Present and Future Salmonid Cytogenetics

Salmonids are extremely important economically and scientifically; therefore, dynamic developments in their research have occurred and will continue occurring in the future. At the same time, their complex phylogeny and taxonomy are challenging for traditional approaches in research. Here, we first provide discoveries regarding the hitherto completely unknown cytogenetic characteristics of the Anatolian endemic flathead trout, Salmo platycephalus, and summarize the presently known, albeit highly complicated, situation in the genus Salmo. Secondly, by outlining future directions of salmonid cytogenomics, we have produced a prototypical virtual karyotype of Salmo trutta, the closest relative of S. platycephalus. This production is now possible thanks to the high-quality genome assembled to the chromosome level in S. trutta via soft-masking, including a direct labelling of repetitive sequences along the chromosome sequence. Repetitive sequences were crucial for traditional fish cytogenetics and hence should also be utilized in fish cytogenomics. As such virtual karyotypes become increasingly available in the very near future, it is necessary to integrate both present and future approaches to maximize their respective benefits. Finally, we show how the presumably repetitive sequences in salmonids can change the understanding of the overall relationship between genome size and G+C content, creating another outstanding question in salmonid cytogenomics waiting to be resolved.

DNA-uptake pilus ofVibrio choleraecapable of kin-discriminated auto-aggregation

Natural competence for transformation is a widely used and key mode of horizontal gene transfer that can foster rapid bacterial evolution. Competent bacteria take-up DNA from their environment using Type IV pili, a widespread and multi-purpose class of cell surface polymers. However, how pili facilitate DNA-uptake has remained unclear. Here, using direct labelling, we show that in the Gram-negative pathogenVibrio choleraeDNA-uptake pili are highly dynamic and that they retract prior to DNA-uptake. Unexpectedly, these pili can self-interact to mediate auto-aggregation of cells into macroscopic structures. This phenotype is conserved in disease causing pandemic strains. However, extensive strain-to-strain variability in the major pilin subunit PilA, present in environmental isolates, controls the ability of pili to interact without affecting transformation. We go on to show that interactions between pili are highly specific, enabling cells producing pili composed of different PilA subunits to discriminate between one another. On chitin surfaces, a natural habitat ofV. cholerae, pili connect cells within dense networks, suggesting a model whereby DNA-uptake pili function to promote inter-bacterial interactions during surface colonisation. Moreover, our results provide evidence that type IV pili could provide a simple and potentially widespread mechanism for bacterial kin recognition.

Novel 99mTc labelled complexes with 2-nitroimidazole isocyanide: design, synthesis and evaluation as potential tumor hypoxia imaging agents

99mTc-2c can be prepared by a direct labelling method without the need for heating and would be a promising probe for hypoxia imaging.

Biological Evaluation of 99mTc-Kanamycin for Infection Imaging

Kanamycin antibiotic was radiolabeled successfully with radioisotope technetium-99m for the potential use as radiopharmaceuticals for infection imaging. ^99mTc-kanamycin complexes was prepared 93 % radiochemical purities by direct labelling using 5 mg kanamycin and 30 µg SnCl2. The reaction occurred at alkaline condition (pH=9) and under room temperature for 30 min to achieve high radiochemical purity. Radiochemical purity and stability of ^99mTc-kanamycin was determined by ascending paper chromatography using Whatman 3 paper as the stationary phase, and acetone as the mobile phase to separate the radiochemical impurities in the form of ^99mTc-pertechnetate. While impurities in the form of ^99mTc-reduced were separated using the stationary phase ITLC-SG and 0.5 N NaOH as mobile phase. This study aimed to determine biological characteristic of ^99mTc-kanamycin radiopharmaceutical. In vitro cell studies showed that the change of kanamycin structure after labeling with technetium-99m did not give a specific influence to the potency of kanamycin as an antibiotic. In addition on uptake study, a significantly higher uptake of ^99mTc-kanamycin with S. aureus than E. coli. Biodistribution of ^99mTc-kanamycin complexes was studied on normal and infection mice at 15, 30, 60 and 120 min post-injections. The biodistribution of ^99mTc-kanamycin in infection mice showed that the complex accumulated in the infection sites. These results show that ^99mTc-Kanamycin radiopharmaceutical have a potential application for infection diagnosis.