Astral Microtubules Are Dispensable for Pavarotti Localization During Drosophila Spermatogonial Mitoses.

We analysed here the dynamic of the kinesin-like Pavarotti (Pav) during male gametogenesis of wild-type and Sas4 mutant flies. Pav localizes to the equatorial region and the inner central spindle of late anaphase wild-type spermatogonia and displays a strong concentration at the midbody during late telophase. At metaphase of the first meiotic division, Pav shows widespread localization on the equatorial region of the spermatocytes.

Axonemal tubules in the distal sperm tail of Wolbachia-infected Drosophila simulans males contain ring-like intraluminal structures that persist after axoneme fragmentation.

Wolbachia are obligate intracellular alphaproteobacteria that enhance their spreading by altering the reproductive mechanisms of several invertebrates. Among the reproductive alterations, Wolbachia also causes cytoplasmic incompatibility that leads to embryo death when infected males are crossed with uninfected females, thus selecting infected females. However, the presence of Wolbachia has important fitness costs and infected Drosophila simulans males produce less sperm than their uninfected counterparts.

The cilium like region of the Drosophila bifurca spermatocyte: Elongation of a giant axoneme without intraflagellar transport.

The growth of the ciliary axonemes mainly depends on the evolutionary conserved intraflagellar transport (IFT) machinery. However, insect spermatocytes are characterized by cilium-like regions (CLRs) that elongate in the absence of IFT. It is generally believed that the dynamics of these structures relies on the free diffusion of soluble tubulin from the cytoplasm.

Induces Structural Defects Harmful to Riverside Spermiogenesis.

The relationship between cytoplasmic incompatibility and the obligate intracellular alphaproteobacteria has for a long time been reported. Although the molecular mechanisms responsible for this reproductive alteration are beginning to be understood, the effects of on germ cell structure and dynamics have not yet been fully investigated. We report here that the presence of in infected cysts of elongating spermatids is associated with major structural defects that become more evident in mature sperm.

Mob4 is essential for spermatogenesis in Drosophila melanogaster.

Gamete formation is essential for sexual reproduction in metazoans. Meiosis in males gives rise to spermatids that must differentiate and individualize into mature sperm. In Drosophila melanogaster, individualization of interconnected spermatids requires the formation of individualization complexes that synchronously move along the sperm bundles.

Generation of iPSC-derived human forebrain organoids assembling bilateral eye primordia.

Induced pluripotent stem cell-derived brain organoids enable the developmental complexities of the human brain to be deconstructed. During embryogenesis, optic vesicles (OVs), the eye primordium attached to the forebrain, develop from diencephalon. However, most 3D culturing methods generate either brain or retinal organoids individually.

Evidence for intraflagellar transport in butterfly spermatocyte cilia.

In the model organism insect Drosophila melanogaster short cilia assemble on spermatocytes that elaborate into 1.8 mm long flagella during spermatid differentiation. A unique feature of these cilia/flagella is their lack of dependence on intraflagellar transport (IFT) for their assembly.

Cell-to-Cell Interactions during Early Oogenesis: An Ultrastructural Analysis.

oogenesis requires the subsequent growth of distinct egg chambers each containing a group of sixteen germline cells surrounded by a simple epithelium of follicle cells. The oocyte occupies a posterior position within the germ cells, thus giving a distinct asymmetry to the egg chamber. Although this disposition is critical for the formation of the anterior-posterior axis of the embryo, the interplay between somatic and germ cells during the early stages of oogenesis remains an open question.

Management of patients with severe asthma: results from a survey among allergists and clinical immunologists of the Central Italy Inter-Regional Section of SIAAIC.

Background: Asthma, and severe asthma in particular, is often managed within a specialized field with allergists and clinical immunologists playing a leading role. In this respect, the National Scientific Society SIAAIC (Società Italiana di Allergologia, Asma ed Immunologia Clinica), structured in Regional and Inter-Regional sections, interviewed a large number of specialists involved in the management of this respiratory disease.

Methods: A survey entitled "Management of patients with asthma and severe asthma" based on 17 questions was conducted through the SIAAIC newsletter in 2019 thanks to the collaboration between GlaxoSmithKline S.

Early Drosophila Oogenesis: A Tale of Centriolar Asymmetry.

Among the morphological processes that characterize the early stages of Drosophila oogenesis, the dynamic of the centrioles deserves particular attention. We re-examined the architecture and the distribution of the centrioles within the germarium and early stages of the vitellarium. We found that most of the germ cell centrioles diverge from the canonical model and display notable variations in size.

Human brain organoids assemble functionally integrated bilateral optic vesicles.

During embryogenesis, optic vesicles develop from the diencephalon via a multistep process of organogenesis. Using induced pluripotent stem cell (iPSC)-derived human brain organoids, we attempted to simplify the complexities and demonstrate formation of forebrain-associated bilateral optic vesicles, cellular diversity, and functionality. Around day 30, brain organoids attempt to assemble optic vesicles, which develop progressively as visible structures within 60 days.

Sas-4 Colocalizes with the Ciliary Rootlets of the Sensory Organs.

The eye displays peculiar sensory organs of unknown function, the mechanosensory bristles, that are intercalated among the adjacent ommatidia. Like the other sensory organs, the mechanosensory bristles consist of a bipolar neuron and two tandemly aligned centrioles, the distal of which nucleates the ciliary axoneme and represents the starting point of the ciliary rootlets. We report here that the centriole associated protein Sas-4 colocalizes with the short ciliary rootlets of the mechanosensory bristles and with the elongated rootlets of chordotonal and olfactory neurons.

The Microtubule Cytoskeleton during the Early Spermiogenesis.

Sperm elongation and nuclear shaping in largely depends on the microtubule cytoskeleton that in early spermatids has centrosomal and non-centrosomal origins. We report here an additional γ-tubulin focus localized on the anterior pole of the nucleus in correspondence of the apical end of the perinuclear microtubules that run within the dense complex. The perinuclear microtubules are nucleated by the pericentriolar material, or centriole adjunct, that surrounds the basal body and are retained to play a major role in nuclear shaping.

Tissue specific requirement of Drosophila Rcd4 for centriole duplication and ciliogenesis.

Rcd4 is a poorly characterized Drosophila centriole component whose mammalian counterpart, PPP1R35, is suggested to function in centriole elongation and conversion to centrosomes. Here, we show that rcd4 mutants exhibit fewer centrioles, aberrant mitoses, and reduced basal bodies in sensory organs. Rcd4 interacts with the C-terminal part of Ana3, which loads onto the procentriole during interphase, ahead of Rcd4 and before mitosis.

Centrioles and Ciliary Structures during Male Gametogenesis in Hexapoda: Discovery of New Models.

Centrioles are-widely conserved barrel-shaped organelles present in most organisms. They are indirectly involved in the organization of the cytoplasmic microtubules both in interphase and during the cell division by recruiting the molecules needed for microtubule nucleation. Moreover, the centrioles are required to assemble cilia and flagella by the direct elongation of their microtubule wall.

The Singularity of the Drosophila Male Germ Cell Centriole: The Asymmetric Distribution of Sas4 and Sas6.

Drosophila spermatocytes have giant centrioles that display unique properties. Both the parent centrioles maintain a distinct cartwheel and nucleate a cilium-like region that persists during the meiotic divisions and organizes a structured sperm axoneme. Moreover, the parent centrioles are morphologically undistinguishable, unlike vertebrate cells in which mother and daughter centrioles have distinct structural features.

Doublefault protein coordinates multiple events during male meiosis by controlling mRNA translation.

During the extended prophase of gametogenesis, spermatocytes undergo robust gene transcription and store many transcripts in the cytoplasm in a repressed state, until translational activation of select mRNAs in later steps of spermatogenesis. Here, we characterize the Doublefault (Dbf) protein as a C2H2 zinc-finger protein, primarily expressed in testes, that is required for normal meiotic division and spermiogenesis. Loss of Dbf causes premature centriole disengagement and affects spindle structure, chromosome segregation and cytokinesis.

The midbody interactome reveals unexpected roles for PP1 phosphatases in cytokinesis.

The midbody is an organelle assembled at the intercellular bridge between the two daughter cells at the end of mitosis. It controls the final separation of the daughter cells and has been involved in cell fate, polarity, tissue organization, and cilium and lumen formation. Here, we report the characterization of the intricate midbody protein-protein interaction network (interactome), which identifies many previously unknown interactions and provides an extremely valuable resource for dissecting the multiple roles of the midbody.

The Microtubule-Depolymerizing Kinesin-13 Klp10A Is Enriched in the Transition Zone of the Ciliary Structures of .

The precursor of the flagellar axoneme is already present in the primary spermatocytes of . During spermatogenesis each primary spermatocyte shows a centriole pair that moves to the cell membrane and organizes an axoneme-based structure, the cilium-like region (CLR). The CLRs persist through the meiotic divisions and are inherited by young spermatids.

The male stem cell niche of Drosophila melanogaster: Interactions between the germline stem cells and the hub.

The Drosophila male stem cell niche is a well characterized structure in which a small cluster of somatic cells send self-renewal signals to neighbouring germ cells. Although the molecular information involved in the stem cell fate have been identified, much less is understand on the mechanisms driving their short-range specific release. Our ultrastructural analysis reveals distinct protrusions of the stem cell plasma membrane that interdigitate with membrane protrusions of the facing hub cells.

Plk1/Polo Phosphorylates Sas-4 at the Onset of Mitosis for an Efficient Recruitment of Pericentriolar Material to Centrosomes.

Centrosomes are the major microtubule-organizing centers, consisting of centrioles surrounded by a pericentriolar material (PCM). Centrosomal PCM is spatiotemporally regulated to be minimal during interphase and expands as cells enter mitosis. It is unclear how PCM expansion is initiated at the onset of mitosis.

A transient microtubule-based structure uncovers a new intrinsic asymmetry between the mother centrioles in the early Drosophila spermatocytes.

Parent centrioles are characterized in most organisms by individual morphological traits and have distinct asymmetries that provide different functional properties. By contrast, mother and daughter centrioles are morphologically undistinguishable during Drosophila male gametogenesis. Here we report the presence of previously unrecognized microtubule-based structures that extend into the peripheral cytoplasm of the Drosophila polar spermatocytes at the onset of the first meiosis and are positive for the typical centriolar protein Sas-4 and for the kinesin-like protein Klp10A.

The "transition zone" of the cilium-like regions in the Drosophila spermatocytes and the role of the C-tubule in axoneme assembly.

The fruit-fly Drosophila melanogaster harbours different types of ciliary structures: ciliary projections associated with neurons of type I and cilium-like regions (CLRs) found during male gametogenesis. The latter deserve particular attention since they are morphologically similar to vertebrate primary cilia and transform into the sperm axonemes during spermiogenesis. Although, all the centrioles are able to organize the CLRs, we found that the mother centriole docks first to the plasma membrane suggesting a new intrinsic functional asymmetry between the parent centrioles.

Gorab is a Golgi protein required for structure and duplication of Drosophila centrioles.

We demonstrate that a Drosophila Golgi protein, Gorab, is present not only in the trans-Golgi but also in the centriole cartwheel where, complexed to Sas6, it is required for centriole duplication. In addition to centriole defects, flies lacking Gorab are uncoordinated due to defects in sensory cilia, which lose their nine-fold symmetry. We demonstrate the separation of centriole and Golgi functions of Drosophila Gorab in two ways: first, we have created Gorab variants that are unable to localize to trans-Golgi but can still rescue the centriole and cilia defects of gorab null flies; second, we show that expression of C-terminally tagged Gorab disrupts Golgi functions in cytokinesis of male meiosis, a dominant phenotype overcome by mutations preventing Golgi targeting.