Jaw malformations are a serious problem in fingerlings of the greater amberjack, Seriola dumerili. To establish a countermeasure against these malformations, we conducted a larval behavioural test to identify their root cause, and we investigated the ability of low‐brightness rearing tank walls to control their occurrence. Larval distribution was examined in a horizontally illuminated rectangular transparent aquarium (20 cm × 100 cm × 25 cm), and their distribution was biased towards the light source after this lighting was provided from 3 to 13 days post hatching (dph), indicating positive phototaxis; this response disappeared on 22 dph (there are no data between 13 and 22 dph). Larvae were observed to swim phototactically towards the light source and repeatedly collided with the tank wall (walling behaviour). To investigate the ability of wall brightness to control the incidence of jaw malformations, we compared their incidence in a rearing trial with different Munsell colour values for the tank walls: 2.11 (black), 5.85 (grey) and 9.52 (white). The incidence rate of jaw malformations at 25 dph was significantly lower in the tanks with lower‐brightness walls, that is, 5.8%, 22.5% and 26.8% for black, grey and white respectively. Larval walling behaviour was most intense for white, followed in order by grey and black. These results indicate that positive phototaxis elicits larval walling behaviour, causing jaw malformations, and that low‐brightness tank walls control this process.

We have developed an automated device for the measurement of oxygen consumption rate (OCR) called Chip-sensing Embryo Respiratory Measurement system (CERMs). To verify the safety and the significance of the OCR measurement by CERMs, we conducted comprehensive tests using a mouse model prior to clinical trials in a human in vitro fertilization (IVF) program. Embryo transfer revealed that the OCR measured by CERMs did not compromise the full-term development of mice or their future fertility, and was positively correlated with adenosine triphosphate (ATP) production and the mitochondrial membrane potential (ΔΨm), thereby indirectly reflecting mitochondrial oxidative phosphorylation (OXPHOS) activity. We demonstrated that the OCR is independent of embryo morphology (the size) and number of mitochondria (mitochondrial DNA copy number). The OCR correlated with the total cell numbers, whereas the inner cell mass (ICM) cell numbers and the fetal developmental rate were not. Thus, the OCR may serve as an indicator of the numbers of trophectoderm (TE) cells, rather than number or quality of ICM cells. However, implantation ability was neither correlated with the OCR, nor the embryo size in this model. This can probably be attributed to the limitation that chimeric embryos contain non-physiological high TE cells counts that are beneficial for implantation. CERMs can be safely employed in clinical IVF owing to it being a safe, highly effective, non-invasive, accurate, and quantitative tool for OCR measurement. Utilization of CERMs for clinical testing of human embryos would provide further insights into the nature of oxidative metabolism and embryonic viability.

We present an all-fiber tunable bandpass filter based on a combination of a force-induced long-period fiber grating and a fiber coil made along a double cladding fiber. The transmission wavelength can be tuned to be in a range of more than 100 nm by changing the grating period mechanically. We can control the transmission amplitude of the bandpass filter by adjusting the periodic force on the double cladding fiber. The ambient temperature causes a positive shift in the transmission wavelength. Such a device is useful for tunable laser applications and fiber-optic sensors.

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