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The search for bioactive compounds from enzymatic hydrolysates has increased in the last few decades. Fish by-products have been shown to be rich in these valuable molecules; for instance, herring milt is a complex matrix composed of lipids, nucleotides, minerals, and proteins. However, limited information is available on the potential health benefits of this by-product. In this context, three industrial products containing herring milt hydrolysate (HMH) were tested in both animal and cellular models to measure their effects on obesity-related metabolic disorders. Male C57Bl/6J mice were fed either a control chow diet or a high-fat high-sucrose (HFHS) diet for 8 weeks and received either the vehicle (water) or one of the three HMH products (HMH1, HMH2, and HMH3) at a dose of 208.8 mg/kg (representing 1 g/day for a human) by daily oral gavage. The impact of HMH treatments on insulin and glucose tolerance, lipid homeostasis, liver gene expression, and the gut microbiota profile was studied. In parallel, the effects of HMH on glucose uptake and inflammation were studied in L6 myocytes and J774 macrophages, respectively. In vivo, daily treatment with HMH2 and HMH3 improved early time point glycemia during the oral glucose tolerance test (OGTT) induced by the HFHS diet, without changes in weight gain and insulin secretion. Interestingly, we also observed that HMH2 consumption partially prevented a lower abundance of Lactobacillus species in the gut microbiota of HFHS diet-fed animals. In addition to this, modulations of gene expression in the liver, such as the upregulation of sucrose nonfermenting AMPK-related kinase (SNARK), were reported for the first time in mice treated with HMH products. While HMH2 and HMH3 inhibited inducible nitric oxide synthase (iNOS) induction in J774 macrophages, glucose uptake was not modified in L6 muscle cells. These results indicate that milt herring hydrolysates reduce some metabolic and inflammatory alterations in cellular and animal models, suggesting a possible novel marine ingredient to help fight against obesity-related immunometabolic disorders.

This study assessed the paternal effects on the growth of early juvenile winter flounder Pseudopleuronectes americanus and examined the energy allocation strategy employed during this critical stage. Males from three different locations (Passamaquoddy Bay, Baie-des-Chaleurs and the St Lawrence Estuary) were crossed with females from the Baie-des-Chaleurs, and the growth characteristics of hybrids from settlement to 45 days post-settlement were monitored under similar culture conditions. Young juveniles displayed good growth rates (0·09 ± 0·02 mm day −1 ), with no differences related to sire origin, in terms of growth indicators (length, width, RNA:DNA and triacylglycerol:sterol ratios), condition indices (Fulton's K, pigmentation and fin erosion) and biochemical components (nucleic acids, proteins and lipid classes). These results suggest the absence of a paternal contribution to the growth strategy during the early juvenile stage of P. americanus. The results also highlight the high energetic cost associated with metamorphosis: young juveniles mobilized most of their triacylglycerol reserves during the growth period following settlement.

Three stocks of winter flounder Pseudopleuronectes americanus are currently defined in the northwest Atlantic region: One south of Cape Cod, Massachusetts, one north of it, and a third on Georges Bank. Our objectives were to determine whether the different populations along this latitudinal gradient have similar larval development characteristics in a coldwater environment and to test the paternal contribution to larval development. We crossed breeders that had been captured on their natural spawning sites in Passamaquoddy Bay, New Brunswick, and Baie des Chaleurs and the St. Lawrence estuary, Quebec, to produce pure‐strain families (year 1) and hybrids (year 2). Larvae were reared under the salinity and temperature conditions of the St. Lawrence estuary, the northernmost site in our study. Total length and maximum width were measured from hatching to settlement. In the wild population from the St. Lawrence estuary, males were shorter and in better condition and females produced smaller eggs than those from the two more southern wild populations. The time lapse between fertilization and hatch was shorter for embryos from the Baie des Chaleurs. In both the pure and hybrid cross experiments, the different cross‐types showed similar fertilization and hatching success, size at hatch and settlement, and time until settlement but differed in larval growth rate. Larval growth was slower in families sired by St. Lawrence estuary males. When females from the Baie des Chaleurs were crossed with males from the different origins, the results were similar to those obtained in families sired by St. Lawrence estuary males. These results strongly suggest a paternal component to larval growth. Settlement, however, which appeared to be size dependent, was governed more by environmental factors than by parental ones.