Length ratio, histological structure, feed composition, and enzyme activity in the gut of yellow rasbora (Rasbora lateristriata Blkr.)

A study of the ratio of gut length, histological structure, feed composition, and enzyme activity in the foregut had carried out to determine the feed category of yellow rasbora. The study used a survey method with sampling in the Banjaran River, Banyumas, Central Java. The research data had analyzed quantitatively and descriptively. The results showed that the gut length ratio of yellow rasbora ranged from 0.53 to 0.81. Gut histological showed no stomach structure with the relative height of the villi in the middle intestine approaching 0.5. Feed composition in the foregut showed that 60% was animal, and the rest were detritus and microalgae. Measurement of protease activity at foregut showed that no acidic protease activity but found alkaline proteases. In conclusion, yellow rasbora was an omnivorous fish with a short intestine and no functioning stomach.

Morphology, Food and Feeding Habit of Goby Fish, Parachaeturichthys ocellatus from the Creeks of Mumbai

Goby fish Parachaeturichthys ocellatus, native to the creeks of Mumbai coast forms a major part of creek fishery for the fishing community inhabiting areas near the creeks. The food and feeding habits of the fish were studied by collecting fish samples every month in from June 2010 to September 2011 from the creeks of Mumbai. The length of the fishes studied ranged between 66mm to 185mm.The body morphology of fish revealed it to be carnivorous benthic and predatory fish. The gut contents of the fish showed the presence of crustaceans as basic food, mollusc and pisces formed the secondary food while detritus formed obligatory food and planktons and other miscellaneous food (larvae of insects, worms, rotiferons, dinoflegellates foraminiferons etc.) were incidental food. An analysis of seasonal variation in food preference and feeding intensity reveal that the male and female P.ocellatus had the same preference throughout the seasons but was different for the juveniles. In P.ocellatus cannibalism was observed, but its occurrence was not regular in the general diet. The relative gut length was 0.68 in male, 0.70 in female and 0.79 in juvenile. The empty guts of P.ocellatus seem to indicate predatory mode of feeding. P.ocellatus occupy the position of secondary and tertiary consumers in the food chain determined by the size and type of the food consumed by the fish.

DNA methylation site loss for plasticity-led novel trait genetic fixation

Many organisms exhibit phenotypic plasticity that changes their traits in response to their environment. Although whether or not this plasticity contributes to adaptive evolution is a fundamental question in evolutionary biology, various studies report that natural populations adapt to rapid environmental changes via plasticity, which leads to novel adaptive traits as “triggers.” Namely, phenotypic plasticity has considered allowing an accumulation of genetic mutations to fix the alternative phenotypes induced by nongenetic perturbations that include gene expression noise or epigenetic modification caused by environmental change. However, because the molecular mechanism of phenotypic plasticity is unknown, verification of the process from phenotypic plasticity to genetic fixation remains insufficient. Here we show that decrease in methylated CpG sites leads to loss of plasticity, which triggers genetic fixation of novel traits, in medaka fish (Oryzias latipes). We found that the gut length was correlated with the number of methylated CpG sites upstream of the Plxnb3 gene, which is involved in the developmental process of nerve axons. The medaka, in which the methylated DNA region is deleted by CRISPR/Cas9, showed a loss of plasticity in gut length and a lower survival rate caused by nonoptimal feeding environments. Moreover, standing variation in the promoter region of another gene, Ppp3r1, which is also related to nerve axon development, raised the gene expression and made a longer gut stably in wild medaka groups that lost the gut-length plasticity. Furthermore, our phylogenetic analysis revealed the timing of these evolutionary events, indicating that the loss of phenotypic plasticity by nucleotide substitutions initiates the process of genetic fixation of the novel trait. That is, while phenotypic plasticity plays a role as a buffer of evolution and contributes to environmental adaptation, as previously thought, our molecular data suggest that mutation on CpG site causing the loss of phenotypic plasticity, is the trigger for a generation of novel traits.

Glucagon receptor antagonist upregulates circulating GLP-1 level by promoting intestinal L-cell proliferation and GLP-1 production in type 2 diabetes

ObjectiveGlucagon receptor (GCGR) blockage improves glycemic control and increases circulating glucagon-like peptide-1 (GLP-1) level in diabetic animals and humans. The elevated GLP-1 has been reported to be involved in the hypoglycemic effect of GCGR blockage. However, the source of this elevation remains to be clarified.Research design and methodsREMD 2.59, a human GCGR monoclonal antibody (mAb), was administrated for 12 weeks in db/db mice and high-fat diet+streptozotocin (HFD/STZ)-induced type 2 diabetic (T2D) mice. Blood glucose, glucose tolerance and plasma GLP-1 were evaluated during the treatment. The gut length, epithelial area, and L-cell number and proliferation were detected after the mice were sacrificed. Cell proliferation and GLP-1 production were measured in mouse L-cell line GLUTag cells, and primary mouse and human enterocytes. Moreover, GLP-1 receptor (GLP-1R) antagonist or protein kinase A (PKA) inhibitor was used in GLUTag cells to determine the involved signaling pathways.ResultsTreatment with the GCGR mAb lowered blood glucose level, improved glucose tolerance and elevated plasma GLP-1 level in both db/db and HFD/STZ-induced T2D mice. Besides, the treatment promoted L-cell proliferation and LK-cell expansion, and increased the gut length, epithelial area and L-cell number in these two T2D mice. Similarly, our in vitro study showed that the GCGR mAb promoted L-cell proliferation and increased GLP-1 production in GLUTag cells, and primary mouse and human enterocytes. Furthermore, either GLP-1R antagonist or PKA inhibitor diminished the effects of GCGR mAb on L-cell proliferation and GLP-1 production.ConclusionsThe elevated circulating GLP-1 level by GCGR mAb is mainly due to intestinal L-cell proliferation and GLP-1 production, which may be mediated via GLP-1R/PKA signaling pathways. Therefore, GCGR mAb represents a promising strategy to improve glycemic control and restore the impaired GLP-1 production in T2D.

Food and feeding behaviours of Spotfin Swamp Barb Puntius sophore (Hamilton, 1822) of Singhiya River, Biratnagar

The present work attempt to present a novel approach about the food and feeding habits of Puntius sophore collected from Singhiya River, Biratnagar. For the study 120 specimens were collected on the monthly basis from March to August 2019, direct from the river with the help of local fisherman. On the basis of percentage of occurrence of gut content analysis the most preferred food item was Green algae (40.6%) followed by diatoms (16.10%), crustaceans (13.50%), protozoan (9.20%), detritus and debris (8.40%), insect larva (7.70%) and rotifers (4.50%). Relative gut length was the lowest at size 4.4-5.1 cm SL and the highest value at size 9.3-10 cm SL. Gastro somatic index was highest peak at the size of 4.4-5.1 cm SL, which indicate the voracious nature of fish at smaller size. The standard length and body weight show a positively significant with alimentary canal length (r=0.878) and alimentary canal weight (r=0.86.4), respectively. The food and feeding behavior of this fish showed that it is omnivores in nature.

Food Preference of Shortfin Scad (Decapterus macrosoma) at the Southern Waters of Gunungkidul Yogyakarta, Indonesia [Preferensi pakan ikan layang deles (Decapterus macrosoma) di Pantai Selatan Gunungkidul Yogyakarta]

The food habit is one of the important information used in the fisheries resource management. This study aimed to determine food preferences, index of preponderance, and trophic level of shortfin scad (D. macrosoma) captured from the southern waters of Gunungkidul Yogyakarta, Indonesia. A total of 325 fish samples were collected from March to September 2018. Each fish sample was measured in total length, body weight, determined its sex, and then dissected. The digestive tract was measured in total length then the gut contents were preserved in 5% formaldehyde to observe the type of food composition. The results showed that shortfin scad was carnivorous fish (relative gut length = 0.47) with the diet composing of fish (84.15%), phytoplankton (8.91%), zooplankton (4.47%), and snipping shrimp (3.19%). The molecular identification showed that the main fish species eaten by shortfin scad was Cololabis saira (Scomberesocoidae).AbstrakKebiasaan pakan ikan merupakan salah satu informasi penting yang digunakan dalam manajemen sumberdaya perikanan. Penelitian ini bertujuan untuk mengetahui preferensi pakan, indeks bagian terbesar dan tingkat trofik ikan layang deles (D. macrosoma) yang ditangkap dari Perairan Gunungkidul. Total 325 sampel ikan layang deles dikumpulkan selama bulan Maret sampai dengan September 2018. Setiap sampel ikan diukur panjang total, berat tubuh, ditentukan jenis kelaminnya kemudian dilakukan pembedahan. Saluran pencernaan diukur panjangnya, kemudian isi lambung ikan diawetkan dalam formalin 5% untuk diamati komposisi jenis makanannya. Analisis data meliputi panjang usus relatif, frekuensi kejadian, indeks bagian terbesar, dan tingkat trofik ikan layang deles. Hasil penelitian menunjukkan bahwa ikan layang deles bersifat karnivora (panjang usus relatif = 0,47) dengan komposisi jenis makanan utama adalah ikan (84,15%). Makanan pelengkap layang deles adalah fitoplankton (8,91%), sedangkan zooplankton (4,47%) dan potongan udang (3,19%) merupakan makanan tambahan. Berdasarkan identifikasi molekuler, spesies ikan yang menjadi makanan utama ikan layang deles adalah Cololabis saira (Scomberesocoidae).

KEBIASAAN MAKAN IKAN JANJAN Pseudapocryptes elongatus DI KALI MIRENG KABUPATEN GRESIK PADA NOPEMBER-JANUARI

Pseudapocryptes elongatus adalah sejenis Mudskipper yang ditemukan di muara-muara atau mulut sungai. Pseudapocryptes elongatus dikenal dengan ikan janjan. Para penduduk setempat menangkap ikan ini untuk digunakan sebagai ikan konsumsi karena mempunyai rasa yang gurih dan tekstur yang lembut, sampai saat ini permintaan terhadap ikan janjan masih tinggi, namun keberadaan ikan janjan masih tergantung dari hasil tangkapan nelayan. Keberadaanya beberapa tahun terakhir mulai menurun ditandai dengan semakin kecilnya ukuran ikan hasil tangkapan dan semakin menurun hasil tangkapan maka keberadaannya di alam terancam mengalami kepunahan. Domestikasi merupakan salah satu cara untuk mencegah ikan janjan dari kepunahan, tetapi informasi tentang biologi ikan janjan masih sangat terbatas, termasuk tentang kebiasaan makan. Penelitian ini bertujuan untuk mengetahui kebiasaan makan ikan janjan pada bulan Nopember sampai Januari, sehingga akan bermanfaat sebagai acuan usaha domestikasi. Metode penelitian bersifat deskriptif dengan cara mengambil ikan janjan di muara kali miring kabupaten Gresik dua minggu sekali dari bulan Nopember sampai Agustus. Ikan kemudian diukur panjang dan ditimbang beratnya, kemudian dibedah untuk diambil saluran pencernaannya untuk dilakukan analisis tentang kebiasaan makan. Hasil dari penelitian ini menunjukkan bahwa ikan janjan merupakan ikan omnivora dengan Relative Gut Length < 3, dengan makanan utama berupa diatom (37,57%), disusul kemudian oleh Rotifera, Cyanophyta, Protista, Chlorophyta, dan Arthropoda sebesar (30,69%; 26, 39%; 4%; 1,22% dan 0,12% berturut-turut).

The Relative Gut Length and Gastro-somaticindexes of the Mudskipper Periophthalmodon septemradiatus (Hamilton, 1822) from the HauRiver

This study provided an understanding of feeding habit and intensity of the mudskipper Periophthalmodon septemradiatus, which was a potential aquarium pet, by analyzing the relative gut length (RGL) andgastro-somatic (GaSI) indexes. Fish specimens were caught by fishing rods from the estuary in Soc Trang province to the upstream in An Giang province of Hau River during a period of one year from August 2017 to July 2018. Data analysis of a collection of 1,504 fishes showed that RGL did not change with fish size, resulting in the feeding habit of P. septemradiatus did not change with fish size. By contrast, the feeding habit of this mudskipper varied with place, month and season as the RGL significantly different between place, month and season, but both males and females fall into carnivorous fish as RGL was <1. Similarly, the feeding intensity of this specice did not change with fish size, as the GaSI was not significantly different among four fish size groups. Meanwhile, the mudskipper displayed spatial, temporal and seasonal variations in feeding intensity since GaSI significantly changed with place, month and season. The changes of feeding habit and intensity of P. Septemradiatus were not regulated by the interaction of fish size and place, fish size and season, and place and season. These results provided new knowledge on feeding habit and intensity of this fish specice, being used for the understanding of fish adaption and conservation in the study region. Keywords Gastro-somatic index, mudskipper, Periophthalmodon septemradiatus, relative gut length References [1] Murdy, E. O. & Jaafar, Z., Taxonomy and systematics review, In: Z. Jaafar, E. O. Murdy (eds) Fishes out of water: biology and ecology of mudskippers, CRC Press, Boca Raton, pp. 1-36, 2017 [2] Murdy, E. O., A taxonomic revision and cladistic analysis of the oxudercine gobies (Gobiidae, Oxudercinae), Australian Museum Journal, 11 (1989) 93.[3] Murdy, E., Systematics of Oxudercinae, In: R. A. Patzner, J. L. V. Tassell, M. Kovacic, B. G. Kapoor (eds) The biology of gobies, Science Publishers, New Hampshire, United States, pp. 99-106, 2011 [4] Bhatt, N. Y., Patel, S. J., Patel, D. A. & Patel, H. P., Burrowing activities of goby fish in the recent intertidal mud flats along the Navinal coast, Kachchh, Western India, Journal of the Geological Society of India, 74 (2009) 515-530.[5] Al-Hussaini, A. H., On the functional morphology of the alimentary tract of some fish in relation to differences in their feeding habits: anatomy and histology, Quarterly Journal of Microscopical Science, 3 (1949) 109-139.[6] Desai, V. R., Studies on fishery and biology of Tor tor (Hamilton) from river Narmada. I. Food and feeding habits, Journal of the Inland Fisheries Society of India, 2 (1970) 101-112.[7] Le, T., Nguyen, M. T., Nguyen, V. P., Nguyen, D. C., Pham, X. H., Nguyen, T. S., Hoang, V. C., Hoang, P. L., Le, H. & Dao, N. C., Provinces and City in the Mekong Delta, Education Publishing House, Ha Noi, 2006.[8] Khaironizam, M. Z. & Norma-Rashid, Y., First record of the mudskipper, Periophthalmodon septemradiatus (Hamilton) (Teleostei: Gobiidae) from Peninsular Malaysia, Raffles Bulletin of Zoology, 51 (2003) 97-100.[9] Wand, M. P., Data-based choice of histogram bin width, The American Statistician, 51 (1997) 59-64.[10] Vo, T. T. & Tran, D. D., Study on nutritional characteristics of Oxyeleotris urophthalmus fish distributed along the Hau River, Can Tho University Journal of Science, Fishery (2014) 192-197.[11] Dinh, Q. M., Nguyen, D. T. & Danh, S., Food and feeding habits of the broadheah sleeper Eleotris melanosoma from coastline in Soc Trang, Proceedings of the 7th National Scientific Conference on Ecology and Biological Resources, Publishing house for Science and Technology, 1873-1879, 2017.[12] Tran, D. D., Some aspects of biology and population dynamics of the goby Pseudapocryptes elongatus (Cuvier, 1816) in the Mekong Delta, PhD thesis, Universiti Malaysia Terengganu, 2008.[13] Dinh, Q. M., Qin, J. G., Dittmann, S. & Tran, D. D., Seasonal variation of food and feeding in burrowing goby Parapocryptes serperaster (Gobiidae) at different body sizes, Ichthyological Research, 64 (2017) 179-189.[14] Dinh, Q. M. & Tran, M. T. D., Digestive tract morphology, food and feeding habits of the goby Stigmatogobius pleurostigma (Bleeker, 1849) from the Coastline in Soc Trang, VNU Journal of Science: Natural Sciences and Technology, 34 (2018) 46-55.

Bioavailability and Safety of Nutrients from the Microalgae Chlorella vulgaris, Nannochloropsis oceanica and Phaeodactylum tricornutum in C57BL/6 Mice

Microalgae are rich in macronutrients and therefore, they have been proposed as a potential future food source preserving natural resources. Here, we studied safety and bioavailability of algae nutrients in mice. Three microalgae species, Chlorella vulgaris, Nannochloropsis oceanica and Phaeodactylum tricornutum, were studied after ball mill disruption at different doses (5%, 15% and 25% dry weight) for 14 days. In response to all three algae diets, we observed a weight gain similar or superior to that in response to the control diet. No substantial differences in organ weights nor gut length occurred. Protein bioavailability from the algae diets did not differ from the control diet ranging from 58% to 77% apparent biological value. Fat absorption was lower for microalgae compared to soy oil in control diets, albeit still substantial. High liver eicosapentaenoic acid levels were measured following feeding with N. oceanica, the algae richest in omega-3 fatty acids. Neither histological nor serum analyses revealed any heart, kidney or liver toxicity induced by any of the algae diets. Algae-rich diets were thus well accepted, well tolerated and suitable for the maintenance of body weight and normal organ function. No toxicological effects were observed.