Retraction: Effect of controlled and uncontrolled cooling rate on motility parameters of cryopreserved ram spermatozoa

ABSTRACT: Retraction This article [1] has been retracted at the request of the Editor. Although the authors withdrew their submission in order to publish elsewhere, the article was subsequently transmitted to the journal's production department which resulted in it being published in error.     

Serotonin regulates C. elegans fat and feeding through independent molecular mechanisms

We investigated serotonin signaling in C. elegans as a paradigm for neural regulation of energy balance and found that serotonergic regulation of fat is molecularly distinct from feeding regulation. Serotonergic feeding regulation is mediated by receptors whose functions are not required for fat regulation. Serotonergic fat regulation is dependent on a neurally expressed channel and a G protein-coupled receptor that initiate signaling cascades that ultimately promote lipid breakdown at peripheral sites of fat storage. In turn, intermediates of lipid metabolism generated in the periphery modulate feeding behavior. These findings suggest that, as in mammals, C. elegans feeding behavior is regulated by extrinsic and intrinsic cues. Moreover, obesity and thinness are not solely determined by feeding behavior. Rather, feeding behavior and fat metabolism are coordinated but independent responses of the nervous system to the perception of nutrient availability.     

Cytochemical localization of calcium and Ca2+,Mg2(+)-adenosine triphosphatase in colchicine-altered rat incisor ameloblasts

Colchicine is known to affect secretory, transport, and degradative functions of ameloblasts. The effects of colchicine on membrane-associated calcium and Ca2+,Mg2(+)-ATPase in secretory and maturation ameloblasts were investigated cytochemically. The pyroantimonate (PPA) method was used for localizing calcium and a modified Wachstein-Meisel medium was used to localize Ca2+,Mg2(+)-ATPase. Sections representing secretory and early maturation stages were examined by transmission electron microscopy. Morphological changes induced by colchicine included dislocated organelles and other well-established reactions to such anti-microtubule drugs. Calcium pyroantimonate (Ca-PA) deposits in most ameloblast types were markedly reduced, with the greater reduction occurring in those cells more severely altered morphologically. However, the cell membranes of both control and experimental smooth-ended maturation ameloblasts were essentially devoid of Ca-PA. The normal distribution and intensity of Ca2+,Mg2(+)-ATPase was not affected by colchicine. Because the observed reduction of membrane-associated calcium is apparently not mediated by Ca2+,Mg2(+)-ATPase in this case, other aspects of the calcium regulating system of ameloblasts are apparently targeted by colchicine.     

The bovine papillomavirus type 4 E8 protein binds to ductin and causes loss of gap junctional intercellular communication in primary fibroblasts.

The E8 open reading frame of bovine papillomavirus type 4 encodes a small hydrophobic polypeptide which contributes to cell transformation by conferring anchorage-independent growth. Using an in vitro translation system, we show that the E8 polypeptide binds to ductin, the 16-kDa proteolipid that forms transmembrane channels in both gap junctions and vacuolar H+-ATPase. This association is not due to nonspecific hydrophobic interactions. PPA1, a Saccharomyces cerevisiae polypeptide homologous (with 25% identity) to ductin, does not complex with E8. Furthermore, E5B, structurally similar to E8 but with no transforming activity, does not form a complex with ductin. Primary bovine fibroblasts expressing E8 show a loss of gap junctional intercellular communication, and it is suggested that this results from the interaction between E8 and ductin.     

Temporal relationship between genetic and warning signal variation in the aposematic wood tiger moth (Parasemia plantaginis)

Many plants and animals advertise unpalatability through warning signals in the form of colour and shape. Variation in warning signals within local populations is not expected because they are subject to directional selection. However, mounting evidence of warning signal variation within local populations suggests that other selective forces may be acting. Moreover, different selective pressures may act on the individual components of a warning signal. At present, we have a limited understanding about how multiple selection processes operate simultaneously on warning signal components, and even less about their temporal and spatial dynamics. Here, we examined temporal variation of several wing warning signal components (colour, UV‐reflectance, signal size and pattern) of two co‐occurring colour morphs of the aposematic wood tiger moth (Parasemia plantaginis). Sampling was carried out in four geographical regions over three consecutive years. We also evaluated each morph's temporal genetic structure by analysing mitochondrial sequence data and nuclear microsatellite markers. Our results revealed temporal differences between the morphs for most signal components measured. Moreover, variation occurred differently in the fore‐ and hindwings. We found no differences in the genetic structure between the morphs within years and regions, suggesting single local populations. However, local genetic structure fluctuated temporally. Negative correlations were found between variation produced by neutrally evolving genetic markers and those of the different signal components, indicating a non‐neutral evolution for most warning signal components. Taken together, our results suggest that differential selection on warning signal components and fluctuating population structure can be one explanation for the maintenance of warning signal variation in this aposematic species.