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Abstract: Background: Myosin-IIB is a non-muscle isoform in the brain with increased expression in the brains of diabetic rats. Chronic hyperglycemia caused by diabetes can impair learning and memory. Oral hypoglycemic agents such as glibenclamide have been used to control hyperglycemia. We report changes in the expression and distribution of myosin-IIB in the frontal cortex and hippocampus of diabetic rats treated with glibenclamide. Methods: The brains were removed after 43days of treatment with glibenclamide (6mg/kg bw orally), homogenized and analyzed by Western blotting, qRT-PCR and immunohistochemistry. Results: Myosin-IIB expression increased in the brains of diabetic rats. However, protein expression returned to control levels when treated with glibenclamide. In addition, the expression of MYH10 gene encoding non-muscle myosin heavy chain-B decreased in diabetic rats treated with glibenclamide. Moreover, we found weak myosin-IIB labeling in the hippocampus and frontal cortex of rats treated with glibenclamide. Therefore, the expression of myosin-IIB is affected by diabetes mellitus and may be modulated by glibenclamide treatment in rats. Structural changes in the hippocampus and prefrontal cortex are reversible, and glibenclamide treatment may reduce the patho-physiological changes in the brain. Conclusions: Our findings can contribute to the understanding of the regulation of myosins in the brains of diabetic rats. [Copyright &y& Elsevier]

Abstract: Honey bees have brain structures with specialized and developed systems of communication that account for memory, learning capacity and behavioral organization with a set of genes homologous to vertebrate genes. Many microtubule- and actin-based molecular motors are involved in axonal/dendritic transport. Myosin-Va is present in the honey bee Apis mellifera nervous system of the larvae and adult castes and subcastes. DYNLL1/LC8 and myosin-IIb, -VI and -IXb have also been detected in the adult brain. SNARE proteins, such as CaMKII, clathrin, syntaxin, SNAP25, munc18, synaptophysin and synaptotagmin, are also expressed in the honey bee brain. Honey bee myosin-Va displayed ATP-dependent solubility and was associated with DYNLL1/LC8 and SNARE proteins in the membrane vesicle-enriched fraction. Myosin-Va expression was also decreased after the intracerebral injection of melittin and NMDA. The immunolocalization of myosin-Va and -IV, DYNLL1/LC8, and synaptophysin in mushroom bodies, and optical and antennal lobes was compared with the brain morphology based on Neo-Timm histochemistry and revealed a distinct and punctate distribution. This result suggested that the pattern of localization is associated with neuron function. Therefore, our data indicated that the roles of myosins, DYNLL1/LC8, and SNARE proteins in the nervous and visual systems of honey bees should be further studied under different developmental, caste and behavioral conditions. [Copyright &y& Elsevier]

Abstract: The Ca2+/calmodulin complex interacts with and regulates various enzymes and target proteins known as calmodulin-binding proteins (CaMBPs). This group of proteins includes molecular motors such as myosins. In this study, we show that non-muscle myosin-IIB is overexpressed in the brains of diabetic rats. We isolated CaMBPs from the brains of non-diabetic rats and rats with streptozotocin-induced diabetes and purified them by immobilized-calmodulin affinity chromatography. The proteins were eluted with EGTA and urea, separated by SDS-PAGE, digested and submitted to peptide mass fingerprinting analysis. Thirteen intense bands were found in both types of brains, two were found exclusively in non-diabetic brains and four were found exclusively in diabetic brains. A large fraction of the eluted proteins contained putative IQ motifs or calmodulin-binding sites. The results of the myosin-IIB affinity chromatography elution, western blot and RT-PCR analyses suggest that myosin-IIB protein and mRNA are expressed at high levels in diabetic brains. This is the first study that has demonstrated differential expression of CaMBPs in diabetic and non-diabetic brain tissue through a comparative proteomic analysis, and it opens up a new approach to studying the relationship between the expression of myosins in the brain, hyperglycemia and intracellular calcium regulation. [Copyright &y& Elsevier]

The presence of myosin and dynein in the ovaries of both Apis mellifera and Scaptotrigona postica was investigated in extracts and in histological sections. In the ovary extracts, motor proteins, myosins V, VI and dynein were detected by Western blot. In histological sections, they were detected by immunocytochemistry, using a mouse monoclonal antibody against the intermediary chain of dynein and a rabbit polyclonal antibody against the myosin V head domain. The myosin VI tail domain was recognized by a pig polyclonal antibody. The results show that these molecular motors are expressed in the ovaries of both bee species with few differences in location and intensity, in regions where movement of substances is expected during oogenesis. The fact that antibodies against vertebrate proteins recognize proteins of bee species indicates that the specific epitopes are evolutionarily well preserved. [ABSTRACT FROM AUTHOR]