| 1. |
- Beal, Jacob, et al.
(author)
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Robust estimation of bacterial cell count from optical density
- 2020
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In: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Journal article (peer-reviewed)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 2. |
- Guo, Haoyu, et al.
(author)
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Evaluation of starvation status in the early developmental stages of black rockfish (Sebastes schlegelii) based on morphological and histological characteristics
- 2023
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In: Journal of Fish Biology. - 0022-1112 .- 1095-8649.
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Journal article (peer-reviewed)abstract
- Assessing the nutritional status and identifying major causes of mortality in larvae experiencing varying degrees of starvation are crucial for establishing appropriate feeding protocols and enhancing the welfare of hatchery-reared fish. The black rockfish Sebastes schlegelii is an important species in aquaculture and stock enhancement efforts in China, Japan, and Korea. This study aimed to identify optimal diagnostic morphometric indicators of starvation in newly hatched (0–6 days post-hatch, DPH) and postlarval stages (27–37 DPH) of this valuable fish species through histological analyses. Our findings revealed that certain morphometric parameters, including body length, the ratios of eye diameter to head height, body height to body length, and abdomen height to body height, exhibit sensitivity to starvation during both larval and postlarval stages. Particularly, the ratios of body height to body length and abdomen height to body height emerged as the most sensitive morphometric indicators of starvation. Histological examinations of the digestive system revealed rapid alterations in the morphology of hepatic parenchymal cells, accompanied by a significant decrease in the number of lipid cells in the liver during episodes of food deprivation. Starvation induced cellular degeneration in the digestive organs, manifested by reduced heights of epithelial cells and mucosal layers in the intestine, oesophagus, and stomach, along with degeneration and separation of muscle fibers. Among these variables, the height of the intestinal submucosa and muscle layer emerged as the most sensitive indicators reflecting nutritional conditions in newly hatched larvae. In contrast, the height of intestinal striated borders and mucosal folds proved to be the most sensitive indicators in the postlarval stage. Furthermore, the height of intestinal epithelial cells and the number of lipid vacuoles in enterocytes exhibited high sensitivity to food deprivation in both newly hatched larvae and postlarvae. These findings underscore the varying resilience of fish to starvation during different developmental phases and highlight the utility of morphological sensitivity characteristics as reliable diagnostic indices for assessing nutritional status in relation to starvation or suboptimal feeding during the early developmental stages of black rockfish in hatchery-reared processes.
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