Identification of astrocyte-like cells in an adult ascidian during regeneration of the central nervous system.

The mechanisms underlying regeneration of the central nervous system (CNS) following lesions have been studied extensively in both vertebrate and invertebrate models. To shed light on regeneration, ascidians, a sister group of vertebrates and with remarkable ability to regenerate their brains, constitute an appropriate model system. Glial cells have been implicated in regeneration in vertebrates; however, their role in the adult ascidian CNS regeneration is unknown. A model of degeneration and regeneration using the neurotoxin 3-acetylpyridine (3AP) in the brain of the ascidian Styela plicata was used to identify astrocyte-like cells and investigate their role. We studied the CNS of control ascidians (injected with artificial sea water) and of ascidians whose CNS was regenerating (1 and 10 days after the injection with 3AP). Our results show that the mRNA of the ortholog of glutamine synthetase (GS), a glial-cell marker in vertebrates, is increased during the early stages of regeneration. Confirming the identity of GS, the protein was identified via immunostaining in a cell population during the same regeneration stage. Last, a single ortholog of GS (GSII) is present in ascidian and amphioxus genomes, while two types exist in fungi, some invertebrates, and vertebrates, suggesting that ascidians have lost the GSI type. Taken together, our findings revealed that a cell population expressing glial-cell markers may play a role in regeneration in adult ascidians. This is the first report of astrocyte-like cells in the adult ascidian CNS, and contributes to understanding of the evolution of glial cells among metazoans.

The mlpt smORF gene is essential for digestive physiology and molting during nymphal stages in the kissing bug Rhodnius prolixus.

Chagas disease affects around 8 million people globally, with Latin America bearing approximately 10,000 deaths each year. Combatting the disease relies heavily on vector control methods, necessitating the identification of new targets. Within insect genomes, genes harboring small open reading frames (smORFs - < 100 amino acids) present numerous potential candidates. In our investigation, we elucidate the pivotal role of the archetypal smORF-containing gene, mille-pattes/polished-rice/tarsalless (mlpt/pri/tal), in the post-embryonic development of the kissing bug Rhodnius prolixus. Injection of double-stranded RNA targeting mlpt (dsmlpt) during nymphal stages yields a spectrum of phenotypes hindering post-embryonic growth. Notably, fourth or fifth stage nymphs subjected to dsmlpt do not undergo molting. These dsmlpt nymphs display heightened mRNA levels of JHAMT-like and EPOX-like, enzymes putatively involved in the juvenile hormone (JH) pathway, alongside increased expression of the transcription factor Kr-h1, indicating changes in the hormonal control. Histological examination reveals structural alterations in the hindgut and external cuticle of dsmlpt nymphs compared to control (dsGFP) counterparts. Furthermore, significant changes in the vector's digestive physiology were observed, with elevated hemozoin and glucose levels in the posterior midgut of dsmlpt nymphs. Importantly, dsmlpt nymphs exhibit impaired metacyclogenesis of Trypanosoma cruzi, the causative agent of Chagas disease, underscoring the crucial role of proper gut organization in parasite differentiation. Thus, our findings constitute the first evidence of a smORF-containing gene's regulatory influence on vector physiology, parasitic cycle, and disease transmission.

Identification of pre-flexion fish larvae from the western South Atlantic using DNA barcoding and morphological characters.

Knowledge on species composition is the first step necessary for the proper conservation and management of biological resources and ecologically relevant species. High species diversity and a lack of diagnostic characters for some groups can impose difficulties for taxonomic identification through traditional methodologies, and ichthyoplankton (fish larvae and eggs) are a good example of such a scenario. With more than 35.000 valid species of fishes worldwide and overall similar anatomies in early developmental stages in closely related groups, fish larvae are often hard to be identified at the species or even more encompassing taxonomic levels. To overcome this situation, molecular techniques have been applied, with different markers tested over the years. Cytochrome c oxidase I (COI) is the most commonly used marker and now has the broadest public reference libraries, providing consistent results for species identification in different metazoan studies. Here we sequenced the mitochondrial COI-5P fragment of 89 fish larvae collected in the Campos Basin, coastal southeastern Brazil, and compared these sequences with references deposited in public databases to obtain taxonomic identifications. Most specimens identified are species of the Blenniiformes, with Parablennius and Labrisomus the most frequently identified genera. Parablennius included two species (P. marmoreus and P. pilicornis), while Labrisomus included three species (L. cricota, L. conditus and L. nuchipinnis). Anatomy of these molecularly identified specimens were then analyzed with the intention of finding anatomical characters that might be diagnostically informative amongst the early development stage (pre-flexion) larvae. Ventral pigmentation patterns are proposed as useful markers to identify Labrisomus species. However, additional specimens are needed to confirm if the character holds stability through the geographic distribution of the species.

Spider's Silk as a Potential Source of Antibiotics: An Integrative Review.

Spiders produce webs, which are still a largely unexplored source of antibacterial compounds, although the reports of its application in the medical field. Therefore, this study aims to present an integrative review of the antibacterial activity of spider webs. The research was conducted using Google Scholar, Scielo, Web of Science, PubMed, ScienceDirect, Medline EBSCO, LILACS, and Embase. The inclusion criteria were original articles written in English that studied the antibiotic properties of the web or isolated compounds tested. The studies were compared according to the spider species studied, the type of web, treatment of the sample, type of antimicrobial test, and the results obtained. Nine hundred and seventy-three publications were found, and after applying the inclusion and exclusion criteria, sixteen articles were selected. Bacterial inhibition was found in seven studies against various species of bacteria such as Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Salmonella Typhi, Bacillus megaterium, Listeria monocytogenes, Acinetobacter baumannii, Streptococcus pneumoniae, Pasteurella multocida, and Bacillus subtilis. Additionally, there was no apparent relationship between the proximity of the spider species evaluated in the studies and the presence or absence of activity. Methodological problems detected may affected the reproducibility and reliability of the results in some studies, such as the lack of description of the web or microorganism strain, as well as the absence of adequate controls and treatments to sterilize the sample. Spider webs can be a valuable source of antibiotics; however, more studies are needed to confirm the real activity of the web or components involved.

Adrenoreceptor phylogeny and novel functions of nitric oxide in ascidian immune cells.

Nitric oxide (NO) is a simple molecule involved in many biological processes and functions in the cardiovascular, neural, and immune systems. In recent years, NO has also been recognized as a crucial messenger in communication between the nervous and immune systems. Together with NO, catecholamines are the main group of neurotransmitters involved in cross-talk between the nervous and immune systems. Catecholamines such as noradrenaline, can act on immune cells through adrenoreceptors (ARs) present on the cell surface, and NO can cross the cell membrane and interact with secondary messengers, modulating catecholamine production. Here, we analyzed the mutual modulation by noradrenaline and NO in Phallusia nigra immune cells for specific subtypes of ARs. We also investigated the involvement of protein kinases A and C as secondary messengers to these specific subtypes of ARs in the adrenergic signaling pathway that culminates in NO modulation, and the phylogenetic distribution of ARs in deuterostome genomes. This analysis provided evidence for single-copy orthologs of α1, α2 and ß-AR in ascidian genomes, suggesting that NO and NA act on a less diverse set of ARs in urochordates. Pharmacological assays showed that high levels of NO can induce ascidian immune cells to produce catecholamines. We also observed that protein kinases A and C are the secondary messengers involved in downstream modulation of NO production through an ancestral ß-AR. Taken together, these results provide new information on NO as a modulator of immune cells, and reveal the molecules involved in the signaling pathway of ARs. The results also indicate that ARs may participate in NO modulation. Finally, our results suggest that the common ancestor of urochordates possessed a less complex system of ARs required for immune action and diverse pharmacological responses, since the α-ARs are phylogenetically more related to D1-receptors than are the ß-ARs.