A multidisciplinary effort to increase COVID-19 vaccination among the older adults.

Background: COVID-19 vaccination significantly reduces the risk of infection and its associated morbidity and mortality. However, poor uptake of the COVID-19 vaccination was reported among the high-risk group of older people amidst emerging variants of concern. This community case study reports an outreach program in Singapore, COVE (COVID-19 Vaccination for the Elderly) initiated by healthcare workers in a cluster of primary care clinics. They assessed the vaccine hesitancy among these older persons, addressed their concerns and facilitated their vaccination appointment during a brief phone conversation. Method: Twenty one thousand six hundred and sixty three unvaccinated adults aged ≥60 years were contacted by healthcare worker volunteers over two phases from June to October 2021. In phase I, they contacted adults aged above 70 years over 2 weeks. Adults who were uncontactable in phase I and those aged 60-69 years were sent SMS in phase II. Data were analyzed via descriptive data analysis. Results: After phase 1, 65.5% (n = 5,646/8,617) of older adults had received at least one dose of the COVID-19 vaccine. The respondents expressed intention to vaccinate (39%, n = 3,390), requested to seek further information (25%, n = 2,138), reported access barrier (8%, n = 715), or were concerned of the vaccine adverse effects (3%, n = 288). Vaccination was refused by 24% (n = 2,086) of the respondents. Eventually 60.4% (n = 13,082/21,663) of them were vaccinated 3 months after COVE implementation. Conclusion: The COVE program increased the COVID-19 vaccination uptake of older adults from 84.6 to 96.3%. A person-centric proactive approach by healthcare workers addressed vaccine hesitancy and optimized vaccination. The outreach scheduling of vaccination appointments is key in promoting vaccination uptake among older adults.

Establishment of a cell line with high transfection efficiency from zebrafish Danio rerio embryos and its susceptibility to fish viruses.

A cell line ZBE3 isolated from a continuous cell culture derived from zebrafish Danio rerio blastomeres by clonal growth was characterized. ZBE3 cells had been subcultured for >120 passages since the initial primary culture of the blastomeres. The ZBE3 cells grow stably at temperature from 20 to 32° C with an optimum temperature of 28° C in ESM2 or ESM4 medium with 15% foetal bovine serum (FBS). The optimum FBS concentration for ZBE3 cell growth ranged from 15 to 20%. Cytogenetical analysis indicated that the modal chromosome number of ZBE3 cells was 50, the same as the diploid chromosome number of D. rerio. Significant cytopathic effect was observed in ZBE3 cells after infection with redspotted grouper nervous necrosis virus, Singapore grouper iridovirus and grass carp reovirus, and the viral replication in the cells was confirmed by real-time quantitative PCR and transmission electron microscopy, indicating the susceptibility of ZBE3 cells to the three fish viruses. After transfected with pEGFP-N3 plasmid, ZBE3 cells showed a transfection efficiency of about 40% which was indicated by the percentage of cells expressing green fluorescence protein. The stable growth, susceptibility to fish viruses as well as high transfection efficiency make ZBE3 cells be a useful tool in transgenic manipulation, fish virus-host cell interaction and immune response in fish.

Molecular cytogenetic detection of paternal chromosome fragments in allogynogenetic gibel carp, Carassius auratus gibelio Bloch.

In gynogenesis, sperm from related species activates egg and embryonic development, but normally does not contribute genetically to the offspring. In gibel carp, Carassius auratus gibelio Bloch, however, gynogenetic offspring often show some phenotypes apparently derived from the heterologous sperm donor. This paternal effect of allogynogenesis is outstanding in an artificial clone F produced by cold treatment of clone E eggs after insemination with blunt-nose black bream (Megaloabrama amblycephala Yin) sperm. Karyotype analysis revealed 5-15 supernumerary microchromosomes in different individuals of clone F in addition to 156 normal chromosomes inherited from the maternal clone E. A painting probe was prepared from the microdissected microchromosomes, and used to investigate the origin of these microchromosomes. Strong positive signals were detected on each microchromosomes of clone F and on 4 pairs of chromosomes in blunt-nose black bream, whereas no signals were detected on the chromosomes of clone E. This result indicates that some paternal chromosome fragments of blunt-nose black bream have been incorporated into the artificial clone F. Therefore, the manipulation of allogynogenesis may provide a unique method to transfer DNA between diverse species for fish breeding.

Sex chromosomes in the spiny eel (Mastacembelus aculeatus) revealed by mitotic and meiotic analysis.

Lower vertebrates like fish exhibit tremendous diversity in sex determination. There are wide interplays between environment-dependent sex differentiation ranging from natural hermaphroditism to sex reversal and genetic sex determination. Diverse systems of male and female heterogamety coexist in fish and sex chromosomes are rarely distinguishable in morphology. Here we show that the spiny eel ((Mastacembelus aculeatus) of the Perciformes, has evolved highly heteromorphic X and Y chromosomes. The metacentric X and Y chromosomes are the largest among 24 homologous pairs, differ from each other in size and morphology, and become distinct after C-banding because of conspicuous heterochromatin blocks which exhibit alternate distribution around the centromeric region. Chromosome painting using probes from the microdissected X chromosome revealed sequence homology between X and Y. During the pachytene stage of meiosis the X and Y form a bivalent. However, their synapsis is delayed which is particularly evident in one terminus. Therefore, the X and Y have resulted from a pericentric inversion in the Y. We conclude that M. aculeatus represents an example of a highly advanced stage of sex chromosome evolution in fish.

[Painting the chromosomes of fishes with human sex chromosome-specific DNA probes].

Chromosome painting is one of the effective methods in studying the evolution of genomes. The chromosomes of the species of fishes--M. aculeatus, M. albus and D. rerio were painted respectively with human X and Y chromosome-specific DNA probes. The results showed that some homologous segments of human X chromosome were found in the genomes of all the three kind of fishes, all the segments were scattered on several pairs of homologous chromosomes in each kind of fish. But no homologous segment of the human Y chromosome was found.