Comparative digestive biology between the ponyfishes from the Pranburi River estuary, Thailand.

We investigated the digestive biology of two prevalent leiognathid species in Pranburi River estuary, Thailand: the decorated ponyfish (Nuchequula gerreoides) and the splendid polyfish (Eubleekeria splendens). A total of 632 samples collected from February to April and September to November 2017 were analysed using morphological and histological approaches. The overall structures were similar between the species: a short mucous-cell-rich oesophagus region, a well-developed gastric gland uniformly present across the stomach's mucosal layer, and three finger-like pyloric caeca between the stomach and intestine. However, there were marked differences in the mouth, gill raker, and intestinal coefficient (IC). N. gerreoides had a relatively longer mouth, smoother gill rakers, and an IC of 1.08 ± 0.01, similar to those of other carnivorous fish. In contrast, the gill raker of E. splendens had more villiform teeth that can filter-feed better, and their IC was 2.16 ± 0.02 (i.e., longer intestine). Although digestive structures were generally similar between the ponyfishes, these differences suggest that N. gerreoides is relatively carnivorous with stronger suction, whereas E. splendens may be an omnivorous or herbivorous filter-feeder.

Axonopathy and Reduction of Membrane Resistance: Key Features in a New Murine Model of Human GM1-Gangliosidosis.

GM1-gangliosidosis is caused by a reduced activity of ß-galactosidase (Glb1), resulting in intralysosomal accumulations of GM1. The aim of this study was to reveal the pathogenic mechanisms of GM1-gangliosidosis in a new Glb1 knockout mouse model. Glb1-/- mice were analyzed clinically, histologically, immunohistochemically, electrophysiologically and biochemically. Morphological lesions in the central nervous system were already observed in two-month-old mice, whereas functional deficits, including ataxia and tremor, did not start before 3.5-months of age. This was most likely due to a reduced membrane resistance as a compensatory mechanism. Swollen neurons exhibited intralysosomal storage of lipids extending into axons and amyloid precursor protein positive spheroids. Additionally, axons showed a higher kinesin and lower dynein immunoreactivity compared to wildtype controls. Glb1-/- mice also demonstrated loss of phosphorylated neurofilament positive axons and a mild increase in non-phosphorylated neurofilament positive axons. Moreover, marked astrogliosis and microgliosis were found, but no demyelination. In addition to the main storage material GM1, GA1, sphingomyelin, phosphatidylcholine and phosphatidylserine were elevated in the brain. In summary, the current Glb1-/- mice exhibit a so far undescribed axonopathy and a reduced membrane resistance to compensate the functional effects of structural changes. They can be used for detailed examinations of axon-glial interactions and therapy trials of lysosomal storage diseases.