate many of the genes expressed by bipotential larvae and turn on a distinct set of caste-related genes. Queens overexpressed several metabolic enzymes, workers showed increased expression of a member of the cytochrome P450 family, hexameric storage proteins and dihydrodiol dehydrogenase, and young larvae overexpressed two putative heat-shock proteins (70 and 90 kDa), and several proteins related to RNA processing and translation.

Conclusions

Large differences in gene expression between queens and workers indicate that social insect castes have faced strong directional selection pressures. Overexpression of metabolic enzymes by queen-destined larvae appears to reflect the enhanced growth rate of queens during late larval development. Many of the differently expressed genes we identified have been tied to metabolic rates and cellular responses to hormones, a result consistent with known physiological differences between queen and worker larvae.     

Expression profiles during honeybee caste determination

Background  

Depending on their larval environment, female honeybees develop into either queens or workers. As in other polyphenisms, this developmental switch depends not on genomic differences between queens and workers but on the differential expression of entire suites of genes involved with larval fate. As such, this and other polyphenic systems can provide a novel tool for understanding how genomes and environmental conditions interact to produce different developmental trajectories. Here we use gene-expression profiles during honeybee caste determination to present the first genomic view of polyphenic development.     

Differential protein expression in honeybee (Apis mellifera L.) larvae: underlying caste differentiation

Honeybee (Apis mellifera) exhibits divisions in both morphology and reproduction. The queen is larger in size and fully developed sexually, while the worker bees are smaller in size and nearly infertile. To better understand the specific time and underlying molecular mechanisms of caste differentiation, the proteomic profiles of larvae intended to grow into queen and worker castes were compared at 72 and 120 hours using two dimensional electrophoresis (2-DE), network, enrichment and quantitative PCR analysis. There were significant differences in protein expression between the two larvae castes at 72 and 120 hours, suggesting the queen and the worker larvae have already decided their fate before 72 hours. Specifically, at 72 hours, queen intended larvae over-expressed transketolase, aldehyde reductase, and enolase proteins which are involved in carbohydrate metabolism and energy production, imaginal disc growth factor 4 which is a developmental related protein, long-chain-fatty-acid CoA ligase and proteasome subunit alpha type 5 which metabolize fatty and amino acids, while worker intended larvae over-expressed ATP synthase beta subunit, aldehyde dehydrogenase, thioredoxin peroxidase 1 and peroxiredoxin 2540, lethal (2) 37 and 14-3-3 protein epsilon, fatty acid binding protein, and translational controlled tumor protein. This differential protein expression between the two caste intended larvae was more pronounced at 120 hours, with particular significant differences in proteins associated with carbohydrate metabolism and energy production. Functional enrichment analysis suggests that carbohydrate metabolism and energy production and anti-oxidation proteins play major roles in the formation of caste divergence. The constructed network and validated gene expression identified target proteins for further functional study. This new finding is in contrast to the existing notion that 72 hour old larvae has bipotential and can develop into either queen or worker based on epigenetics and can help us to gain new insight into the time of departure as well as caste trajectory influencing elements at the molecular level.     

基因差异性表达与衰老

微细胞融合实验表明：人的第１、４、６、７号染色体以及Ｘ染色体上存在衰老基因;基因差异性表达研究方法显示：衰老细胞具有特异性表达或高表达的基因。提示细胞衰老是个主动过程,可能与包括衰老基因在内一系列基因激活有关。     

Worker caste determination in the army ant Eciton burchellii

Elaborate division of labour has contributed significantly to the ecological success of social insects. Division of labour is achieved either by behavioural task specialization or by morphological specialization of colony members. In physical caste systems, the diet and rearing environment of developing larvae is known to determine the phenotype of adult individuals, but recent studies have shown that genetic components also contribute to the determination of worker caste. One of the most extreme cases of worker caste differentiation occurs in the army ant genus Eciton, where queens mate with many males and colonies are therefore composed of numerous full-sister subfamilies. This high intracolonial genetic diversity, in combination with the extreme caste polymorphism, provides an excellent test system for studying the extent to which caste determination is genetically controlled. Here we show that genetic effects contribute significantly to worker caste fate in Eciton burchellii. We conclude that the combination of polyandry and genetic variation for caste determination may have facilitated the evolution of worker caste diversity in some lineages of social insects.     

Differential regulation drives plasticity in sex determination gene networks

Background  

Sex determination networks evolve rapidly and have been studied intensely across many species, particularly in insects, thus presenting good models to study the evolutionary plasticity of gene networks.     

Differential gene expression in the developing mouse ureter

In many instances, kidney dysgenesis results as a secondary consequence to defects in the development of the ureter. Through the use of mouse genetics a number of genes associated with such malformations have been identified, however, the cause of many other abnormalities remain unknown. In order to identify novel genes involved in ureter development we compared gene expression in embryonic day (E) 12.5, E15.5 and postnatal day (P) 75 ureters using the Compugen mouse long oligo microarrays. A total of 248 genes were dynamically upregulated and 208 downregulated between E12.5 and P75. At E12.5, when the mouse ureter is comprised of a simple cuboidal epithelium surrounded by ureteric mesenchyme, genes previously reported to be expressed in the ureteric mesenchyme, foxC1 and foxC2 were upregulated. By E15.5 the epithelial layer develops into urothelium, impermeable to urine, and smooth muscle develops for the peristaltic movement of urine towards the bladder. The development of these two cell types coincided with the upregulation of UPIIIa, RAB27b and PPARgamma reported to be expressed in the urothelium, and several muscle genes, Acta1, Tnnt2, Myocd, and Tpm2. In situ hybridization identified several novel genes with spatial expression within the smooth muscle, Acta1; ureteric mesenchyme and smooth muscle, Thbs2 and Col5a2; and urothelium, Kcnj8 and Adh1. This study marks the first known report defining global gene expression of the developing mouse ureter and will provide insight into the molecular mechanisms underlying kidney and lower urinary tract malformations.     

Differential gene expression in the jellyfish Aurelia aurita

The body of Aurelia aurita, as well as other diploblasts, consists of two epithelial layers: ectodermal and gastral epithelium. These two tissues are separated by mesoglea, or extracellular matrix. In most coelenterates mesoglea is acellular. In A. aurita mesogleal cells are scattered in mesoglea. Differential display PCR was used to compare mRNA pools from ectodermal epithelium, gastral epithelium and mesoglea. 4 novel gene fragments were cloned and sequenced. According to RTPCR results, one of these fragments is differentially expressed in the ectodermal epithelium.     

Differential expression of odorant-binding proteins in the mandibular glands of the honey bee according to caste and age

Odorant-binding proteins (OBPs) and chemosensory proteins (CSPs) mediate both perception and release of chemical stimuli in insects. The genome of the honey bee contains 21 genes encoding OBPs and 6 encoding CSPs. Using a proteomic approach, we have investigated the expression of OBPs and CSPs in the mandibular glands of adult honey bees in relation to caste and age. OBP13 is mostly expressed in young individuals and in virgin queens, while OBP21 is abundant in older bees and is prevalent in mated queens. OBP14, which had been found in larvae, is produced in hive workers' glands. Quite unexpectedly, the mandibular glands of drones also contain OBPs, mainly OBP18 and OBP21. We have expressed three of the most represented OBPs and studied their binding properties. OBP13 binds with good specificity oleic acid and some structurally related compounds, OBP14 is better tuned to monoterpenoid structures, while OBP21 binds the main components of queen mandibular pheromone as well as farnesol, a compound used as a trail pheromone in the honey bee and other hymenopterans. The high expression of different OBPs in the mandibular glands suggests that such proteins could be involved in solubilization and release of semiochemicals.     

Maternal effect on female caste determination in a social insect

Caste differentiation and division of labor are the hallmarks of social insect colonies [1, 2]. The current dogma for female caste differentiation is that female eggs are totipotent, with morphological and physiological differences between queens and workers stemming from a developmental switch during the larval stage controlled by nutritional and other environmental factors (e.g., [3-8]). In this study, we tested whether maternal effects influence caste differentiation in Pogonomyrmex harvester ants. By conducting crossfostering experiments we identified two key factors in the process of caste determination. New queens were produced only from eggs laid by queens exposed to cold. Moreover, there was a strong age effect, with development into queens occurring only in eggs laid by queens that were at least two years old. Biochemical analyses further revealed that the level of ecdysteroids was significantly lower in eggs developing into queens than workers. By contrast, we found no significant effect of colony size or worker exposure to cold, suggesting that the trigger for caste differentiation may be independent of the quantity and quality of resources provided to larvae. Altogether these data demonstrate that the developmental fate of female brood is strongly influenced by maternal effects in ants of the genus Pogonomyrmex.     

Social transmission of nectar-robbing behaviour in bumble-bees

Social transmission of acquired foraging techniques is rarely considered outside of a vertebrate context. Here, however, we show that nectar robbing by bumble-bees (Bombus terrestris)-an invertebrate behaviour of considerable ecological significance-has the potential to spread through a population at the accelerated rates typical of social transmission. Nectar robbing occurs when individuals either bite through the base of a flower to 'steal' nectar (primary robbing) or use robbing holes that others have made (secondary robbing). We found that experience of foraging from robbed flowers significantly promoted the development of primary robbing in previously legitimate foragers, thus implying that the acquisition of nectar robbing by one individual will facilitate its adoption in others. Our findings suggest that the positive feedback effects of social transmission may potentially play an ecologically important role in the relationship between plants and pollinators.