Downsized: gray whales using an alternative foraging ground have smaller morphology.

Describing individual morphology and growth is key for identifying ecological niches and monitoring the health and fitness of populations. Eastern North Pacific ((ENP), approximately 16 650 individuals) gray whales primarily feed in the Arctic/sub-Arctic regions, while a small subgroup called the Pacific Coast Feeding Group (PCFG, approximately 212 individuals) instead feeds between northern California, USA and British Columbia, Canada. Evidence suggests PCFG whales have lower body condition than ENP whales. Here we investigate morphological differences (length, skull, and fluke span) and compare length-at-age growth curves between ENP and PCFG whales. We use ENP gray whale length-at-age data comprised of strandings, whaling, and aerial photogrammetry (1926-1997) for comparison to data from PCFG whales collected through non-invasive techniques (2016-2022) to estimate age (photo identification) and length (drone-based photogrammetry). We use Bayesian methods to incorporate uncertainty associated with morphological measurements (manual and photogrammetric) and age estimates. We find that while PCFG and ENP whales have similar growth rates, PCFG whales reach smaller asymptotic lengths. Additionally, PCFG whales have relatively smaller skulls and flukes than ENP whales. These findings represent a striking example of morphological adaptation that may facilitate PCFG whales accessing a foraging niche distinct from the Arctic foraging grounds of the broader ENP population.

Does chronic hypoxaemia induce transformations of fibre types?

The study comprised nine patients with chronic obstructive lung disease. Quadriceps muscle biopsies were studied with respect to fibre type composition before and after haemodilution that brought haemoglobin (Hb) to within normal limits. Ten days elapsed between the two biopsy occasions. The arterial oxygen tension (PaO2) and saturation (SaO2) were depressed to 8.4 +/- 2.0 kPa and 89 +/- 11% in the patients with chronic obstructive lung disease and increased to 9.2 +/- 2.1 and 91 +/- 8% with haemodilation. The type II fibre proportion was 71 +/- 12% before haemodilation and significantly higher than normal (reference group, see Aniansson et al. 1981). Following haemodilation the proportion of type II fibres decreased significantly to 60 +/- 14%. The proportion of type II fibres was directly related to the haemoglobin content before, but not after, haemodilation and was inversely related to PaO2 and SaO2 both before and after haemodilation. In conclusion, hypoxaemia may be a factor underlying the high proportion of type II fibres found in patients with chronic obstructive lung disease.

Skeletal muscle depressed calcium and phosphofructokinase in chronic heart failure are upregulated by captopril--a double-blind, placebo-controlled study.

The effects of the angiotensin converting enzyme inhibitor captopril, after treatment for 5-6 weeks with 25 mg t.i.d., were studied in 12 patients with stable moderate heart failure. Five patients received placebo treatment, and the two groups were comparable at baseline. Angiotensin II levels decreased in response to captopril therapy. Skeletal muscle potassium, magnesium and chloride levels did not differ from reference values. Calcium was subnormal (P less than 0.0001), but increased to the reference range during captopril treatment. Phosphofructokinase, a rate-limiting glycolytic enzyme, was in the lower reference range and increased (P less than 0.04) in response to captopril therapy. In conclusion, stable moderate heart failure is associated with low levels of skeletal muscle calcium and phosphofructokinase activity, these metabolic changes tending to return to normal levels with captopril treatment.

Decrease in myoglobin and enzyme contents with haemodilution in non-hypoxaemic polycythaemic patients.

Quadriceps muscle biopsies from five patients with primary polycythaemia and four patients with non-primary polycythaemia, all with normal respiratory functions, were studied before and after normalization of haemoglobin and erythrocyte volume fraction by haemodilution or venaesectio. Since similar results were obtained from both groups of patients data were pooled. After normalization of the erythrocyte volume fraction myoglobin decreased by 19 +/- 16%, P less than 0.01, the activity of creatine kinase and citrate synthase by 12 +/- 8 and 14 +/- 18%, P less than 0.05, respectively. The decrease in myoglobin content was related to the decrease in haemoglobin concentration (r = 0.77, P less than 0.01). In conclusion, these data suggest that in non-hypoxaemic polycythaemia skeletal muscle shows adaptations indicative of an impaired oxygenation and a metabolic stress, adaptations that are reversed by haemodilution.