Chemo-photothermal therapy of chitosan/gold nanorod clusters for antibacterial treatment against the infection of planktonic and biofilm MRSA.

Bacterial infections trigger inflammation and impede the closure of skin wounds. The misuse of antibiotics exacerbates skin infections by generating multidrug-resistant bacteria. In this study, we developed chemo-photothermal therapy (chemo-PTT) based on near-infrared (NIR)-irradiated chitosan/gold nanorod (GNR) clusters as anti-methicillin-resistant Staphylococcus aureus (MRSA) agents. The nanocomposites exhibited an average size of 223 nm with a surface charge of 36 mV. These plasmonic nanocomposites demonstrated on-demand and rapid hyperthermal action under NIR. The combined effect of positive charge and PTT by NIR-irradiated nanocomposites resulted in a remarkable inhibition rate of 96 % against planktonic MRSA, indicating a synergistic activity compared to chitosan nanoparticles or GNR alone. The nanocomposites easily penetrated the biofilm matrix. The combination of chemical and photothermal treatments by NIR-stimulated clusters significantly damaged the biofilm structure, eradicating MRSA inside the biomass. NIR-irradiated chitosan/GNR clusters increased the skin temperature of mice by 13 °C. The plasmonic nanocomposites induced negligible skin irritation in vivo. In summary, this novel nanosystem demonstrated potent antibacterial effects against planktonic and biofilm MRSA, showcasing the possible efficacy in treating skin infections.

Modulations of ocean-atmosphere interactions on squid abundance over Southwest Atlantic.

Anthropogenic shifts in seas are reshaping fishing trends, with significant implications for aquatic food sources throughout this century. Examining a 21-year abundance dataset of Argentine shortfin squids Illex argentinus paired with a regional oceanic analysis, we noted strong correlations between squid annual abundance and sea surface temperature (SST) in January and February and eddy kinetic energy (EKE) from March to May in the Southwest Atlantic. A deeper analysis revealed combined ocean-atmosphere interactions, pinpointed as the primary mode in a rotated empirical orthogonal function analysis of SST. This pattern produced colder SST and amplified EKE in the surrounding seas, factors crucial for the unique life stages of squids. Future projections from the CMIP6 archive indicated that this ocean-atmosphere pattern, referred to as the Atlantic symmetric pattern, would persist in its cold SST phase, promoting increased squid abundance. However, rising SSTs due to global warming might counteract the abundance gains. Our findings uncover a previously unrecognized link between squids and specific environmental conditions governed by broader ocean-atmosphere interactions in the Southwest Atlantic. Integrating these insights with seasonal and decadal projections can offer invaluable information to stakeholders in squid fisheries and marine conservation under a changing climate.

Factors affecting synonymous codon usage of housekeeping genes in Drosophila melanogaster.

Housekeeping genes (HK genes) are required for cell survival and the maintenance of basic cellular functions. The investigation of factors affecting codon usage patterns in HK genes of insects can help in understanding the molecular evolution of insects and aid the development of insect pest management strategies. In this study, we employed bioinformatics approaches to analyze the codon usage bias (CUB) of HK genes in the insect model organism, Drosophila melanogaster. A comparison of CUB between 1107 HK genes and 1084 high tissue specificity genes suggested that HK genes have higher CUB in D. melanogaster. In addition, we found that CUB inversely correlates with the non-synonymous substitution rate of HK genes. Therefore, we attempted to identify the factors that potentially influence the codon usage pattern of HK genes. Our results suggest that mutation pressure and natural selection highly correlate with CUB in the HK genes of D. melanogaster and that two topological properties of HK proteins (proportion of protein interacting length and protein connectivity) also correlate with CUB in the HK genes of D. melanogaster. This study provides insight into CUB in the HK genes of D. melanogaster, and the results can support future investigations of potential applications in agricultural and biomedical field.

Evaluating the accuracy of morphological identification of larval fishes by applying DNA barcoding.

Due to insufficient morphological diagnostic characters in larval fishes, it is easy to misidentify them and difficult to key to the genus or species level. The identification results from different laboratories are often inconsistent. This experiment aims to find out, by applying DNA barcoding, how inconsistent the identifications can be among larval fish taxonomists. One hundred morphotypes of larval fishes were chosen as test specimens. The fishes were collected with either larval fish nets or light traps in the northern, southern and northwestern waters of Taiwan. After their body lengths (SL) were measured and specimen photos were taken, all specimens were delivered, in turn, to five laboratories (A-E) in Taiwan to be identified independently. When all the results were collected, these specimens were then identified using COI barcoding. Out of a total of 100 specimens, 87 were identified to the family level, 79 to the genus level and 69 to the species level, based on the COI database currently available. The average accuracy rates of the five laboratories were quite low: 80.1% for the family level, 41.1% for the genus level, and 13.5% for the species level. If the results marked as "unidentified" were excluded from calculations, the rates went up to 75.4% and 43.7% for the genus and species levels, respectively. Thus, we suggest that larval fish identification should be more conservative; i.e., when in doubt, it is better to key only to the family and not to the genus or species level. As to the most misidentified families in our experiment, they were Sparidae, Scorpaenidae, Scombridae, Serranidae and Malacanthidae. On the other hand, Mene maculata and Microcanthus strigatus were all correctly identified to the species level because their larvae have distinct morphology. Nevertheless, barcoding remains one of the best methods to confirm species identification.

Genetic analysis of the populations of Japanese anchovy (Engraulidae: Engraulis japonicus) using microsatellite DNA.

We analyzed the population structure of the Japanese anchovy (Engraulis japonicus), a small pelagic fish, using 6 microsatellite DNA loci. The anchovy is known to have 2 separate spawning populations, one near northeastern Taiwan in the Pacific Ocean and the other near southwestern Taiwan in the Taiwan Strait. The planktonic larvae then drifted north to the feeding grounds in the East China Sea to advance in their life history. Three populations of the anchovy were analyzed, including 2 temporal population from the northeastern spawning ground (I-Lan 1999 and I-Lan 2000) and one population from the southwestern spawning ground (Peng-Hu 2000). The genetic variability of the 6 loci was high for all the populations. The average numbers of alleles per population ranged from 25.5 to 32.3, and the average observed heterozygosity ranged from 0.559 to 0.650. A significant population differentiation was found between geographic populations but not between the temporal populations. However, the level of geographic differentiation was weak, average FST 0.0088. The significant geographic population structure indicated that the populations of 2 spawning grounds belonged to separate stocks. Moreover, 16 of the 18 population-locus cases showed significant departure from Hardy-Weinberg equilibrium, implying that each spawning population in turn consisted of mixed native stocks. Finally, we posed 3 population models to be evaluated against the genetic data disclosed with the microsatellite markers.