Seasonal analysis of food items and feeding habits of endangered riverine catfish Rita rita (Hamilton, 1822)

This investigation presents the food and feeding activity of and endangered riverine catfish Rita rita, during February 2017-January 2018. A total of 225 fish individuals was analyzed for stomach contents by characterizing the dominant food items and morphometric features. The results divulged ten major food items consumed, preferably fish scales and eggs, teleost fishes, copepods, cladocerans, rotifers, and mollusks. Total length and body weight of fish varied between 9-34 cm (20.53 ± 6.90 cm) and 10-400 g (9125.94 ± 102.07 g), respectively. The index of relative importance (IRI%) showed the importance of rotifers over the other food items. Morisita’s index of diet overlap indicated seasonal variations in catfish diets with summer and monsoon displaying the least overlap, while maximum overlap during monsoon and winter seasons. The non-metric multidimensional scaling (nMDS) indicated the close association between the food items available during summer and winter seasons with a significant difference among the seasons (ANOSIM, R = 0.638, P = 0.013). Levin’s niche breadth index arranged in the order of 0.88>0.81>0.78>0.63>0.43 for the size classes of V, IV, III, II and I, respectively. The PCA explained 95.39% of the total variance among the food items and fish size groups. Small-sized fish individuals displayed a greater correlation with food items suitable for their mouth size. In conclusion, the variety and frequency of food items recorded indicated considerable feeding plasticity and opportunistic feeding behavior with a shift from carnivorous to omnivorous feeding nature. This study could render useful information on the food and feeding habits of R. rita and provide background for preparing its diet for future aquaculture practices.

Hedgehog signaling controls mouth opening in the amphioxus

Introduction The left-sided position of the mouth in amphioxus larvae has fascinated researchers for a long time. Despite the fundamental importance of mouth development in the amphioxus, the molecular regulation of its development is almost unknown. In our previous study, we showed that Hh mutation in the amphioxus leads to no mouth opening, indicating a requirement of Hh signaling for amphioxus mouth formation. Nevertheless, since the Hh mutant also exhibits defects in early left-right (LR) patterning, it remains currently unknown whether the loss of mouth opening is affected directly by Hh deficiency or a secondary effect of its influence on LR establishment. Results We demonstrated that knockout of the Smo gene, another key component of the Hh signaling pathway, in the amphioxus resulted in the absence of mouth opening, but caused no effects on LR asymmetry development. Upregulation of Hh signaling led to a dramatic increase in mouth size. The inability of Smo mutation to affect LR development is due to Smo’s high maternal expression in amphioxus eggs and cleavage-stage embryos. In Smo mutants, Pou4 and Pax2/5/8 expression at the primordial oral site is not altered before mouth opening. Conclusions Based on these results and our previous study, we conclude that Hh signal is necessary for amphioxus mouth formation and that the Hh-mediated regulation of mouth development is specific to the mouth. Our data suggest that Hh signaling regulates mouth formation in the amphioxus in a similar way as that in vertebrates, indicating the conserved role of Hh signaling in mouth formation.

Leptodactylus vastus (LEPTODACTYLIDAE) predation on an endemic frog, and a compilation of its diet

Diet composition constitutes basic information on the natural history of the species. Despite the amount of data acquired in the last years, much remains to be known specially for geographically widespread species. Here we compiled the available dietary items of Leptodactylus vastus and report the first predation event upon Rupirana cardosoi by a juvenile L. vastus. The fact these species are syntopic in the region probably resulted in this novel predation event. Different from previous L. vastus predation observations, the specimens we observed do not present a striking difference in body size, but L. vastus was able to almost swallow L. cardosoi, coherent with findings that mouth size is related to prey selection in anurans. Also, our literature review showed that L. vastus is a generalist and opportunistic predator, that prey upon small vertebrates (Amphibia, Squamata, and Mammalia).

Korelasi Panjang Berat Ikan Buntal Pisang Tetraodon lunaris Linnaeus, 1758 (Actinopterygii : Tetraodontidae) di Perairan Pati, Jawa Tengah

Perairan Pati mempunyai kekayaan sumberdaya jenis ikan yang beragam jenisnya. Salah satu hasil tangkapannya adalah Ikan Buntal Pisang (Tetraodon lunaris). Ikan Buntal Pisang memiliki bentuk badan membulat dan ukuran mulut yang kecil dengan moncongnya yang tumpul dan memiliki racun yang disebut tetrodotoksin (TTX). Namun Ikan Buntal Pisang memiliki kandungan gizi yang cukup tinggi dan sebagian masyarakat Pati mengolah ikan ini menjadi ikan asin. Penelitian ini didasarkan pada hasil tangkapan Ikan Buntal Pisang yang didaratkan di PPI Banyutowo oleh nelayan yang melakukan penangkapan di perairan Pati. Penelitian ini bertujuan untuk mengetahui nilai hubungan panjang berat Ikan Buntal Pisang yang berada di perairan Pati. Penelitian ini dilakukan dengan metode penelitian deskriptif, dimana pengambilan sampling berdasarkan metode pertimbangan (purposive sampling method). Penelitian dilaksanakan bulan Februari – April 2016 di PPI Banyutowo. Materi yang digunakan adalah 360 sampel Ikan Buntal Pisang. Sampling Ikan Buntal Pisang dilakukan sebanyak 3 kali yaitu 13 Februari, 12 Maret, dan 9 April 2016. Analisa data berupa analisis hubungan panjang berat Ikan Buntal Pisang. Hasil penelitian menunjukan pertumbuhan Ikan Buntal Pisang pada bulan Februari – April 2015 bersifat allometrik positif yang memiliki nilai slope (b) sebesar 3,30. Pati waters has a rich variety of fish species. One of the catches is Green Rough-Backed Puffer (Tetraodon lunaris). Green Rough-Backed Puffer have a rounded body shape and small mouth size with a blunt snout and a poison called tetrodotoxin (TTX). But this fish has a high nutritional content and some Pati people process this fish into salted fish. This research is based on the catch of Green Rough-Backed Puffer landed in PPI Banyutowo by fishermen who make arrests in the waters of Pati. This study aims to determine the value of the long weight relationship of Green Rough-Backed Puffer in the waters of Pati. This research was conducted with descriptive research method, where sampling was taken based on the method of consideration purposive sampling method. The study was conducted in February - April 2016 at PPI Banyutowo. The material used was 360 samples of Green Rough-Backed Puffer. Sampling of Green Rough-Backed Puffer was carried out 3 times, namely February 13, March 12, and April 9, 2016. Analysis of the data was in the form of an analysis of the long weight relationship of Green Rough-Backed Puffer. The results showed that the growth of Green Rough-Backed Puffer in February - April 2015 was positive allometric which had a slope value (b) of 3,30.

Bite size ofCaenorhabditis elegansregulates feeding, satiety and development on yeast diet

ABSTRACTIn the wild, the soil dwellingnematode Caenorhabditis elegansprimarily feeds on microbes which are abundant in rotting vegetation. Recent published studies showthat several Gram-positive and Gram-negative bacterial populations predominantly constitutes theC. elegansgut microbiome but surprisingly lack any yeast species. Here, we show thatC. elegansdisplay low satiety on yeast diet ofCryptococcus neoformans, C. laurentiiorS. cerevisiae. We found that average size of budding yeast cells is much larger thanE. colicells. Yeast cells also cause pharyngeal obstruction, diminished feeding, and lower level of neutral lipids in adultC. elegans. Using scanning electron microscopy, we show that the mouth size ofC. eleganslarvae is smaller than average yeast cell. The larvae have no detectable yeast in their alimentary canal and they undergo delayed development on yeast diet. We propose that microbial cell size or bite size could be one of the crucial factors in regulation of feeding inC. elegans.IMPORTANCEThe microbiome inC. elegansgut is composed of diverse genera of bacteria but it lacks yeast and other fungi. In this study, we provide evidence that yeast cell size is bigger than the mouth size ofC. eleganslarvae. We propose that “bigger than the bite’’ size of yeast cells is one possible reason for low satiety on yeast diet, reduced feeding, lower stored lipids and delayed development. The bite size threshold imposed byC. elegansmouth can, partly, explain absence of yeast inC. elegansnative gut microbiome and “bite size’’ can be studied further as a determinant of microbiome diversity in other animals.

Diet of the toad Rhinella icterica (Anura: Bufonidae) from Atlantic Forest Highlands of southeastern Brazil

In this study, we present some information of the regarding throphic niche from the anuran toad Rhinella icterica living in high altitudes above 2000 m a.s.l. from a habitat of the Atlantic Forest Biome - the Altitude Fields in the Itatiaia National Park. We found 150 prey items in toad stomachs, belonging to five prey types, as well as skin remains and some remains of plant material. The index of relative importance indicated that most important prey types were beetles and ants, these last composing 70% of the diet numerically and the trophic niche breadth (B) was 1.81. The relatively low diversity of prey types we recorded in the diet of R. icterica of Itatiaia and numerically dominated by ants suggests some preference for this item. We do not found significant relationship between the toad measurements with the preys' measurements. We concluded that R. icterica toads at the highlands of Itatiaia feeds on arthropods, mainly ants and coleopterans and that the high consumption of preys with relatively small and similar size as ants in the diet prevents an expected relationship among frog body or mouth size and prey volume and size.