Core bacteria associated with Cochlodinium polykrikoides(Dinophyta) blooms: diversity and function

Abstract

Harmful algal blooms (HABs) of Cochlodinium polykrikoides exert pressure on nutritional resources; however, little is known about how they affect bacterial diversity. To investigate this, 110 water samples were collected from the Southern Sea of South Korea. Samples were divided into three groups based on environmental factors and phytoplankton data with a similarity of 85% using non-metric multidimensional scaling. Group I represented high-severity blooms and had a mean C. polykrikoides abundance of 1,560 cells mL. Groups II and III represented low-severity blooms, with mean densities of 68 and 57 cells mL, respectively. Inorganic nitrogen and phosphorous and dissolved organic carbon concentrations increased with C. polykrikoides density. This may reflect the change in biogeochemical cycling due to HAB release of extra polymeric substances. Furthermore, a total of 88 core bacterial operational taxonomic units (OTUs, with relative abundance > 1%) were identified. These included Gammaproteobacteria (36 OTUs), Flavobacteriia (24), Alphaproteobacteria (18), and other taxa (11). In Group I, the relative abundances of Gammaproteobacteria and Alphaproteobacteria were higher, and the relative abundance of Flavobacteriia was lower compared those in Groups II and III. Functional analysis based on the core bacterial OTUs revealed that chemoheterotrophy-related functions were more common in Group I than in Groups II and III. OTU #030, which was selected as strong indicator species, was strongly positive correlated with C. polykrikoides abundance (r = 0.95). Our results demonstrate that there are complex interactions between HABs, environmental factors, and core bacteria and functions, which could have important implications for biogeochemical cycling.

The Impact of Myosteatosis on Cardiac Function in a Healthy Population: Insights from Abdominal CT Imaging

“…As a myosteatosis index, we used the NAMA/TAMA index, which was calculated by dividing NAMA by TAMA and multiplying the result by 100. 3 A higher NAMA/TAMA index value represents a higher degree of good-quality muscle. 15…”

“…1 Our previous study demonstrated that myosteatosis was independently associated with systemic and hepatic insulin resistance, regardless of body size and the presence of other metabolic risk factors. 3 Computed tomography (CT) is commonly used to evaluate myosteatosis as a non-invasive alternative to muscle biopsy, providing reliable results that correlate with biopsy findings. 4,5 Given that CT density decreases with fatty tissue infiltration, the total abdominal muscular area (TAMA) in the CT axial image can be separated into three components based on CT density: normal-attenuation muscle area (NAMA), low-attenuation muscle area (LAMA), and inter-or intramuscular adipose tissue (IMAT).…”

“…5 Individuals with a higher NAMA/TAMA index were shown to have a lower risk of subclinical coronary atherosclerosis 7 and more favorable metabolic characteristics, including less degree of systemic insulin resistance. 3 Insulin-resistant conditions can induce cardiac dysfunction similar to that of diabetic cardiomyopathy, even in individuals without clinical diabetes mellitus. 8 A significant association between the left ventricular (LV) diastolic function and the homeostasis model assessment of insulin resistance (HOMA-IR) has been consistently demonstrated in individuals with or without diabetes.…”