Neochloris aquatica induces larval mortality, molting defects, and unstable flightless adults in the Asian tiger mosquito.

The Asian tiger mosquito, Aedes albopictus, is a highly invasive and aggressive species capable of transmitting a large number of etiological agents of medical and veterinary importance, posing a high risk for the transmission of emerging viruses between animals and humans. In this work, we evaluated the mosquitocidal activity of Neochloris aquatica against A. albopictus throughout its development and analyzed whether this effect was potentiated when the microalga was cultivated under stress conditions due to nutrient deprivation. Our results suggest that N. aquatica produces metabolites that have negative effects on these insects, including larval mortality, interruption of pupal development, and incomplete emergence of adults when fed on microalgae in the larval stages. When microalgae were cultured under stress conditions, an increase in molting defects was recorded, and the number of healthy adults emerged drastically decreased. Histological studies revealed severe signs of total disintegration of different tissues and organs in the thorax and abdomen regions. The muscles and fat bodies in the midgut and foregut were severely distorted. In particular, larval intestinal tissue damage included vacuolization of the cytoplasm, destruction of brush border microvilli, and dilation of the intercellular space, which are distinctive morphological characteristics of apoptotic cells. Evidence suggests that N. aquatica produces metabolites with mosquitocidal effects that affect development and, therefore, the ability to vector etiological agents of medical and veterinary importance.

Short-Term In Vivo Response to Anodized Magnesium Alloy as a Biodegradable Material for Bone Fracture Fixation Devices.

Biodegradable materials based on magnesium alloys have a huge potential for bone fracture fixation devices due to their adequate mechanical properties and biocompatibility. However, their fast degradation and the consequent liberation of hydrogen gas at the initial stages of implantation is the major limitation for their use. In this study, the AZ91D magnesium alloy was surface treated by an environment-friendly, nontoxic, and low-cost anodizing process and the early in vivo response was studied in a rat transcortical model. Adequate maturation of woven bone around implants-detected at day 7 post implantation-to lamellar bone was observed from day 15. Lamellar bone after 15 and 30 days of implantation presented similar volume, mineralization pattern, mineral to protein content, and estimated bone maturity between anodized AZ91D and polylactic acid (control) implants. Histology observation showed neither release of hydrogen bubbles in the region closed to the anodized AZ91D implant nor systemic effects on liver, kidney, and spleen. Thus, anodizing of AZ91D in the conditions stated here induced an adequate short-term in vivo response, which postulates their use as potential biodegradable fracture fixation devices for bone healing.

Evaluation of annealed titanium oxide nanotubes on titanium: From surface characterization to in vivo assays.

The entire route from anodic oxidation and surface characterization, including in vitro experiments and finally in vivo osseointegration assays were performed with the aim to evaluate nanotubular and crystalline annealed titanium oxides as a suitable surface for grade 2 titanium permanent implants. Polished titanium (T0) was compared with anodized surfaces obtained in acidic media with fluoride, leading to an ordered nanotubular structure of titanium oxide on the metal surface, characterized by tube diameter of 89 ± 24 nm (Tnts). Samples were thermally treated in air (TntsTT) to increase the anatase crystalline phase on nanotubes, with minor alteration of the structure. Corrosion tests were performed to evaluate the electrochemical response after 1, 14, and 28 days of immersion in simulated body fluid. Based on the in vitro results, heat-treated titanium nanotubes (TntsTT) were selected as a promissory candidate to continue with the osseointegration in vivo assays. The in vivo results showed no major improvement in the osseointegration process when compared with untreated Ti after 30 days of implantation and there also was a lower increase in the development of new osseous tissue.

Effect of anodized zirconium implants on early osseointegration process in adult rats: a histological and histomorphometric study.

Since surface plays a key role in bioactivity, the response of the host to the biomaterial will determine the success or failure of the prosthesis. The purpose of this study is to make an exhaustive analysis of the histological and histochemical characteristics of new bone tissue around Zr implants anodized at 60 V (Zr60) supported by histomorphometric methods in a rat model. Fibrous tissue was observed around the control implants (Zr0) and osteoblasts were identified on the trabeculae close to the implantation site that showed typical cytological characteristics of active secretory cells, regardless of the surface condition. The histomorphometrical analysis revealed a significant increase in cancellous bone volume, trabecular thickness and in trabecular number together with a decrease in trabecular separation facing Zr60. TRAP staining showed that there was a relative increase in the number of osteoclasts for Zr60. In addition, a larger number of osteoclast with a greater number of nuclei were detected in the tibiae for Zr60. This research demonstrated that the new bone microarchitecture in contact with Zr60 is able to improve the early stages of the osseointegration process and consequently the primary stability of implants which is a crucial factor to reduce recovery time for patients.

Analysis of glycoconjugates and morphological characterization of the descending colon and rectum of the plains viscacha, Lagostomus maximus.

Herbivores exhibit specializations at the intestinal level that facilitate the bacterial fermentation. The available information on the digestive physiology of Lagostomus maximus makes this rodent an interesting model to evaluate morpho-functional adaptations to herbivory. The general objective of this work was centered on the study of the morphology and histochemistry of the descending colon and rectum of L. maximus. To do so, a comparative analysis of the morphology, ultrastructure and glycosylation pattern of both anatomical regions was carried out. Histochemical results revealed that in both sectors of the large intestine, there are goblet cells with different glycosylation pattern within a morphologically homogeneous cell population. The main difference between both intestinal segments lay in the fact that the most distal region of the large intestine showed a greater proportion of sialomucins, characterized by being slightly O-acetylated. Further specific differences were revealed by lectin histochemistry. These data allowed to perform a functional interpretation of the cell types and secreted substances, thus contributing to a better understanding of the role of mucins in the intestinal tract functioning.

The colonic groove of the plains viscacha (Lagostomus maximus): Histochemical evidence of an abrupt change in the glycosylation pattern of goblet cells.

The ascending colon of most rodent species shows a longitudinal colonic groove that works as a retrograde transport pathway for a mixture of bacteria and mucus toward the cecum. We describe the morphology and glycosylation pattern of the colonic groove of Lagostomus maximus to analyze the role of mucins in this anatomical feature. We also studied the distribution pattern of the interstitial cells of Cajal (ICC) to evaluate their regulatory influence on gut motility. The groove originated near the cecocolic junction and extended along the mesenteric side of the ascending colon, limited at both ends by nonpapillated ridges. These ridges divided the lumen of the ascending colon into two compartments: a narrow channel and a large channel, called the groove lumen and the main lumen, respectively. The histochemical analysis showed differences in the glycosylation pattern of the goblet cells inside and outside the groove. Unlike the mucosa lining the main lumen of the colon, the groove was rich in goblet cells that secrete sulfomucins. The PA/Bh/KOH/PAS technique evidenced an abrupt change in the histochemical profile of goblet cells, which presented a negative reaction in the groove and a strongly positive one in the rest of the colonic mucosa. The anti-c-kit immunohistochemical analysis showed different ICC subpopulations in the ascending colon of L. maximus. Of all types identified, the ICC-SM were the only cells located solely within the colonic groove.

Comparative Analysis of the Morphology, Ultrastructure, and Glycosylation Pattern of the Jejunum and Ileum of the Wild Rodent Lagostomus maximus.

Morphological and histochemical analyses were performed to characterize the histology, ultrastructure, and glycosylation pattern of the jejunum and ileum of the wild rodent Lagostomus maximus. Enterocytes, goblet cells, Paneth cells, and enteroendocrine cells were identified in both intestinal epithelia. Two morphological types of enterocytes were identified only in the ileum based on their cytoplasm electron density. Although the histological and ultrastructural examination showed that the epithelia of both anatomical regions were morphologically similar, a certain specialization in their secretory products was evident. The glycosylation pattern of the jejunum and ileum was characterized in situ by histochemical and lectin histochemical methods. Histochemical results revealed the presence of carboxylated and sulfated gycoconjugates in both regions, although sulfomucins were clearly prevalent in the ileum. Sialic acid was highly O-acetylated and particularly abundant in the jejunum. The KOH/PA*/Bh/PAS technique evidenced a more intense histochemical reaction in the jejunal than in the ileum goblet cells, demonstrating a reduction of neutral mucin secretion in the distal small intestine. Further specific differences were revealed by lectin histochemistry. These data evidenced that the nature of mucus varies at different anatomical regions, probably adapted to physiological requirements.

Comparative analysis of the morphology and histochemistry of the duodenum of the coypu (Myocastor coypus bonariensis) during its prenatal and postnatal development.

The objective of this study focused on the comparative morphological and histochemical analysis of the duodenum of fetuses, juveniles and adult coypu (Myocastor coypus bonariensis), the major socioeconomic wildlife resource of Argentina. Histological and histochemical procedures for in situ characterization of glycoconjugates (GCs) were used. This study evidenced that fetal mucins differ histochemically in many respects from their adult counterparts. Only in fetuses from 90 days-post coitus (dpc) glycogen-rich sites were observed throughout the duodenal epithelium. The goblet cells appeared from 105 dpc and their secretory content varied considerably after birth. Duodenal glands presented scanty neutral and sulphated GCs in the 30-day juveniles; in adults the proportion of these GCs increased, and carboxylated and sialylated GCs were also observed. The results obtained in this work may be used in future studies to evaluate the effects of diet and intestinal pathologies in the glycosylation pattern of GCs. Also, knowledge of the normal glycoprofile of the duodenum of M. coypus bonariensis during its ontogenetic development may constitute a basis for the study of this organ in other Hystricognathi rodents.

Surface ultrastructure of the gills of Odontesthes bonariensis (Valenciennes, 1835)(Teleostei: Atheriniformes) from a temperate shallow lake / Estudio ultraestructural de las branquias de Odontesthes bonariensis (Valenciennes, 1835) (Teleostei: Atheriniformes) de un lago somero templado

We studied the gill epithelium of juveniles of Odontesthes bonariensis using scanning electron microscopy with a particular interest in the relationship between cell morphology and the different functional aspects of gills. The specimens used were collected in Laguna de los Padres, Buenos Aires Province, Argentina. The gill filaments or primary lamellae are arranged in two rows along the convex outer face of the gill arch forming the anterior and posterior hemibranchiae. On its concave inner face, each arch supports two rows of gill rakers forming the pharyngeal region wall. The primary lamellae are lined by a stratified epithelium made up of polygonal cells with well-defined outlines and cell membrane microfolds. Several mucous and chloride cells were observed in the primary lamellae. The epithelial cells of the secondary lamellae have ill-defined outlines and few microfolds. Both the arches and gill rakers are covered by a stratified epithelium of polygonal cells, among which mucous cells and taste corpuscles are abundant. The ultrastructural analysis of gills of O. bonariensis contributes to the advancement of knowledge of the organ histophysiology and of future histopathological studies.

Se estudió el epitelio branquial de juveniles de Odontesthes bonariensis utilizando microscopía electrónica de barrido con un interés particular en la relación entre la morfología celular y los distintos aspectos funcionales de las branquias. Los ejemplares utilizados fueron colectados en la Laguna de los Padres, Provincia de Buenos Aires, Argentina. Los filamentos branquiales o laminillas primarias están dispuestos en dos filas a lo largo de la cara exterior convexa del arco branquial formando las hemibranquias anterior y posterior. En su cara interior cóncava, cada arco sostiene dos hileras de branquiespinas que forman la pared de la región faríngea. Las laminillas primarias están revestidas por un epitelio estratificado constituido por células poligonales con contornos bien definidos y micropliegues de la membrana celular. Se observaron numerosas células clorhídricas y mucosas en las laminillas primarias. Las células epiteliales de las laminillas secundarias tienen contornos poco definidos y escasos micropliegues. Tanto los arcos como las branquiespinas están cubiertos por un epitelio estratificado de células poligonales, entre las cuales hay abundantes células mucosas y corpúsculos gustativos. El análisis ultraestructural de las branquias de O. bonariensis proporciona información para avanzar en el conocimiento de la histofisiología del órgano y para realizar futuros estudios histopatológicos.