Glial granules contain germline proteins in the Drosophila brain, which regulate brain transcriptome

Membraneless RNA-protein granules play important roles in many different cell types and organisms. In particular, granules found in germ cells have been used as a paradigm to study large and dynamic granules. These germ granules contain RNA and proteins required for germline development. Here, we unexpectedly identify large granules in specific subtypes of glial cells (“glial granules”) of the adult Drosophila brain which contain polypeptides with previously characterized roles in germ cells including scaffold Tudor, Vasa, Polar granule component and Piwi family proteins. Interestingly, our super-resolution microscopy analysis shows that in the glial granules, these proteins form distinct partially overlapping clusters. Furthermore, we show that glial granule scaffold protein Tudor functions in silencing of transposable elements and in small regulatory piRNA biogenesis. Remarkably, our data indicate that the adult brain contains a small population of cells, which express both neuroblast and germ cell proteins. These distinct cells are evolutionarily conserved and expand during aging suggesting the existence of age-dependent signaling. Our work uncovers previously unknown glial granules and indicates the involvement of their components in the regulation of brain transcriptome.

Eimeria spp. (Apicomplexa: Eimeriidae) in Didelphis aurita Wied-Neuwied, 1826 (Didelphimorphia: Didelphidae) and description of a new species infecting this opossum

Didelphis aurita Wied-Neuwied, 1826 is a marsupial well adapted to anthropogenic activity and commonly found in urban areas of Brazil. Among the gastrointestinal parasites found in this opossum, protozoa of the genus Eimeria are frequently detected. This study investigated the biodiversity of Eimeria species infecting D. aurita in Southeastern Brazil, and provides morphological data on a newly discovered species of Eimeria. From January to June 2019, 43 D. aurita were captured, and their fecal samples were collected and evaluated by salt flotation; positive samples were allowed to sporulate in 2.5% potassium dichromate (K2Cr2O7), and detailed morphological measurements were performed to determine the species present. Thirty-two of forty-three (74.4%) opossums were infected with from one to five Eimeria spp. Four of the eimerians were described and named previously by others: Eimeria auritanensis, Eimeria caluromydis, Eimeria gambai, and Eimeria philanderi. Additionally, sporulated oocysts of a species new to science were detected. Oocysts of this new Eimeria species are spheroidal to subspheroidal, 21.7 × 20.7 (20-23 × 19-23), length/width (L/W) ratio 1.05, with a highly refractile polar granule, but lacking a micropyle and oocyst residuum. Sporocysts are ovoidal, 10.6 × 8.0 (9-12 × 7-9), L/W ratio 1.3, with a small, Stieda body and a sporocyst residuum of diffuse granules. Of the infected opossums, 5/32 (16%) were infected with only one Eimeria sp., 6/32 (19%) with two, 15/32 (47%) with three, 5/32 (16%) with four and 1/32 (3%) with five Eimerians.

A new coccidian parasite (Apicomplexa: Eimeriidae: Eimeria) from the southern black racer, Coluber constrictor priapus (Reptilia: Ophidia: Colubridae) from Arkansas, USA

Between April 2012 and October 2017, 18 southern black racers,Coluber constrictor priapus, were collected from nine counties of Arkansas (n= 13) and McCurtain County, Oklahoma (n= 5) and their faeces examined for coccidian parasites. One of 18 (6%)C. c. priapusharboured an eimerian that we describe here as new. Oocysts ofEimeria dunnisp. nov. were subspheroidal with a lightly pitted bi-layered wall measuring L × W 24.0 × 21.1 and L/W ratio of 1.2. A micropyle was absent but an oocyst residuum and polar granule were present. Sporocysts were ovoidal and measured 11.9 × 8.1 with L/W of 1.5. A Stieda body was present but substieda and parastieda bodies were absent. The sporocyst residuum was composed of medium-sized granules aligned along perimeter of sporocyst or in a dispersed mass. This represents the first valid eimerian reported from the southern black racer.

Sequential regulation of maternal mRNAs through a conserved cis-acting element in their 3’UTRs

Maternal mRNAs are synthesized during oogenesis to initiate the development of future generations. Some maternal mRNAs are determinants of somatic or germline fate and must be translationally repressed until embryogenesis. However, the translational repressors themselves are also temporally regulated. We use polar granule component (pgc), a Drosophila maternal mRNA, as a model system to ask how maternal mRNAs are repressed while the regulatory landscape is continually shifting. pgc, a potent transcriptional silencer and germline determinant, is translationally regulated throughout oogenesis. We find that the 3’UTR of pgc mRNA contains a conserved ten-nucleotide sequence that is bound by different conserved RNA binding proteins (RBPs) at different stages of oogenesis to continuously repress translation except for a brief expression in the stem cell daughter. Pumilio (Pum) binds to this sequence in undifferentiated and early differentiating oocytes and recruits other temporally restricted translational regulators to block pgc translation. After differentiation, Pum levels diminish and Bruno (Bru) levels increase, allowing Bru to bind the same 3’UTR sequence and take over translational repression of pgc mRNA. We have identified a class of maternal mRNAs regulated during oogenesis by both Pum and Bru, including Zelda, activator of the zygotic genome, which contain this core 10-nt regulatory sequence. Our data suggests that this hand off mechanism is more generally utilized to inhibit translation of maternal mRNAs during oogenesis.

Avispora mochogalegoi n. sp. (Apicomplexa: Sarcocystidae) in the little owl, Athene noctua (Strigiformes: Strigidae), in mainland Portugal

The little owl Athene noctua (Scopoli, 1769) is a small raptor that is widely distributed from northern to southern Portugal and several other countries in Europe, Asia and North Africa, and which has been introduced into New Zealand. In the current study, 18 fecal samples were collected from little owls kept at the Lisbon Center for Wild Animal Recovery, which is located in Monsanto Forest Park, Lisbon, Portugal. Twelve (67%) of them were found to be passing an undescribed species of Avispora in their feces. The oocysts of Avispora mochogalegoi n. sp. were ellipsoidal with a bilayered wall and measured 38.9 × 32.9 µm, with a shape index of 1.18. No micropyle, oocyst residuum or polar granule was present. The sporocysts were subspherical, measuring 21.1 × 20.1 µm. Stieda, sub-Stieda and para-Stieda bodies were absent. The sporocyst residuum was composed of a compact subspherical mass of granules. This is the fourth species of Avispora reported in Strigiformes.

Isospora albicollis (Apicomplexa: Eimeriidae) in thrushes Turdus spp. (Passeriformes: Turdidae), in southeastern Brazil

The aim of the present study was to report and describe Isospora albicollis Lainson and Shaw, 1989 parasitizing a white-necked thrush Turdus albicollis Vieillot, 1818 and a pale-breasted thrush Turdus leucomelas Vieillot, 1818 in two different localities: the Itatiaia National Park and Cacaria, in southeastern Brazil. The oocysts identified were ovoidal, 24.4 × 19.7 μm, with a smooth, bilayered wall, around 1.4 μm thick. Oocyst residuum was absent, but a micropyle and a polar granule were present. The sporocysts were ellipsoidal, 15.4 × 10.1 μm. The Stieda body was knob-like to rounded and the sub-Stieda body was prominent and wide. Sporocyst residuum was present, usually as a cluster of granules that appear to be membrane-bounded. The sporozoites were vermiform with one posterior refractile body and a centrally located nucleus. Besides recording the new host T. leucomelas, the identification of I. albicollis in the Itatiaia National Park and Cacaria, in southeastern Brazil, provide records of new localities for its parasitism, and reveals the wide distribution and dispersion of this coccidium in Brazil.

Caryospora peneireiroi n. sp. (Apicomplexa: Eimeriidae) in the common kestrel, Falco tinnunculus (Falconiformes: Falconidae), in mainland Portugal

The common kestrel Falco tinnunculus Linnaeus, 1758, is a widespread raptor, native in Europe, Asia and Africa, and vagrant in the Americas. In the current work, 27 fecal samples were collected from common kestrels kept in the Lisbon Center for Wild Animal Recovery, located at Monsanto Forest Park, Lisbon, Portugal. Five (19%) of them were found to be passing an undescribed species of Caryospora in their feces. The oocysts of Caryospora peneireiroi n. sp. were ellipsoidal with a bilayered wall and measured 47.1 × 37.6 µm with a shape index of 1.25. No micropyle, oocyst residuum or polar granule was present. The sporocysts were subspherical, measuring 25.1 × 24.3 µm. Stieda, sub-Stieda and para-Stieda bodies were absent. The sporocyst residuum was composed of many homogenous globules scattered throughout the periphery of the sporocyst. This is the fourth caryosporan species reported from F. tinnunculus.

Caryospora bigenetica (Apicomplexa: Eimeriidae) in South America: new hosts and distribution records

The coccidian Caryospora bigenetica was first described in the snake Crotalus horridus (Viperidae) from United States of America. This study represents the first record of the occurrence of C. bigenetica in snakes in South America. Feces were sampled between November 2013 and May 2014 from 256 wild snakes maintained in scientific breeding facilities in the states of Mato Grosso do Sul (MS; n = 214) and Rio de Janeiro (RJ; n = 42), Brazil. Caryospora bigenetica was found in 14 (5.6%) snakes, all belonging to the family Viperidae. Ten Bothrops moojeni and two Crotalus durissus from MS were infected. The coccidian was also found in one C. durissus and in one Bothrops jararacussu from the state of RJ. The oocysts were spherical with a double wall, the exterior lightly mammillated, striations apparent in transverse view, 13.0 µm (12 – 14); polar granule fixed in the internal wall. Sporocysts oval or pyriform, 10.0 × 8.0 µm (9 – 11 × 8 – 9); Stieda body discoid; sub-Stieda body present; sporocyst residuum present, formed by a group of spheroid bodies between sporozoites. This study increases the number of viperid hosts of C. bigenetica and expands the geographical distribution to South America.

A new species of Isospora (Apicomplexa: Eimeriidae) from eastern coachwhip, Coluber flagellum flagellum (Reptilia: Ophidia) from Oklahoma

Between June 2013 and August 2014, four eastern coachwhips, Coluber flagellum flagellum were collected from Arkansas (n = 2) and Oklahoma (n = 2) and their faeces examined for coccidian parasites. One (25%) harboured an isosporan that we describe here as new. Oocysts of Isospora kiamichiensis sp. n. were spheroidal to subspheroidal with a uni-layered wall and measured (length × width, L × W) 25.0 × 22.2 μm, with an L/W ratio of 1.1. A micropyle, oocyst residuum and polar granule were absent. Sporocysts were ovoidal, 13.9 × 9.4 μm, with an L/W ratio of 1.5. A pronounced, button-like Stieda body was present as well as a substieda body. A sporocyst residuum was present as dispersed granules. This is the first isosporan and fourth coccidian reported from eastern coachwhip snakes. In addition, a single oocyst of an unknown choleoeimerian was recovered from this host.