Herpes simplex virus type 1 portal protein UL6 interacts with the putative terminase subunits UL15 and UL28

The herpes simplex virus type 1 (HSV-1) UL6, UL15, and UL28 proteins are essential for cleavage of replicated concatemeric viral DNA into unit length genomes and their packaging into a preformed icosahedral capsid known as the procapsid. The capsid-associated UL6 DNA-packaging protein is located at a single vertex and is thought to form the portal through which the genome enters the procapsid. The UL15 protein interacts with the UL28 protein, and both are strong candidates for subunits of the viral terminase, a key component of the molecular motor that drives the DNA into the capsid. To investigate the association of the UL6 protein with the UL15 and UL28 proteins, the three proteins were produced in large amounts in insect cells with the baculovirus expression system. Interactions between UL6 and UL28 and between UL6 and UL15 were identified by an immunoprecipitation assay. These results were confirmed by transiently expressing wild-type and mutant proteins in mammalian cells and monitoring their distribution by immunofluorescence. In cells expressing the single proteins, UL6 and UL15 were concentrated in the nuclei whereas UL28 was found in the cytoplasm. When the UL6 and UL28 proteins were coexpressed, UL28 was redistributed to the nuclei, where it colocalized with UL6. In cells producing either of two cytoplasmic UL6 mutant proteins and a functional epitope-tagged form of UL15, the UL15 protein was concentrated with the mutant UL6 protein in the cytoplasm. These observed interactions of UL6 with UL15 and UL28 are likely to be of major importance in establishing a functional DNA-packaging complex at the portal vertex of the HSV-1 capsid.     

Zebrafish frizzled7b is expressed in prechordal mesoderm,brain and paraxial mesoderm

Frizzled (fz) genes encode receptors for the Wnt signaling pathway. We describe a novel fz gene, zebrafish fz7b. Maternal fz7b mRNA is detectable by RT-PCR. Embryonic fz7b is widely distributed in early epiboly stage embryos. By shield stage, expression appears enriched around the blastoderm margin. During epiboly, expression becomes restricted to the prechordal plate, presumptive midbrain and hindbrain and paraxial mesoderm. As somites form, labeling is briefly present in a segmental pattern. By mid-somitogensis, expression is particularly enriched in the forebrain, the forebrain-midbrain boundary, and the anterior hindbrain, but appears at lower levels throughout much of the rostral CNS. The CNS expression is at ventral and medial positions. The paraxial mesoderm expression becomes restricted to the tailbud. This pattern continues through 26 h. At 48 h, weak expression is seen in the pharyngeal arches and developing fin.     

Expression of biotin-binding proteins,avidin and streptavidin,in plant tissues using plant vacuolar targeting sequences

Tobacco plants have been developed which constitutively express high levels of the biotin-binding proteins, avidin and streptavidin. These plants were phenotypically normal and produced fertile pollen and seeds. The transgene was expressed and its product located in the vacuoles of most cell types in the plants. Targeting was achieved by use of N-terminal vacuolar targeting sequences derived from potato proteinase inhibitors which are known to target constitutively to vacuoles in potato tubers and, under wound-induction, in tomato leaves. Avidin was located in protein body-like structures within the vacuole and transgene protein levels remained relatively constant throughout the lifetime of the leaf. We describe two chimeric constructs with similar levels of expression. One comprised a potato proteinase inhibitor I signal peptide cDNA sequence attached to an avidin cDNA and the second a potato proteinase inhibitor II signal peptide genomic sequence (including an intron) attached to a core streptavidin synthetic sequence. We were unable to regenerate plants when transformation used constructs lacking the targeting sequences. The highest levels observed (up to 1.5% of total leaf protein) confirm the vacuole as the organelle of choice for stable storage of plant-toxic transgene products. The efficient targeting of these proteins did not result in any measured changes in plant biotinmetabolism.     

Enhanced kinetic extraction of parvovirus B19 structural proteins

Recombinant structural proteins (VP1 and VP2) of the human parvovirus B19 have been expressed simultaneously using the baculovirus expression system to form virus-like particles (VLPs) that have potential use as vaccines. In this study, we report optimization of extraction conditions to recover these VLPs from cell paste. Under hypotonic conditions with neutral pH these VLPs were poorly extracted (up to 3% extraction). Addition of reducing agents, detergents, salts, and sonication did not improve the extractability. While screening for conditions to improve the extractability of the VLPs, we discovered that a combination of higher pH and elevated processing temperature significantly increased the extraction. Whereas increasing pH alone increased extractability from 3% to 6% (pH increased from 8.0 to 9.5), the effect of elevated temperature was much more substantial. At 50 degrees C, we observed the extraction to be more than fivefold higher than that at room temperature (up to 25% extracted at pH 9.0). The kinetics of extraction at elevated temperatures showed a rapid initial rate of extraction (on the order of minutes) followed by a plateau. In addition, we compared the extraction of VP1 expressed alone. VP1 expressed alone is incapable of forming VLPs. We observed that non-VLP VP1 was easily extractable (up to 60% extracted) under conditions in which the VP1 + VP2 VLPs were not extractable. From these studies we conclude that parvovirus B19 structural proteins expressed to form VLPs have a hindered extractability as compared with non-VLP protein. This hindrance to extraction can be significantly reduced by processing at elevated temperatures and an increased pH, possibly due to the enhanced rates of solubilization and diffusion.     

Birth in marsupials

Birth is an event that allows the relatively immature marsupial to move from the internal environment of the uterus to the external environment of the pouch. The newborn marsupial passes down from the uterus to the urogenital sinus and then makes its way to the pouch and attaches to the teat at a very early stage of development. From the studies available, there appear to be three methods used by the newborn to move from the uterus to the pouch. In marsupials with a forward pouch such as the red kangaroo, tammar wallaby and the brushtail possum, the mother positions her urogenital sinus below the pouch and the newborn climb upward towards the pouch. The young climb with a swimming motion, moving the head from side-to-side and use the forearms in alternate strokes. In the bandicoot with a backward facing pouch, the mother positions the urogenital sinus above the pouch and the young slither down into the pouch. The young do not have a definite crawl, as seen with the macropodids and possum. The third method of birth has been observed in the marsupials without a definite pouch that have a mammary region that develops as the young grow in size. This type of pouch is observed in the dasyurids. The mother was noted to stand on four legs with her hips raised so that the urogenital sinus was above the pouch and the newborn young crawled downwards from the sinus to the pouch. In all species, birth was completed in 2–4 min.