The homodimeric kinesin, Kif17, is essential for vertebrate photoreceptor sensory outer segment development

Sensory cilia and intraflagellar transport (IFT), a pathway essential for ciliogenesis, play important roles in embryonic development and cell differentiation. In vertebrate photoreceptors IFT is required for the early development of ciliated sensory outer segments (OS), an elaborate organelle that sequesters the many proteins comprising the phototransduction machinery. As in other cilia and flagella, heterotrimeric members of the kinesin 2 family have been implicated as the anterograde IFT motor in OS. However, in Caenorhabditis elegans, OSM-3, a homodimeric kinesin 2 motor, plays an essential role in some, but not all sensory cilia. Kif17, a vertebrate OSM-3 homologue, is known for its role in dendritic trafficking in neurons, but a function in ciliogenesis has not been determined. We show that in zebrafish Kif17 is widely expressed in the nervous system and retina. In photoreceptors Kif17 co-localizes with IFT proteins within the OS, and co-immunoprecipitates with IFT proteins. Knockdown of Kif17 has little if any effect in early embryogenesis, including the formation of motile sensory cilia in the pronephros. However, OS formation and targeting of the visual pigment protein is severely disrupted. Our analysis shows that Kif17 is essential for photoreceptor OS development, and suggests that Kif17 plays a cell type specific role in vertebrate ciliogenesis.     

High level expression of soybean trypsin inhibitor gene in transgenic tobacco plants failed to confer resistance against damage caused byHelicoverpa armigera

Helicoverpa armigera is a major pest of many tropical crop plants. Soybean trypsin inhibitor (SBTI) was highly effective against the proteolytic activity of gut extract of the insect. SBTI was also inhibitory to insect growth when present in artificial diet. The gene coding for SBTI was cloned from soybean (Glycine max, CVBirsa) and transferred to tobacco plants for constitutive expression. Young larvae ofH. armigera, fed on the leaves of the transgenic tobacco plants expressing high level of SBTI, however, maintained normal growth and development. The results suggest that in certain cases the trypsin inhibitor gene(s) may not be suitable candidates for developing insect resistant transgenic plants.     

Staff Perception on Biomedical or Health Care Waste Management: A Qualitative Study in a Rural Tertiary Care Hospital in India

Background

Health care or biomedical waste, if not managed properly, can be of high risk to the hospital staff, the patients, the community, public health and the environment, especially in low and middle income settings where proper disposal norms are often not followed. Our aim was to explore perceptions of staff of an Indian rural tertiary care teaching hospital on hospital waste management.

Method

A qualitative study was conducted using 10 focus group discussions (FGDs), with different professional groups, cleaning staff, nurses, medical students, doctors and administrators. The FGD guide included the following topics: (i) role of Health Care Waste Management (HCWM) in prevention of health care associated infections, (ii) awareness of and views about HCWM-related guidelines/legislation, (iii) current HCWM practices, (iv) perception and preparedness related to improvements of the current practices, and (v) proper implementation of the available guidelines/legislation. The FGDs were recorded, transcribed verbatim, translated to English (when conducted in Hindi) and analysed using content analysis.

Results

Two themes were identified: Theme (A), ‘Challenges in integration of HCWM in organizational practice,’ with the categories (I) Awareness and views about HCWM, (II) Organizational practices regarding HCWM, and (III) Challenges in Implementation of HCWM; and Theme (B), ‘Interventions to improve HCWM,’ with three categories, (I) Educational and motivational interventions, (II) Organizational culture change, and (III) Policy-related interventions.

Conclusion

A gap between knowledge and actual practice regarding HCWM was highlighted in the perception of the hospital staff. The participants suggested organizational changes, training and monitoring to address this. The information generated is relevant not merely to the microsystem studied but to other institutions in similar settings.     

Proteinase suppression by E-cadherin-mediated cell-cell attachment in premalignant oral keratinocytes

The expression and activity of epithelial proteinases is under stringent control to prevent aberrant hydrolysis of structural proteins and disruption of tissue architecture. E-cadherin-dependent cell-cell adhesion is also important for maintenance of epithelial structural integrity, and loss of E-cadherin expression has been correlated with enhanced invasive potential in multiple tumor models. To address the hypothesis that there is a functional link between E-cadherin and proteinase expression, we have examined the role of E-cadherin in proteinase regulation. By using a calcium switch protocol to manipulate junction assembly, our data demonstrate that initiation of de novo E-cadherin-mediated adhesive contacts suppresses expression of both relative matrix metalloproteinase-9 levels and net urinary-type plasminogen activator activity. E-cadherin-mediated cell-cell adhesion increases both phosphatidylinositol 3'-kinase (PI3-kinase)-dependent AKT phosphorylation and epidermal growth factor receptor-dependent MAPK/ERK activation. Pharmacologic inhibition of the PI3-kinase pathway, but not the epidermal growth factor receptor/MAPK pathway, prevents E-cadherin-mediated suppression of proteinases and delays junction assembly. Moreover, inhibition of junction assembly with a function-blocking anti-E-cadherin antibody stimulates proteinase-dependent Matrigel invasion. As matrix metalloproteinase-9 and urinary-type plasminogen activator potentiate the invasive activity of oral squamous cell carcinoma, these data suggest E-cadherin-mediated signaling through PI3-kinase can regulate the invasive behavior of cells by modulating proteinase secretion.     

Structure of testicular angiotensin-converting enzyme. A segmental mosaic isozyme

The complete amino acid sequence of rabbit testicular angiotensin-converting enzyme has been deduced from the sequence of the corresponding cDNA clone. A protein of the expected molecular weight of 84,000 was translated in vitro from the mRNA encoded by this cDNA. All of the previously determined sequences of seven tryptic peptides from the enzyme are present in the deduced sequence, thus confirming the identity of the protein. From the deduced sequence it appears that the protein contains a signal peptide at the amino terminus and a hydrophobic anchoring domain near the carboxyl terminus. Northern analysis with oligonucleotide probes, whose sequences represented different regions of the cDNA, revealed not only the regions of extensive homology between the mRNAs encoding the testicular and the pulmonary isozymes but also a stretch of sequence near the 5' end unique to the testicular mRNA.     

Cytoplasmic sequence required for basolateral targeting of LDL receptor in livers of transgenic mice

When expressed in livers of transgenic mice, the human low density lipoprotein (LDL) receptor is specifically targeted to the basolateral (sinusoidal) surface of hepatocytes as determined by immunofluorescence and immunoelectron microscopy. The COOH-terminal cytoplasmic domain of the receptor (residues 790-839) contains a signal for this targeting. A mutant receptor truncated at residue 812 was localized exclusively to the apical (bile canalicular) surface. A mutant receptor terminating at residue 829 showed the normal basolateral distribution, as did a receptor in which alanine was substituted for serine 833, which was previously shown to be a site for phosphorylation in vitro. These data localize the basolateral targeting signal to the 17-residue segment between residues 812 and 828. A 10-amino acid stretch within this segment shows a 4/10 match with a sequence within a previously identified basolateral sorting motif for the receptor for polymeric IgA/IgM in MDCK cells. The four shared residues are spaced at intervals of three, raising the possibility that they all face the same side of an alpha-helix. We conclude that this 10-amino acid stretch may contain a signal that directs certain proteins, including the LDL receptor and the polymeric IgG/IgM receptor, to the basolateral surface of polarized epithelia.