Immunoquantitation of some cytochrome P-450 isozymes in liver microsomes from streptozotocin-diabetic rats

Streptozotocin-diabetes in rats leads to a decrease of cytochrome P-450 UT-A (the major form in control rats) and an increase of cytochrome P-450 PB-B (the major one induced by phenobarbital treatment) in liver microsomes. The increased benzphetamine-N-demethylase activity can be related to the induction of cytochrome P-450 PB-B.     

Functional coordination of intraflagellar transport motors

Cilia have diverse roles in motility and sensory reception, and defects in cilia function contribute to ciliary diseases such as Bardet-Biedl syndrome (BBS). Intraflagellar transport (IFT) motors assemble and maintain cilia by transporting ciliary precursors, bound to protein complexes called IFT particles, from the base of the cilium to their site of incorporation at the distal tip. In Caenorhabditis elegans, this is accomplished by two IFT motors, kinesin-II and osmotic avoidance defective (OSM)-3 kinesin, which cooperate to form two sequential anterograde IFT pathways that build distinct parts of cilia. By observing the movement of fluorescent IFT motors and IFT particles along the cilia of numerous ciliary mutants, we identified three genes whose protein products mediate the functional coordination of these motors. The BBS proteins BBS-7 and BBS-8 are required to stabilize complexes of IFT particles containing both of the IFT motors, because IFT particles in bbs-7 and bbs-8 mutants break down into two subcomplexes, IFT-A and IFT-B, which are moved separately by kinesin-II and OSM-3 kinesin, respectively. A conserved ciliary protein, DYF-1, is specifically required for OSM-3 kinesin to dock onto and move IFT particles, because OSM-3 kinesin is inactive and intact IFT particles are moved by kinesin-II alone in dyf-1 mutants. These findings implicate BBS ciliary disease proteins and an OSM-3 kinesin activator in the formation of two IFT pathways that build functional cilia.     

Disruption of Bardet-Biedl syndrome ciliary proteins perturbs planar cell polarity in vertebrates

The evolutionarily conserved planar cell polarity (PCP) pathway (or noncanonical Wnt pathway) drives several important cellular processes, including epithelial cell polarization, cell migration and mitotic spindle orientation. In vertebrates, PCP genes have a vital role in polarized convergent extension movements during gastrulation and neurulation. Here we show that mice with mutations in genes involved in Bardet-Biedl syndrome (BBS), a disorder associated with ciliary dysfunction, share phenotypes with PCP mutants including open eyelids, neural tube defects and disrupted cochlear stereociliary bundles. Furthermore, we identify genetic interactions between BBS genes and a PCP gene in both mouse (Ltap, also called Vangl2) and zebrafish (vangl2). In zebrafish, the augmented phenotype results from enhanced defective convergent extension movements. We also show that Vangl2 localizes to the basal body and axoneme of ciliated cells, a pattern reminiscent of that of the BBS proteins. These data suggest that cilia are intrinsically involved in PCP processes.     

低碳锰钢中周期性带状组织

用扫描电镜和电子探针研究了低碳锰钢中的周期性带状组织，结果表明，在全部研究用钢中，钢锭经热轧后均出现这种组织，其严重程度随钢的成分而异，并随坯带加工顺序而增加，带状组织与锰的显微偏析等因素有关，适当的调整碳锰以及形成模跨铁素体带的转变产物可降低带状组织的严重程度。     

Upregulation of rat P23 (a member of the YjgF protein family) by fasting, glucose diet and fatty acid feeding

In a previous study, we identified and purified a 99-amino-acid rat liver-kidney perchloric-acid-soluble 23-kDa protein (P23) which displays 30% identity with a highly conserved domain of heat shock proteins (HSPs), as well as an AT-rich 3 untranslated region, which has also been described to play a role in H70 mRNA life span and protein expression. An identical perchloric-acid-soluble protein inhibiting protein synthesis in a rabbit reticulocyte lysate system was also found 2 years later by another group. More recently, the novel, the YjgF, protein family has been described, comprising, 24 full-length homologues, including P23, highly conserved through evolution, and consisting of approximately 130 residues each and sharing a common ternary structure. Independent studies from different laboratories have provided various hypothetical functions for each of these proteins. The high degree of evolutionary conservation may suggest that these proteins play an important role in cellular regulation. Although the function of none of these proteins is known precisely, we present experimental evidence which, combined with the relationship to glucose-regulating protein revealed here, and the relationship to fatty-acid-binding protein revealed by others, allow us to propose a role for P23. In rat liver, P23 expression is developmentally regulated and modulated by dietary glucose, and its mRNA is induced by starvation, in the presence of fatty-acids and in 3-MeDAB-induced hepatomas. The mRNA encoding mouse liver P23 is also hormonally modulated in a mouse line AT1F8. These data indicate that P23 protein might be a key controller of intermediary metabolism during fasting.Received 7 June 2003; received after revision 8 September 2004; accepted 10 October 2004     

The Bardet-Biedl protein BBS4 targets cargo to the pericentriolar region and is required for microtubule anchoring and cell cycle progression

BBS4 is one of several proteins that cause Bardet-Biedl syndrome (BBS), a multisystemic disorder of genetic and clinical complexity. Here we show that BBS4 localizes to the centriolar satellites of centrosomes and basal bodies of primary cilia, where it functions as an adaptor of the p150(glued) subunit of the dynein transport machinery to recruit PCM1 (pericentriolar material 1 protein) and its associated cargo to the satellites. Silencing of BBS4 induces PCM1 mislocalization and concomitant deanchoring of centrosomal microtubules, arrest in cell division and apoptotic cell death. Expression of two truncated forms of BBS4 that are similar to those found in some individuals with BBS had a similar effect on PCM1 and microtubules. Our findings indicate that defective targeting or anchoring of pericentriolar proteins and microtubule disorganization contribute to the BBS phenotype and provide new insights into possible causes of familial obesity, diabetes and retinal degeneration.     

Bardet-Biedl syndrome: an emerging pathomechanism of intracellular transport

From a handful of uncloned genetic loci 6 years ago, great strides have been made in understanding the genetic and molecular aetiology of Bardet-Biedl syndrome (BBS), a rare pleiotropic disorder characterised by a multitude of symptoms, including obesity, retinal degeneration and cystic kidneys. Presently, 11 BBS genes have been cloned, with the likelihood that yet more BBS genes remain undiscovered. In 2003, a major breakthrough was made when it was shown that BBS is likely caused by defects in basal bodies and/or primary cilia. Since then, studies in numerous animal models of BBS have corroborated the initial findings and, in addition, have further refined the specific functions of BBS proteins. These include roles in establishing planar cell polarity (noncanonical Wnt signaling) in mice and zebrafish, modulating intraflagellar transport and lipid homeostasis in worms, and regulating intracellular trafficking and centrosomal functions in zebrafish and human tissue culture cells. From these discoveries, a common theme has emerged, namely that the primary function of BBS proteins may be to mediate and regulate microtubule-based intracellular transport processes. Received 20 April 2006; received after revision 30 May 2006; accepted 15 June 2006