A Protein-trap allele reveals roles for Drosophila ATF4 in photoreceptor degeneration, oogenesis and wing development

Metazoans have evolved various quality control mechanisms to cope with cellular stress inflicted by external and physiological conditions. ATF4 is a major effector of the Integrated Stress Response (ISR), an evolutionarily conserved pathway that mediates adaptation to various cellular stressors. Loss of function of Drosophila ATF4, encoded by the gene cryptocephal (crc), results in lethality during pupal development. The roles of crc in Drosophila disease models and in adult tissue homeostasis thus remain poorly understood. Here, we report that a protein-trap MiMIC insertion in the crc locus generates a crc-GFP fusion protein that allows visualization of crc activity in vivo. This allele also acts as a hypomorphic mutant that uncovers previously unknown roles for crc. Specifically, the crc protein-trap line shows crc-GFP induction in a Drosophila model for Retinitis Pigmentosa (RP). This crc allele renders flies more vulnerable to amino acid deprivation and age-dependent retinal degeneration. These mutants also show defects in wing veins and oocyte maturation. Together, our data reveal previously unknown roles for crc in development, cellular homeostasis and photoreceptor survival.

Diversity of ants in Aarey Milk Colony, Mumbai, India

Aarey Milk Colony (AMC) is 16km2 of forested area, acts as a buffer to the Sanjay Gandhi National Park, Mumbai. It has gardens, lakes, recreation spots, and a nursery. It also harbors 32 cattle farms, animal husbandry centers. Apart from urbanization and forest degradation, this forest harbors great biodiversity which includes the leopard as a top predator and also lesser-known species of amphibians, reptiles, and arthropods. Considering ants as important bio indicators and the vulnerability of AMC to development plans, a study on the diversity of ants was conducted from January 2016 to May 2016. Four methods were used for data collection of ants—pitfall trap, line-transect, quadrate, and all-out search. A total of 35 species under 24 genera under six subfamilies– Myrmicinae, Formicinae, Ponerinae, Dolichoderinae, Pseudomyrmecinae, and Cerapachyinae were recorded during this study. The Simpson’s diversity index (0.88) for the pit fall trap indicates that the diversity of ants in the AMC is fairly high. This increases the importance of this forest land which is presently facing a mass destruction of trees.

A protein-trap allele reveals roles for Drosophila ATF4 in photoreceptor degeneration, oocyte maturation and wing development

Metazoans have evolved various stress response mechanisms to cope with cellular stress inflicted by external and physiological conditions. The Integrated Stress Response (ISR) is an evolutionarily conserved pathway that mediates adaptation to cellular stress via the transcription factor, ATF4. Loss of function of Drosophila ATF4, encoded by the gene cryptocephal (crc), results in lethality during pupal development. The roles of crc in Drosophila disease models and adult tissue homeostasis thus remain poorly understood. Here, we report that a protein-trap MiMIC insertion in the crc locus generates a crc-GFP fusion protein that allows visualization of crc activity in vivo, and acts as a hypomorphic mutant that uncovers previously unknown roles for crc. Specifically, the crc protein-trap line shows crc-GFP induction in a Drosophila model for Retinitis Pigmentosa (RP). This crc allele renders photoreceptors more vulnerable to age-dependent retinal degeneration. crc mutant adult animals also show greater susceptibility to amino acid deprivation and reduced levels of known crc transcriptional targets. Furthermore, this mutant allele shows defects in wing veins and oocyte maturation, uncovering previously unknown roles for crc in the development of these tissues. Together, our data establish physiological and pathological functions of crc-mediated ISR in adult Drosophila tissues.

Fluorescent protein-based imaging and tissue-specific RNA-seq analysis of Arabidopsis hydathodes

Hydathodes are typically found at leaf teeth in vascular plants and are involved in water release to the outside. Although morphological and physiological analysis of hydathodes has been performed in various plants, little is known about the genes involved in hydathode function. In this study, we performed fluorescent protein-based imaging and tissue-specific RNA-seq analysis in Arabidopsis hydathodes. We used the enhancer trap line E325, which has been reported to express green fluorescent protein (GFP) at its hydathodes. We found that E325-GFP was expressed in small cells found inside the hydathodes (named E cells) that were distributed between the water pores and xylem ends. No fluorescence of the phloem markers pSUC2:GFP and pSEOR1:SEOR1-YFP was observed in the hydathodes. These observations indicate that Arabidopsis hydathodes are composed of three major components: water pores, xylem ends, and E cells. In addition, we performed transcriptome analysis of the hydathode using the E325-GFP line. Microsamples were collected from GFP-positive or -negative regions of E325 leaf margins with a needle-based device (~130 µm in diameter). RNA-seq was performed with each single microsample using a high-throughput library preparation method called Lasy-Seq. We identified 72 differentially expressed genes. Among them, 68 genes showed significantly higher and four genes showed significantly lower expression in the hydathode. Our results provide new insights into the molecular basis for hydathode physiology and development.

Heliconiini butterflies can learn time-dependent reward associations

For many pollinators, flowers provide predictable temporal schedules of resource availability, meaning an ability to learn time-dependent information could be widely beneficial. However, this ability has only been demonstrated in a handful of species. Observations of Heliconius butterflies suggest that they may have an ability to form time-dependent foraging preferences. Heliconius are unique among butterflies in actively collecting pollen, a dietary behaviour linked to spatio-temporally faithful ‘trap-line' foraging. Time dependency of foraging preferences is hypothesized to allow Heliconius to exploit temporal predictability in alternative pollen resources. Here, we provide the first experimental evidence in support of this hypothesis, demonstrating that Heliconius hecale can learn opposing colour preferences in two time periods. This shift in preference is robust to the order of presentation, suggesting that preference is tied to the time of day and not due to ordinal or interval learning. However, this ability is not limited to Heliconius , as previously hypothesized, but also present in a related genus of non-pollen feeding butterflies. This demonstrates time learning likely pre-dates the origin of pollen feeding and may be prevalent across butterflies with less specialized foraging behaviours.

Heliconiini butterflies can learn time-dependent reward associations

For many pollinators, flowers provide predictable temporal schedules of resource availability, meaning an ability to learn time-dependent information could be widely beneficial. However, this ability has only been demonstrated in a handful of species. Observational studies of Heliconius butterflies suggest that they may have an ability to form time-dependent foraging preferences. Heliconius are unique among butterflies in actively collecting and digesting pollen, a dietary behaviour linked to spatiotemporally faithful ‘trap-line’ foraging. Time-dependency of foraging preferences is hypothesised to allow Heliconius to exploit temporal predictability in alternative pollen resources, as well as contributing to optimal use of learnt foraging routes. Here, we provide the first experimental evidence in support of this hypothesis, demonstrating that Heliconius hecale can learn opposing colour preferences in two time periods. This shift in preference is robust to the order of presentation, suggesting that preference is tied to the time of day and not due to ordinal learning. However, we also show that this ability is not limited to Heliconius, as previously hypothesised, but is also present in a related genus of non-pollen feeding butterflies. This demonstrates that time learning pre-dates the origin of pollen-feeding and may be prevalent across butterflies with less specialized foraging behaviours.