Major determinants of photoinduced cell death: Subcellular localization versus photosensitization efficiency

We present a study on whether and to what extent subcellular localization may compete favorably with photosensitization efficiency with respect to the overall efficiency of photoinduced cell death. We have compared the efficiency with which two cationic photosensitizers, namely methylene blue (MB) and crystal violet (CV), induce the photoinduced death of human cervical adenocarcinoma (HeLa) cells. Whereas MB is well known to generate singlet oxygen and related triplet excited species with high quantum yields in a variety of biological and chemical environments (i.e., acting as a typical type II photosensitizer), the highly mitochondria-specific CV produces triplet species and singlet oxygen with low yields, acting mostly via the classical type I mechanism (e.g., via free radicals). The findings described here indicate that the presumably more phototoxic type II photosensitizer (MB) does not lead to higher degrees of cell death compared to the type I (CV) photosensitizer. In fact, CV kills cells with the same efficiency as MB, generating at least 10 times fewer photoinduced reactive species. Therefore, subcellular localization is indeed more important than photochemical reactivity in terms of overall cell killing, with mitochondrial localization representing a highly desirable property for the development of more specific/efficient photosensitizers for photodynamic therapy applications. (C) 2011 Elsevier Inc. All rights reserved.

Degenerative process and cell death in salivary glands of Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae) semi-engorged female exposed to the acaricide permethrin

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Cocaine induces cell death and activates the transcription nuclear factor kappa-b in pc12 cells

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Cytotoxicity of Portland Cement with Different Radiopacifying Agents: A Cell Death Study

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Cell death and quantitative reduction of rests of Malassez according to age

Background and Objective: Rests of Malassez are clusters of epithelial cells that remain in the periodontal ligament throughout life. However, it has been reported that the number of these structures decreases with age, and some epithelial cells undergo apoptosis in rests of Malassez of young and adult rats. Therefore, the purpose of the present study was to investigate the incidence of epithelial cell death and the quantitative changes in the rests of Malassez in rat molars of different ages.Material and Methods: Fragments containing the upper molars of rats aged 29, 45 and 120 d were fixed, decalcified and embedded for analysis by light microscopy. In the sections stained by hematoxylin and eosin, the number of rests of Malassez and the number of nuclei of these epithelial structures were obtained. Moreover, the nuclei exhibiting typical features of cell death were also counted in each rest of Malassez. The terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) method for detection of cell death was also carried out.Results: In all groups examined, some rests of Malassez exhibited epithelial cell nuclei with typical features of apoptosis and some of them were also TUNEL positive. From 29 to 120 d of age in rats, the quantitative analysis showed a significant decrease in the total number of rests of Malassez in the cervical, middle and furcation regions of the periodontal ligament. Moreover, a significant decrease of epithelial cell nuclei was concomitant to an increase in the frequency of cell death in the oldest rats.Conclusion: These results suggest that epithelial cell death by apoptosis may be, at least in part, responsible for the reduction in the number of rests of Malassez according to age.

Cell death evaluation in benzo[a]pyrene-transformed human breast epithelial cells after microcell-mediated transfer of chromosomes 11 and 17

The incidence of apoptosis and nuclear instability, including the incidence of catastrophic death, were investigated in benzo[a]pyrene (BP)-transformed human breast epithelial cells (BP1-E cell line) after microcell-mediated transfer of chromosomes 11 and 17. Since the introduction of normal chromosomes 11 and 17 into tumorigenic human breast BP1-E cells reverts some of these cells' characteristics (especially those affected by microsatellite instabilities and loss of heterozygosity) those of parental non-transformed MCF-10F cells, it was expected that the cell death rates would also be affected by this treatment. The transfer of the mentioned chromosomes, especially chromosome 17, to tumorigenic BP1-E cells increased the apoptotic ratios and decreased the nuclear instability ratios, thus showing that the microsatellite instability and loss of heterozygosity induced by BP in these chromosomes of MCF-10F cells affect the control of cell death mechanisms. (C) 2003 Elsevier B.V. All rights reserved.

In situ localization of heat-shock proteins and cell death labelling in the salivary gland of acaricide-treated honeybee larvae

The effects of the acaricides, rotenone and oxalic acid (OA) on salivary glands of honeybee larvae were evaluated. Immunohistochemical methods were used to detect cell death and heat-shock protein (HSP70 and 90) localizations. Heat-shock proteins (HSP70 and 90) were localized in the cytoplasm and/or the nuclei of secretory gland cells, both under stress and in normal conditions. In rotenone-treated larvae, there were no changes in the normal level of cell death and also there were no morphological alterations in the secretory cells. In the larvae treated with oxalic acid, the salivary gland showed varying degrees of morphological cellular alteration and an increase in the cell death level. The present data suggest that stress-induced HSP70 might have an antiapoptotic effect while the stress-induced HSP90 might have a chaperone function in the larval salivary glands.

Fipronil-induced cell death in salivary glands of Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae) semi-engorged females

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Markers of cell death in salivary glands of males of the tick Rhipicephalus sanguineus (Latreille, 1806) (Acari, Ixodidae)

The salivary glands of Rhipicephalus sanguineus males at stages: unfed (control), at day seven post-attachment, and at days three and seven post-detachment from the host were examined using methods of enzymatic analysis and cell viability. At these stages of feeding, different staining patterns were observed in the cells of type IV, III, II and I acini, which were affected by degeneration in this sequence. Acid phosphatase reaction was inversely proportional to that of ATPase, while ATPase reaction was proportional to membrane integrity.Salivary gland cells of unfed males exhibited intact nucleus and plasma membrane, suggesting that the acid phosphatase detected may participate in the normal physiology of acini. In males at day seven post-attachment, intact membranes were observed in almost all types of acini, as well as stronger reaction for acid phosphatase, nuclear changes, and decrease in ATPase reaction, changes associated with the degenerative process. At days three and seven post-detachment degeneration progress, being observed loss of membrane integrity, nuclear changes, prominent decrease in ATPase reaction, and an increase in acid phosphatase reaction in the first case and a decreased of it at day seven post-detachment from the host. During cell death, alterations occurred in the following sequence: a) nuclear changes, b) loss of ATPase reaction, c) loss of integrity of the plasma membrane, and d) increase of acid phosphatase. The latter might be associated with the late degradation of cytoplasmic remnants, characterizing the process of cell death in glands of R. sanguineus males as atypical or non-classic apoptosis. (C) 2008 Elsevier B.V. All rights reserved.

Mitosis and cell death in the optic lobes of workers, queens and drones of the honey bee (Apis mellifera) during metamorphosis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Spontaneous germ cell death by apoptosis in epididymis of the adult bat Artibeus lituratus

Many factors can lead cells to apoptosis during the various stages of cell life. This study was undertaken to characterize germ cell death in the epididymis of the adult Artibeus lituratus by histochemical and immunohistochemical techniques using light microscopy and transmission electron microscopy. The results showed that cells with a nuclear phenotype and ultrastructural characteristics of chromatin compaction were common in apoptosis. The Apoptag test confirmed that the suspected cells were apoptotic. It is suggested that immature germ cells, when released from the germinative epithelium, may be directed towards the epididymis instead of being disposed of in the testicle. Furthermore, intact immature cells can leave the testicle in the initial phases of apoptosis and complete this phenomenon in the epididymis.

A new nucleolar body appears in Drosophila saltans salivary gland cells before histolysis, in programmed cell death

The salivary glands of Drosophila saltans ( saltans group, saltans subgroup) analyzed in an advanced stage of programmed cell death showed the appearance of a single, round, nucleolar corpuscle inside the highly altered nucleus of every gland cell, at a time during which the integrity of the original nucleolus was already lost and the original nucleolar material apparently disappeared. In the same nuclei, which already had also lost the characteristic chromosome structure, some delicate chromosome threads were maintained. In many cells, the new nucleolar corpuscle and these chromosome threads are associated. These findings are novel. However, the hypothesis put forward concerning their meaning remains dependent on other studies.

Cell death in ovarioles causes permanent sterility in Frieseomelitta varia worker bees

Frieseomelitta varia worker bees do not lay eggs even when living in queenless colonies, a condition that favors ovary development and oviposition in the majority of highly social bees. The permanent sterility of these worker bees was initially attributed to a failure in ovary morphogenesis and differentiation. Using transmission electron microscopy we found that at the beginning of the pupal phase the ovaries of F. varia workers are formed by four ovarioles, each of them composed of 1) a terminal filament at the apex of the ovarioles, containing juxtaposed and irregularly shaped cells, 2) a germarium with clusters of cystocytes and prefollicular cells showing long cytoplasmic projections that envelop the cystocyte clusters, 3) fusiform interfollicular and basal stalk precursor cells, and 4) globular, irregularly contoured basal cells with large nuclei. However, during the pupal phase an accentuated and progressive process of cell death takes place in the ovarioles. The dying cells are characterized by large membrane bodies, electron-dense apoptotic bodies, vacuoles, vesiculation, secondary lysosomes, enlarged rough endoplasmic reticulum cisternae, swollen mitochondria, pycnotic nuclei, masses of chromatin adjacent to the convoluted nuclear envelope, and nucleoli showing signs of fragmentation. Cell death continues in ovarioles even after the emergence of the workers. Once they become nurse bees, the ovaries have become transformed into a cell mass in which structurally organized ovarioles can no longer be identified. In F. varia workers, ovariole cell death most certainly is part of the program of caste differentiation.

Programmed cell death in salivary glands of Drosophila arizonae and Drosophila mulleri

Programmed cell death (PCD) in insect metamorphosis assumes a great diversity of morphology and controlling processes that are still not well understood. With the objective of obtaining information about the PCD process, salivary glands of Drosophila arizonae and D. mulleri were studied during larval-pupal development. From the results, it can be concluded that the type of the PCD that occurs in these organs is morphologically typical of apoptosis (formation of apoptotic nuclei, followed by fragmentation into apoptotic bodies). Histolysis happens in both species, between 22 and 23 h after pupation. There were no significant differences between the species studied. Apoptosis does not occur simultaneously in all cells. Cytoplasmic acid phosphatase activity gradually increases during development, suggesting the existence of acid phosphatases that are only expressed during the apoptotic stage. Twenty hours after pupation, salivary glands already show biochemical alterations relative to nuclear permeability such as acidification, possibly due to the fusion of lysosomes with the nucleus a few hours before apoptosis. Autophagy seems to act together with apoptosis and has a secondary role in cell death. ©FUNPEC-RP.

Canine transmissible venereal tumors: Aspects related to programmed cell death

Canine transmissible venereal tumor (CTVT) is a neoplasm transmitted by the physical transfer of viable tumor cells by direct contact with injured skin and/or mucous tissue. These cells can transpose across histocompatibility barriers into unrelated hosts. This review focuses on the biology of apoptosis and the interaction of proteins involved in this process, as well as p53, p63 and the antiapoptotic protein Bcl-2. As such, this disease offer unique opportunity to study the biology of transplantable tumours and the interaction of proteins involved in apoptosis process and the prognosis of CTVT.