Astaxanthin in the blue oceanic barnacleLepas fascicularis

Zusammenfassung Die blaue Farbe der ozeanischen Cirripedien,Lepas fascicularis, wird als Chromoproteid mit Astaxanthin als Carotinoidkomponente identifiziert.

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These researches are among those supported by Research Grant No. GB-2312 to the senior author from the National Science Foundation. We are indebted also to Dr.W. A. Newman for his help and information concerning the biology of this barnacle.     

A physical map of the mouse genome

A physical map of a genome is an essential guide for navigation, allowing the location of any gene or other landmark in the chromosomal DNA. We have constructed a physical map of the mouse genome that contains 296 contigs of overlapping bacterial clones and 16,992 unique markers. The mouse contigs were aligned to the human genome sequence on the basis of 51,486 homology matches, thus enabling use of the conserved synteny (correspondence between chromosome blocks) of the two genomes to accelerate construction of the mouse map. The map provides a framework for assembly of whole-genome shotgun sequence data, and a tile path of clones for generation of the reference sequence. Definition of the human-mouse alignment at this level of resolution enables identification of a mouse clone that corresponds to almost any position in the human genome. The human sequence may be used to facilitate construction of other mammalian genome maps using the same strategy.     

De novo pyrimidine biosynthesis is required for virulence of Toxoplasma gondii

Toxoplasma gondii is a ubiquitous protozoan parasite that is responsible for severe congenital birth defects and fatal toxoplasmic encephalitis in immunocompromized people. Fundamental aspects of obligate intracellular replication and pathogenesis are only now beginning to emerge for protozoan parasites. T. gondii has a fragmented pathway for salvaging pyrimidine nucleobases derived from the parasite or host cell, and this limited pyrimidine salvage capacity is funnelled exclusively through uracil phosphoribosyltransferase. Disrupting the function of this enzyme does not affect the growth of T. gondii tachyzoites, which suggests that the de novo pyrimidine biosynthesis pathway may be necessary for growth. We have examined the virulence of T. gondii mutants that lack carbamoyl phosphate synthetase II (uracil auxotrophs) to determine whether de novo pyrimidine biosynthesis is required in vivo. Here we show that T. gondii uracil auxotrophs are completely avirulent not only in immune-competent BALB/c mice but also in mice that lack interferon-gamma. A single injection of the uracil auxotroph into BALB/c mice induces long-term protective immunity to toxoplasmosis. Our findings indicate the significance of the de novo pyrimidine biosynthesis pathway for the virulence of parasitic protozoa, and suggest routes for developing vaccines and chemotherapy.     

Three types of neuronal calcium channel with different calcium agonist sensitivity

How many types of calcium channels exist in neurones? This question is fundamental to understanding how calcium entry contributes to diverse neuronal functions such as transmitter release, neurite extension, spike initiation and rhythmic firing. There is considerable evidence for the presence of more than one type of Ca conductance in neurones and other cells. However, little is known about single-channel properties of diverse neuronal Ca channels, or their responsiveness to dihydropyridines, compounds widely used as labels in Ca channel purification. Here we report evidence for the coexistence of three types of Ca channel in sensory neurones of the chick dorsal root ganglion. In addition to a large conductance channel that contributes long-lasting current at strong depolarizations (L), and a relatively tiny conductance that underlies a transient current activated at weak depolarizations (T), we find a third type of unitary activity (N) that is neither T nor L. N-type Ca channels require strongly negative potentials for complete removal of inactivation (unlike L) and strong depolarizations for activation (unlike T). The dihydropyridine Ca agonist Bay K 8644 strongly increases the opening probability of L-, but not T- or N-type channels.     

Mutations in the facilitative glucose transporter GLUT10 alter angiogenesis and cause arterial tortuosity syndrome

Arterial tortuosity syndrome (ATS) is an autosomal recessive disorder characterized by tortuosity, elongation, stenosis and aneurysm formation in the major arteries owing to disruption of elastic fibers in the medial layer of the arterial wall. Previously, we used homozygosity mapping to map a candidate locus in a 4.1-Mb region on chromosome 20q13.1 (ref. 2). Here, we narrowed the candidate region to 1.2 Mb containing seven genes. Mutations in one of these genes, SLC2A10, encoding the facilitative glucose transporter GLUT10, were identified in six ATS families. GLUT10 deficiency is associated with upregulation of the TGFbeta pathway in the arterial wall, a finding also observed in Loeys-Dietz syndrome, in which aortic aneurysms associate with arterial tortuosity. The identification of a glucose transporter gene responsible for altered arterial morphogenesis is notable in light of the previously suggested link between GLUT10 and type 2 diabetes. Our data could provide new insight on the mechanisms causing microangiopathic changes associated with diabetes and suggest that therapeutic compounds intervening with TGFbeta signaling represent a new treatment strategy.