Disclosure of genetic diversity of mackerel fish (Scomberomorus spp.) in Indonesian waters based on the mitochondrial cytochrome oxidase subunit II (COII) gene.

Mackerel fish (Scomberomorus spp.) represents a significant marine fisheries commodity in Indonesia, characterized by its high commercial value and nutritional content. To understand the intraspecific interactions and genetic variability of Scomberomorus spp., a more extensive research of Scomberomorus spp. populations, including both cultivated and wild specimens, is required. This study aimed to explore the genetic diversity of mackerel fish in Indonesian waters, focusing on the mitochondrial DNA (mtDNA) cytochrome oxidase subunit II (COII) gene, which encodes the second subunit of cytochrome c oxidase (complex IV), is essential for aerobic respiration and energy transformation. Muscle tissue samples from 18 individual mackerel fish collected from various regions in Indonesia, including Palembang, Cilacap, Rembang, Banjarmasin, Ambon, and Fak-Fak Regencies, were utilized. The genomic DNA was isolated and amplified using specific primers: CO2TF (5'-ACCGCTCTGTCACTTTCTTC-3') and CO2TR (5'-ATGTCACTAAGGGTGGTTGG-3'). Subsequently, the obtained amplicons were subjected to sequencing. The sequence data were then analyzed using the MEGA11 and DnaSP 6 software. Our findings revealed 120 variable sites within the 691 base pairs of mtDNA COII sequences, resulting in a nucleotide diversity (Pi) of 0.07169. Furthermore, we identified eight haplotypes, demonstrating a haplotype diversity (Hd) of 0.8889. Remarkably, all mackerel samples from Palembang and Cilacap clustered into discrete haplotypes, specifically haplotype 1 and haplotype 2, respectively. Our phylogenetic analysis delineated three distinct clades. Clade I, closely related to Scomberomorus cavalla, encompassed all individuals from Ambon, Palembang, Rembang, and one from Banjarmasin. Clade II, associated with Scomberomorus niphonius, included individuals from Cilacap and two from Banjarmasin. Clade III, linked to Scomberomorus semifasciatus, exclusively consisted of individuals from Fak-Fak (Papua). In conclusion, Indonesian waters harbor diverse genetic variations within Scomberomorus spp., and population relationships based on the mtDNA COII gene exhibit notable complexities. Future research endeavors should focus on further elucidating the diversity and relationships among Scomberomorus spp. in diverse Indonesian populations.

The role of bacterial stimuli in inflammation-driven bone formation.

Immune cells and their soluble factors regulate skeletal cells during normal bone regeneration and pathological bone formation. Bacterial infections can trigger immune responses that activate pro-osteogenic pathways, but these are usually overshadowed by osteolysis and concerns of systemic inflammation. The aim of this study was to determine whether the transient local inflammatory reaction to non-viable bacterial immune agonists could lead to favourable new bone formation. In a series of rabbit studies, as proof-of-concept, how tibial intramedullary injection of viable or killed bacterial species affected bone remodelling and new bone formation was determined. Application of killed bacteria led to considerable new bone formation after 4 weeks, without the prolonged systemic inflammation and exaggerated bone lysis seen with active infection. The osteo-immunomodulatory effects of various species of killed bacteria and the dose response relationship were subsequently screened in ectopically-implanted ceramic scaffolds. Histomorphometry after 8 weeks showed that a relatively low dose of killed bacteria enhanced ectopic bone induction. Moreover, lipoteichoic acid - the bacterial cell-wall derived toll-like-receptor (TLR)-2 activator - was identified as an osteo-stimulatory factor. Collectively, the data indicated that bacterial stimuli could be harnessed to stimulate osteogenesis, which occurs through a synergy with osteoinductive signals. This finding holds promise for the use of non-viable bacteria, bacterial antigens, or their simplified analogues as immuno-modulatory bone regenerating tools in bone biomaterials.