Diagnosis of acute graft-versus-host disease in the gastrointestinal tract of patients undergoing allogeneic hematopoietic stem cell transplantation. A descriptive and critical study of diagnostic tests

Introduction

Acute graft-versus-host disease (GVHD) is one of the major causes of morbidity and mortality in patients undergoing allogeneic hematopoietic stem cell transplantation (AHSCT) and has become the subject of several studies to understand and treat it.

Objective

This study does a descriptive analysis of the apoptotic index (AI) evaluation and intestinal permeability (IP) alterations in association with the clinical, endoscopic and histopathological data on patients undergoing AHSCT, with emphasis on acute intestinal graft-versus-host disease (GVHD) diagnosis.

Methods

Thirty-one patients were divided into two groups—one of patients with a clinical GVHD diagnosis and one of those without GVHD diagnosis.

Results

Thirteen deaths (41.9%) occurred during the study period, thereby reaffirming the severity of the alterations found in the patients. Fifteen patients subjected to 21 esophagogastroduodenoscopy procedures prior to D + 90 post-transplant had visible endoscopic alterations and 19 biopsies revealed histological alterations to the stomach and duodenum. Higher apoptotic indices, not reaching statistical significance, were observed in patients who died of graft versus host disease (GVHD), in the more acute forms of GVHD and where clinical GVHD was present. The intestinal permeability evaluation was performed on nine patients able to undergo it in the three proposed study periods, which showed alterations, some of which were pronounced even during pre-transplant and, therefore, the pre-conditioning phase.

Conclusion

Clinical judgment remains a fundamental tool in the diagnosis of GVHD. This study points to the known limitations of traditional diagnostic aids (endoscopy and histology) and points to new methods not usually employed in clinical practice.

Conidiobolomycosis in Sheep in Brazil

Conidiobolomycosis is reported in the state of Piauí, in the semiarid region of northeastern Brazil. Affected sheep had depression, weight loss, serous or mucohemorrhagic nasal discharge, and cranium-facial asymmetry from exophthalmos of 1 eye, generally with increased volume of the eyeball, keratitis, and corneal ulceration. At necropsy of 60 sheep, friable masses were observed in the posterior region of the nasal cavity, often destroying the ethmoturbinate bones. Frequently, the lesions invaded the nasal sinuses, cribiform plate, orbit, and brain. The masses were irregular, granular with moist surfaces, and soft and friable with white, yellow, or tan coloration. Dissemination of the lesion to lungs was observed in 27 sheep, to the brain in 26, to lymph nodes in 3, to the kidney in 2, and to the gallbladder and heart in 1. The microscopic examination showed granulomatous inflammation composed of central necrosis surrounded by lymphocytes, epithelioid and giant cells, and fibrous tissue. In all lesions, negatively stained structures representing hyphae were surrounded by Splendore-Hoeppli material. Coagulative necrosis, thrombosis, and vasculitis were also observed. Grocott methenamine silver stain showed 8–30-μm-thick hyphae, rarely septate or ramified, irregular in shape, and with black contoured wall, sometimes with bulbous dilatation in the extremities. On electron microscopy, the hyphae had a thick double wall surrounded by cellular remnants and an inflammatory exudate. Conidiobolus coronatus was isolated from the lesions of 6 sheep. Conidiobolomycosis is an important disease of sheep in the state of Piauí, and other regions of northeastern Brazil.

Gene-microbiota interactions contribute to the pathogenesis of inflammatory bowel disease

Inflammatory bowel disease (IBD) is associated with risk variants in the human genome and dysbiosis of the gut microbiome, though unifying principles for these findings remain largely undescribed. The human commensal Bacteroides fragilis delivers immunomodulatory molecules to immune cells via secretion of outer membrane vesicles (OMVs). We reveal that OMVs require IBD-associated genes, ATG16L1 and NOD2, to activate a noncanonical autophagy pathway during protection from colitis. ATG16L1-deficient dendritic cells do not induce regulatory T cells (T(regs)) to suppress mucosal inflammation. Immune cells from human subjects with a major risk variant in ATG16L1 are defective in T(reg) responses to OMVs. We propose that polymorphisms in susceptibility genes promote disease through defects in "sensing" protective signals from the microbiome, defining a potentially critical gene-environment etiology for IBD.

Foreign body response to subcutaneous implants in diabetic rats

Implantation of synthetic matrices and biomedical devices in diabetic individuals has become a common procedure to repair and/or replace biological tissues. However, an adverse foreign body reaction that invariably occurs adjacent to implant devices impairing their function is poorly characterized in the diabetic environment. We investigated the influence of this condition on the abnormal tissue healing response in implants placed subcutaneously in normoglycemic and streptozotocin-induced diabetes in rats. In polyether-polyurethane sponge discs removed 10 days after implantation, the components of the fibrovascular tissue (angiogenesis, inflammation, fibrogenesis, and apoptosis) were assessed. Intra-implant levels of hemoglobin and vascular endothelial growth factor were not different after diabetes when compared with normoglycemic counterparts. However, there were a lower number of vessels in the fibrovascular tissue from diabetic rats when compared with vessel numbers in implants from non-diabetic animals. Overall, the inflammatory parameters (neutrophil accumulation - myeloperoxidase activity, tumor necrosis factor alpha, and monocyte chemotactic protein-1 levels and mast cell counting) increased in subcutaneous implants after diabetes induction. However, macrophage activation (N-acetyl-β-D-glucosaminidase activity) was lower in implants from diabetic rats when compared with those from normoglycemic animals. All fibrogenic markers (transforming growth factor beta 1 levels, collagen deposition, fibrous capsule thickness, and foreign body giant cells) decreased after diabetes, whereas apoptosis (TUNEL) increased. Our results showing that hyperglycemia down regulates the main features of the foreign body reaction induced by subcutaneous implants in rats may be relevant in understanding biomaterial integration and performance in diabetes.

Diabetes alters inflammation, angiogenesis, and fibrogenesis in intraperitoneal implants in rats

The increased prevalence of diabetes worldwide is associated with increasing numbers of diabetic individuals receiving synthetic matrices and biomedical implants to repair and/or replace biological tissues. This therapeutic procedure invariably leads to adverse tissue healing (foreign body reaction), thus impairing the biomedical device function of subcutaneous implants. However, the influence of diabetes on abnormal tissue healing in intraperitoneal implants is unclear. We investigated key components of foreign body reactions in diabetic rats. Polyether-polyurethane sponge discs were placed intraperitoneally in rats previously injected with streptozotocin for induction of diabetes and in non-diabetic rats. Implants removed 10 days after implantation were assessed by determining the components of the fibrovascular tissue (angiogenesis, inflammation, and fibrogenesis). In implants from diabetic rats, fibrous capsule thickness and fibrovascular tissue infiltration (hematoxylin & eosin and picrosirius staining) were reduced in comparison with implants from non-diabetic rats. Hemoglobin (Hb) content (vascular index) and VEGF levels (pro-angiogenic cytokine) were increased after diabetes. However, the number of vessels (H&E and CD31-immunostaining) in the fibrovascular tissue from diabetic rats was decreased when compared with vessel numbers in implants from non-diabetic animals. Overall, all inflammatory parameters (macrophage accumulation-NAG activity; TNF-α and MCP-1 levels) increased in intraperitoneal implants after diabetes induction. The pro-fibrogenic cytokine (TGFβ-1) increased after diabetes, but collagen deposition remained unaltered in the implants from diabetic rats. These important diabetes-related changes (increased levels of pro-inflammatory and angiogenic and fibrogenic cytokines) in peritoneal implant healing provide an insight into the mechanisms of the foreign body response in the diabetic environment in rats.

A comparative study of apoptosis in reticular and erosive oral lichen planus

The oral lichen planus (OLP) is a chronic inflammatory disease, probably autoimmune, with different clinical forms. The most common types are the reticular and the erosive ones. Apoptosis participates in the destruction of basal keratinocytes, but its role in the perpetuation of the subepithelial lymphocytic infiltrates was not yet investigated. To evaluate the involvement of apoptosis in the epithelium and in subepithelial lymphocytic infiltrates, 15 samples of reticular and erosive OLP and 10 samples of healthy oral mucosa were collected and processed histologically. Apoptosis was quantified in the epithelium and in inflammatory cell infiltrates. TUNEL reaction was used to measure apoptosis in the infiltrates. Erosive OLP showed more intense epithelial apoptosis than reticular OLP and controls. In contrast, apoptosis in the inflammatory cell infiltrates was more frequent in reticular than in erosive OLP. Lymphocytes were the predominant cells within the inflammatory cell infiltrates and were more frequent in erosive OLP than in reticular type. These results suggest that different apoptotic levels are involved in the erosive/reticular switch in OLP, determining different clinical presentations. In conclusion, decreased apoptosis in inflammatory infiltrates may contribute to the persistence of T lymphocytes, worsening the attack to the epithelium in erosive OLP.

Caspase-3/caspase-8, bax and bcl2 in pulps of human primary teeth with physiological root resorption

OBJECTIVE. Physiological root resorption is a programmed event that takes place in primary teeth leading to elimination of all root structures. The mechanism behind pulp elimination indicates apoptosis, but its pathway has not been well characterised yet. To better understand this event, we evaluated the gene expression of bax, bcl-2, caspase-3 and caspase-8 through real-time polymerase chain reaction (PCR) and immunohistochemistry expression of Caspase-8 and Bax in pulps. METHODS. Samples were split into two groups: pulps from primary teeth with physiological root resorption (n = 40) and control (n =40), pulps from permanent teeth. Samples of each group were split into PCR (n = 20) and immunohistochemistry (n = 20). RESULTS.  Pulps from primary teeth showed a higher caspase-3 mRNA level than pulps from permanent teeth. The expression of bax gene was more intense than caspase-8 but both did not show difference between groups. The bcl-2 mRNA level was incipient and similar between groups. Histopath slides did not show any evidence of inflammatory infiltration, which implies that extrinsic via is not likely to be involved. Immunohistochemistry reaction to Bax and Caspase-8 supported PCR results. CONCLUSIONS. Pulp apoptosis is likely to occur via caspase-3 activation through the mitochondrial pathway.

Vero cells infected with the Lederle strain of canine distemper virus have increased Fas receptor signaling expression at 15 h post-infection

We evaluated the expression of the Fas receptor gene in Vero cells infected with the Lederle vaccine strain of canine distemper virus using RT-PCR. Vero cells were plated, and after being grown for 24 h in MEM with 5% FBS, 80-90% confluent monolayer cultures were infected with the virus. The cells were harvested at 3, 6, 9, and 15 h post-infection. Uninfected Vero cells were used as a control. Total RNA was isolated from Vero cells using 1 mL Trizol(®) LS, and RT was performed using 2 μg total RNA. Primer pairs for RT-PCR amplification for the canine distemper virus nucleocapsid gene, the S26 reference gene, and the Vero rFas gene were used to analyze expression in Vero cells. RT-PCR results revealed virus activity at 3, 6, 9, and 15 h in the virus-infected Vero cells. The S26 housekeeping gene was amplified in virus infected and control samples. However, expression of the cell death receptor Fas was detected in Vero cells only at 15 h post-infection. We suggest that the Lederle vaccine induces apoptosis by Fas receptor signaling, possibly through caspase-8 signaling rather than through mitochondrial signaling in the infected cells.

MyD88 and STING signaling pathways are required for IRF3-mediated IFN-β induction in response to Brucella abortus infection

Type I interferons (IFNs) are cytokines that orchestrate diverse immune responses to viral and bacterial infections. Although typically considered to be most important molecules in response to viruses, type I IFNs are also induced by most, if not all, bacterial pathogens. In this study, we addressed the role of type I IFN signaling during Brucella abortus infection, a facultative intracellular bacterial pathogen that causes abortion in domestic animals and undulant fever in humans. Herein, we have shown that B. abortus induced IFN-β in macrophages and splenocytes. Further, IFN-β induction by Brucella was mediated by IRF3 signaling pathway and activates IFN-stimulated genes via STAT1 phosphorylation. In addition, IFN-β expression induced by Brucella is independent of TLRs and TRIF signaling but MyD88-dependent, a pathway not yet described for Gram-negative bacteria. Furthermore, we have identified Brucella DNA as the major bacterial component to induce IFN-β and our study revealed that this molecule operates through a mechanism dependent on RNA polymerase III to be sensed probably by an unknown receptor via the adaptor molecule STING. Finally, we have demonstrated that IFN-αβR KO mice are more resistant to infection suggesting that type I IFN signaling is detrimental to host control of Brucella. This resistance phenotype is accompanied by increased IFN-γ and NO production by IFN-αβR KO spleen cells and reduced apoptosis.

Apoptose na maturação placentária de vacas em diferentes estágios de gestação: evidenciação imuno-histoquímica e bioquímica

Apoptose tem um papel importante na manutenção da homeostase placentária, e o desequilíbrio desse processo pode comprometer a gestação. O objetivo do presente estudo foi avaliar a ocorrencia de apoptose em amostras de placenta de vacas em diferentes fases de gestação. Amostras de placentomos de 15 vacas saudáveis com 4 (n=5), 6 (n=5) e 9 (n=5) meses de gestação foram colhidas e processadas rotineiramente para a histologia, imuno-histoquímica e isolamento de DNA. As lâminas obtidas foram coradas em HE, ou submetidas à análise imuno-histoquímica das proteínas pró-apoptóticas caspase-3 e Bax, e da proteína anti-apoptótica Bcl-2. O DNA isolado foi submetido à eletroforese em gel de agarose para detecção da fragmentação internucleossômica do genoma. Os resultados de histomorfometria revelaram que as células apoptóticas aumentaram progressivamente com o avanço da gestação. Confirmou-se a apoptose pela fragmentação característica do DNA genômico, visualizada pelo clássico "padrão em escada" na eletroforese em gel de agarose. Adcionalmente, a imunoexpressão de caspase-3, Bax e Bcl-2 foram observadas em todas as amostras. Entretanto, a proteína caspase-3 apresentou marcação mais intensa em todos os tempos gestacionais, quando comparada com a marcação das proteínas Bcl-2 e Bax. Esses resultados confirmam e reforçam a importância da apoptose na maturação placentária. Além disto, indica que caspase-3, Bax e Bcl-2 estão envolvidas nos mecanismos de ativação da apoptose pela via intrínseca mitocondrial ao longo da gestação, contribuindo para o equilíbrio fisiológico da celularidade e renovação celular na placenta bovina.

Canine distemper virus induces apoptosis in cervical tumor derived cell lines

Apoptosis can be induced or inhibited by viral proteins, it can form part of the host defense against virus infection, or it can be a mechanism for viral spread to neighboring cells. Canine distemper virus (CDV) induces apoptotic cells in lymphoid tissues and in the cerebellum of dogs naturally infected. CDV also produces a cytopathologic effect, leading to apoptosis in Vero cells in tissue culture. We tested canine distemper virus, a member of the Paramyxoviridae family, for the ability to trigger apoptosis in HeLa cells, derived from cervical cancer cells resistant to apoptosis. To study the effect of CDV infection in HeLa cells, we examined apoptotic markers 24 h post infection (pi), by flow cytometry assay for DNA fragmentation, real-time PCR assay for caspase-3 and caspase-8 mRNA expression, and by caspase-3 and -8 immunocytochemistry. Flow cytometry showed that DNA fragmentation was induced in HeLa cells infected by CDV, and immunocytochemistry revealed a significant increase in the levels of the cleaved active form of caspase-3 protein, but did not show any difference in expression of caspase-8, indicating an intrinsic apoptotic pathway. Confirming this observation, expression of caspase-3 mRNA was higher in CDV infected HeLa cells than control cells; however, there was no statistically significant change in caspase-8 mRNA expression profile. Our data suggest that canine distemper virus induced apoptosis in HeLa cells, triggering apoptosis by the intrinsic pathway, with no participation of the initiator caspase -8 from the extrinsic pathway. In conclusion, the cellular stress caused by CDV infection of HeLa cells, leading to apoptosis, can be used as a tool in future research for cervical cancer treatment and control.

Alterations in the dynamics of inflammation, proliferation and apoptosis in subcutaneous implants of lupus-prone mice

Wound repair is a complex process that involves inflammation, proliferation, extracellular matrix deposition/remodeling and apoptosis. Autoimmune diseases profoundly affect the healing process. We have used histological parameters to characterize the recruitment of mast cells and the proliferative activity and apoptosis in the fibrovascular tissue induced by subcutaneous polyether-polyurethane sponge implants in lupus-prone New Zealand White (NZW) and in control Balb/c mouse strains at days 10 and 21 post implantation. Fibrovascular tissue infiltration (hematoxylin and eosin staining), mast cell number (Dominici staining) and cellular proliferation (AgNOR staining) peaked early (day 10) but collagen deposition (picrosirius red staining) and apoptosis remained high in implants of NZW mice during the experimental period. In contrast, implants of Balb/c animals showed a progressive increase in mast cell recruitment and cellular proliferation but apoptosis fell from day 10 to 21 post-implantation. This divergent response early mast cells recruitment, excessive collagen deposition and disturbed removal of apoptotic cells from the site of injury in NZW mice implies that the genotype trait of NZW mice is a determining factor in abnormal healing response.

Canine distemper virus detection in asymptomatic and non vaccinated dogs

A quantitative real time polymerase chain reaction (PCR) revealed canine distemper virus presence in peripheral blood samples from asymptomatic and non vaccinated dogs. Samples from eleven domestic dogs with no signs of canine distemper and not vaccinated at the month of collection were used. Canine distemper virus vaccine samples in VERO cells were used as positive controls. RNA was isolated with Trizol®, and treated with a TURBO DNA-free kit. Primers were designed for canine distemper virus nucleocapsid protein coding region fragment amplification (84 bp). Canine b-actin (93 bp) was utilized as the endogenous control for normalization. Quantitative results of real time PCR generated by ABI Prism 7000 SDS Software showed that 54.5% of dogs with asymptomatic canine distemper were positive for canine distemper virus. Dissociation curves confirmed the specificity of the real time PCR fragments. This technique could detect even a few copies of viral RNA and identificate subclinically infected dogs providing accurate diagnosis of this disease at an early stage.

Caspase-3/-8/-9, Bax and Bcl-2 expression in the cerebellum, lymph nodes and leukocytes of dogs naturally infected with canine distemper virus

Canine distemper is an immunosuppressive disease caused by the canine distemper virus (CDV). Pathogenesis mainly involves the central nervous system and immunosuppression. Dogs naturally infected with CDV develop apoptotic cells in lymphoid tissues and the cerebellum, but this apoptotic mechanism is not well characterized. To better understand this process, we evaluated the expression of Bax, Bcl-2, and caspase-3, -8 and -9, by evaluating mRNA levels in the peripheral blood, lymph nodes and cerebellum of CDV-infected (CDV+) and uninfected (CDV-) dogs by real-time polymerase chain reaction (PCR). Blood samples from 12 CDV+ and 8 CDV- dogs, diagnosed by reverse transcription-PCR, were subjected to hematological analysis and apoptotic gene expression was evaluated using real-time-PCR. Tissues from the cerebellum and lymph nodes of four CDV+ and three CDV-dogs were also subjected to real time-PCR. No significant differences were found between CDV+ and CDV- dogs in the hemotological results or in the expression of caspase-3, -8, -9, Bax, and Bcl-2 in the peripheral blood. However, expression of Bax, caspase-3, -8 and -9 was significantly higher in the cerebellum of CDV+ compared to CDV- dogs. Expression of caspase-3 and -8 was significantly higher in the lymph nodes of CDV+ compared to CDV- dogs. We concluded that infection with CDV induces apoptosis in the cerebellum and lymph nodes in different ways. Lymph node apoptosis apparently occurs via caspase-3 activation, through the caspase-8 pathway, and cerebellum apoptosis apparently occurs via caspase-3 activation, through the caspase-8 and mitochondrial pathways.

An outbreak of malignant catarrhal fever in Murrah buffaloes in Minas Gerais, Brazil

An outbreak of Malignant Catarrhal Fever (MCF) resulted in death of five female buffaloes and one domestic cow from the same farm. Four buffaloes died 10-15 days after the appearance of clinical signs, while the fifth was euthanized in extremis, after similar clinical signs. Histopathological lesions included multifocal histiolymphocytic epicarditis, myocarditis and lymphocytic interstitial pneumonia, which are commonly seen in cases of MCF in buffaloes. Furthermore, lymphocytic vasculitis centered in the adventitia, with occasional fibrinoid necrosis in the muscular layer, was found in the kidneys, liver, spleen, lymph nodes and brain. Nucleotide sequencing of DNA fragments from the central nervous system amplified by PCR revealed 98% similarity with known OHV-2 sequences from Genbank. Additionally, PCR analysis also revealed the presence of OHV-2 DNA in the peripheral mononuclear blood cells of two clinically healthy buffaloes. The diagnosis of MCFwas based on epidemiological, clinical, gross and histopathological findings and on the results of a semi-nested PCR followed by nucleotide sequencing.

[Apoptosis, proliferation and spleen histomorphometry of adult female rats with thyroid and ovarian hypofunction]

Apoptosis, proliferation and histomorphometry of spleen were investigated in ovariectomized and non-ovariectomized adult Wistar rats maintained in hypothyroidism induced by daily administration of propylthiouracil (PTU) during 120 days. Two groups ovariectomized euthyroid and non-ovariectomized euthyroid were used as controls. Plasma was collected for free T4 dosage and the spleen for histomorphometry analysis, apoptosis index and the immunohistochemistry expression of caspase 3 and CDC47. Values of free T4 were lower in rats treated with PTU (p<0.05). In the hypothyroid groups there was some decrease in the spleen weight as well as the number and size of lymphoid follicles and there was some increase in the apoptotic index and the caspase 3 expression (p<0.05). However, the increase in the apoptosis index and the expression of caspase 3 in ovariectomized hypothyroid rats spleen was less accentuated than non-ovariectomized hypothyroid ones (p<0.05). The ovariectomized euthyroid group presented white pulp hyperplasia in comparison to the non-ovariectomized euthyroid group. There was no difference in the CDC47 expression between groups. It was concluded that the thyroid and ovarian hypofunction have distinct effects on the spleen and that in the hypothyroidism-hypogonadism association, the increase in the apoptosis index and in the expression of splenic caspase 3 is not as much as in isolated hypothyroidism.

Role of apoptosis in erosive and reticular oral lichen planus exhibiting variable epithelial thickness

Oral lichen planus (OLP) is a chronic inflammatory disease with different clinical types. Reticular and erosive forms are the most common. Although the cause of OLP remains speculative, many findings suggest auto-immune involvement, mediated by T lymphocytes against the basal keratinocytes. Inflammation, mechanical trauma or toxic agents can affect the epithelial homeostasia. Increased apoptosis may cause a decrease in epithelial thickness reflecting in the activity of the lesion. The objective of this study was to evaluate the occurrence of apoptosis and epithelial thickness in reticular and erosive forms of OLP. 15 samples of OLP each type (reticular and erosive) plus 10 of healthy mucosa were collected and processed. After morphometry, the apoptotic index and epitelial thickness were obtained. TUNEL and M30 CytoDEATH immunohistochemical assay were used to validate the morphologic criteria used. Apoptosis in the erosive OLP was significantly more intense than in the reticular type and both forms of OLP presented more apoptosis than the healthy oral mucosa. Healthy oral mucosa was thicker than both OLP forms and thicker in OLP reticular form than in the erosive one. The clinical differences between reticular and erosive forms of OLP are related to variations in epithelial thickness and in intensity of apoptosis.

Epidemiologia e sinais clínicos da conidiobolomicose em ovinos no Estado do Piauí

Foi realizado um estudo de ocorrência da conidiobolomicose ovina em 25 rebanhos no Estado do Piauí, de janeiro de 2002 a dezembro de 2004. A enfermidade acometeu apenas ovinos e ocorreu principalmente em abril-julho. A incidência média anual foi de 2,80% e a incidência semestral foi significativamente mais alta (P <0,05) no primeiro semestre (2,10%), durante a época chuvosa, do que no segundo semestre (0,69%), durante a seca. A incidência entre rebanhos variou de 0,1-14,3% e a letalidade foi de 100%. Ao exame clínico, os animais apresentavam apatia, emagrecimento progressivo, secreção nasal serosa, mucosa e/ou hemorrágica, dificuldade respiratória, respiração ruidosa, febre e na maioria dos casos assimetria crânio-facial e exoftalmia. Alguns ovinos permaneciam com a cabeça baixa ou a pressionavam contra objetos. O curso clínico foi de 1-5 semanas. As lesões macroscópicas, microscópicas e ultrastructurais e a identificação do agente são descritas separadamente. Este é o primeiro registro de conidiobolomicose em ovinos no Brasil, enfermidade endêmica no Estado do Piauí, associada à alta pluviosidade (1000-1600mm anuais) e alta temperatura (19-36ºC).

Cellular proliferation, differentiation and apoptosis in polyether-polyurethane sponge implant model in mice

The integration of implanted material to host organism requires spatial and temporal organization of several cellular processes, such as proliferation, differentiation and apoptosis. Despite the clinical relevance of these processes, there is little information regarding the sequence of such events in synthetic matrices. Here, we present a combination of techniques used to characterize the fibrovascular response in subcutaneous polyether-polyurethane sponge implants in mice at days 4, 7, 10 and 14 postimplantation. The AgNOR technique was modified and used as a surrogate marker for proliferating and activated cells invading the implant. The number of AgNOR-stained cells increased progressively from day 4 (606+/-76) to day 14 (2146+/-71) postimplantation. The number of TUNEL-positive (apoptotic index) cells also increased progressively from day 4 (459+/-40) to day 14 (1157+/-119) postimplantation. However, the ratio of TUNEL-labeled/proliferating cells had its highest peak in the early phase of the process remaining stable until day 14. Using Picrosirius staining it was shown that thin collagen increased from day 4, peaking at day 10 and falling markedly at day 14, whereas dense collagen increased progressively during the whole period. These experiments hold potential to investigate not only distinct phases of tissue repair induced by synthetic matrices but also to study underlying mechanisms involved.

Efeito da mitomicina C em cultura de estroma de pólipos nasais eosinofílicos: indução de apoptose em eosinófilos

A polipose nasossinusal eosinofílica é uma afecção comum a várias doenças, determina acometimento extenso dos seios paranasais e possui grande tendência à recidiva após tratamento. Os eosinófilos exercem papel essencial na patogênese, relacionada a baixo índice de apoptose e a longa permanência destas células ativas nos tecidos. OBJETIVO: Este estudo teve por objetivo avaliar o efeito da mitomicina C na indução de apoptose em eosinófilos presentes no estroma de pólipos nasais eosinofílicos. FORMA DE ESTUDO: Caso controle. MATERIAL E MÉTODO: O estudo foi auto-pareado, com 9 amostras cultivadas em meio RPMI 1640 e avaliadas em zero, 12 e 24 horas. O grupo estudo recebeu mitomicina C numa concentração de 400µg/ml durante 5 minutos. Em cada tempo as duas culturas, controle e estudo, foram submetidas a estudo histopatológico para determinação do índice apoptótico. Utilizou-se a coloração hematoxilina-eosina com aumento microscópico de 1000x. RESULTADO: Pela análise de 674 campos digitalizados observou-se que as culturas tratadas com mitomicina C apresentaram índice apoptótico em 12 horas significativamente maior em relação ao grupo controle (p< 0,001). CONCLUSÃO: Concluiu-se que a mitomicina C é eficaz na indução de apoptose em eosinófilos presentes em estroma de pólipos nasais eosinofílicos.

Sponge-induced angiogenesis and inflammation in PAF receptor-deficient mice (PAFR-KO)

1. To determine biological functions of platelet-activating factor (PAF) in chronic inflammation, we have investigated the kinetics of angiogenesis, inflammatory cells recruitment and cytokine production in sponge-induced granuloma in wild type and PAF receptor-deficient mice (PAFR-KO). 2. Angiogenesis as determined by morphometric analysis and hemoglobin content was significantly higher in the implants of PAFR-KO mice at all time points. Treatment with PAF receptor antagonist UK74505 (30 mg kg(-1)) also increased angiogenesis in sponge implants. 3. Neutrophils and macrophages accumulation, as determined by myeloperoxidase and N-acetylglucosaminidase activities in the supernatant of implanted sponges were markedly decreased in PAFR-KO mice. Surprisingly, the levels of the proinflammatory chemokines, keratinocyte-derived chemokine and chemokine monocyte chemoattractant protein 1 were higher in the implants of the transgenic animals. 4. We have shown that angiogenesis was stimulated in PAFR-KO mice whereas inflammation was decreased, indicating that PAF is an endogenous regulator of new blood vessels formation in the inflammatory microenvironment induced by the sponge implant.

Apoptosis in the cerebellum of dogs with distemper

Canine distemper virus (CDV) may induce multifocal demyelination in the central nervous system of infected dogs. The pathogenesis of this process is not clear. The present work identifies the presence of apoptotic cells in white and grey matter of dogs'cerebellum, naturally infected with CDV. Fifteen dogs with clinical signs of canine distemper that tested positive for CDV nucleoprotein were used. Brain specimens were processed and embedded in paraffin. Sections 5 microm thick were stained with hematoxylin-eosin and Shorr. Other sections were submitted to TUNEL reaction and to immunohistochemistry for CDV nucleoprotein detection. Acute and chronic demyelinated plaques were observed in the white matter, while apoptosis occurred particularly in the granular layer of grey matter. Apoptosis seems to play an important role in the pathogenesis of canine distemper demyelination.

Apoptosis in canine distemper

Canine distemper is a systemic viral disease characterized by immunosuppression followed by secondary infections. Apoptosis is observed in several immunosuppressive diseases and its occurrence on canine distemper in vivo has not been published. In this study, the occurrence of apoptosis was determined in lymphoid tissues of thirteen naturally infected dogs and nine experimentally inoculated puppies. Healthy dogs were used as negative controls. Samples of lymph nodes, thymus, spleen and brain were collected for histopathological purposes. Sections, 5 microm thick, of retropharingeal lymph nodes were stained by HE, Shorr, Methyl Green-Pyronin and TUNEL reaction. Shorr stained sections were further evaluated by morphometry. Canine distemper virus nucleoprotein was detected by immunohistochemistry. Retropharingeal lymph nodes of naturally and experimentally infected dogs had more apoptotic cells per field than controls. In addition, DNA from thymus of infected dogs were more fragmented than controls. Therefore, apoptosis is increased in lymphoid depletion induced by canine distemper virus and consequently play a role in the immunosuppression seen in this disease.

[Reactivation of Trypanosoma cruzi infection in patients with acquired immunodeficiency syndrome]

A patient with AIDS and asymptomatic Chagas's disease and positive xenodiagnosis was taking ketoconazole in order to suppress parasitemia and prevent reactivation of Chagas's disease. Ketoconazole was unplanned suspended after 6 months, and the patient was admitted with fever, headache, vomiting, tachycardia, postural hypotension, hepatosplenomegaly, and positive xenodiagnosis one month later. Treatment with benzonidazole was begun leading to suppression of parasitemia. The patient had probability a neurotoxoplasmosis associated and progressed to coma and death with sepsis. No parasite was found in autopsy.

Effect of growth hormone and induced IGF-I release on germ cell population and apoptosis in the bovine testis

Bovine growth hormone has been used in dairy cattle to increase milk production,but it also increases the twin parturition rate. This effect is mediated by insulin-like growth factor-I (IGF-I), which prevents follicular atresia by hindering apoptosis of granulosa cells. The action of GH and IGF-I on testicular function remains unclear. The goal of this study, therefore, was to verify the effects of short-term administration of GH and induced IGF-I release on the number of testicular germ cells, testicular morphology, and apoptosis in the bovine testis. Twenty Zebu bulls were split into 2 groups. The bulls in Group 1 (n = 10) were treated with 2 subcutaneous injections of bovine GH (500 mg/bull) 7 d apart. Group 2 bulls (n = 10) received placebos under the same protocol. All of the bulls were slaughtered 14 d after the start of treatment. Fragments of the testis were collected, fixed in Bouin's solution, embedded in paraffin, and the sections stained with hematoxilin and eosin. The paraffin-embedded sections were also used for in situ detection of apoptotic cells. Blood samples were collected at slaughter to measure serum levels of IGF-I, FSH and LH. Neither the number of Stage I seminiferous epithelium germ cells and the morphometric parameters (tubular diameter, seminiferous epithelium height, and volumetric proportions of structural components) nor the blood levels of FSH and LH showed a significant difference between the 2 groups. However, the treated animals showed an increase in serum IGF-I (P<0.01). Apoptotic germ cells were detected in the testis of both groups, showing the same pattern and a stage-specific apoptosis pattern. Most of the labeled cells were spermatocytes. The localization of apoptotic germ cells did not differ between groups. These results suggest that short-term administration of GH does not affect bovine spermatogenesis in adult bulls.

Spinach cytosolic fructose-1,6-bisphosphatase: II. Light effect on its expression

The effect of light on the expression of spinach (Spinacia oleracea) cytosolic fructose-1,6-bisphosphatase (FBPase) was determined by the level of mRNA, protein content, and enzyme activity. It was found that its expression and activity were constant and stable during normal daily conditions as well as under continuous light or dark conditions. However, two different mRNAs were detected; one transcript was expressed all the time, while the other was detected only during prolonged dark periods. Analysis of the expression of the mRNAs at the protein level using an activity gel showed that this "darkness-specific" mRNA encoded a separate, distinct polypeptide. Thus, our data suggest that cytosolic FBPase is encoded by a small multigene family.

Spinach cytosolic fructose-1,6-bisphosphatase: I. Its organ-specific and developmental expression characteristics

Spinach (Spinacia oleracea) cytosolic fructose-1,6-bisphosphatase (FBPase) was purified and the final preparation of protein has a specific activity of about 45 units/mg protein and a single band of molecular mass of 39 kDa. Polyclonal antibody against the protein did not cross-react with chloroplast FBPase, but showed strong cross-reactivity with all plant cytosolic FBPases tested. Studies of the FBPase expression characteristics at early stages of development demonstrated that it was controlled at both the transcriptional and translational levels, and its mRNA was detected even in etiolated cotyledons. This suggests that the expression is not light-inducible. A single transcript was detected in all spinach tissues tested. Western blot analysis revealed two protein bands in the etiolated cotyledons: one was the same size as that present in the mature leaf, and the other slightly smaller. A high enzyme activity was detected in etiolated cotyledons, especially compared to protein levels in Western blots. Expression of the cytosolic FBPase gene during leaf development showed no change in the steady-state level of mRNA, but the protein level and enzyme activity were higher in mature leaves than in young ones, suggesting that the increase in FBPase activity during development is due to an increase in protein synthesis. Young roots showed low enzyme activity, but an unexpectedly high activity was detected in old fiber roots.

[Comparison of methods to test the "in vitro" cytotoxicity of biocompatible materials]

OBJECTIVE

A comparison of the sensitivity of the agar diffusion method with that of extraction using cell-lines RC-IAL (fibroblastic of rabbit kidney) and HeLa (epithelial carcinoma cells from the cervix uteri of the human uterus), in the in vitro evaluation of materials of medical and hospital.

MATERIALS AND METHODS

Fifteen samples chosen at random, from among the already known positives and negatives in our stock, were tested and identified as cotton, form, latex, cellulose and acrylic. Besides the samples mentioned, many SDS (GIbco) concentrations were tested experimentally in RC-IAL and HeLa cell cultures.

RESULTS

Of the 50 samples tested, 44(88%) were positive by both methods. However, when the SDS were compared by using the two methods, positive results were noted in the concentrations of from 0.5 to 0.05 microgram/ml in the agar diffusion ans extraction methods. A cytotoxic effect was only noted in the concentrations of up to 0.25 microgram/ml.

CONCLUSION

When the SDS was used, differences favorable to the agar diffusion method were observed in the two cell lines, in two concentrations; that is, the sensitivity of this method was quantitatively greater on inspection than that of the extraction method, as well as being the simpler method to use.

Physical association of KAB1 with plant K+ channel alpha subunits

K+ channel proteins contain four alpha subunits that align along a central axis perpendicular to membranes and form an ion-conducting pore. Recent work with K+ channels native to animal membranes has shown that at least some members of this protein family also have four beta subunits. These structural components of the holoenzyme each form tight associations with the cytoplasmic portion of an alpha subunit. We have cloned an Arabidopsis cDNA (KAB1) that encodes a polypeptide sharing 49% amino acid identity with animal K+ channel beta subunits. In this study, we provide experimental evidence that the KAB1 polypeptide forms a tight physical association with the Arabidopsis K+ channel alpha subunit, KAT1. An affinity-purified KAB1 fusion protein was immobilized to a support resin and shown to sequester selectively the KAT1 polypeptide. In addition, polyclonal antibodies raised against KAB1 were shown to immunoprecipitate the KAT1 polypeptide as a KAT1-KAB1 protein complex. Immunoblot analysis demonstrated that KAB1 is expressed in Arabidopsis seedings and is present in both membrane and soluble protein fractions. The presence of KAB1 (a soluble polypeptide) in both soluble and membrane protein fractions suggests that a portion of the total amount of native KAB1 is associated with an integral membrane protein, such as KAT1. The presence of KAB1 in crude protein fractions prepared from different Arabidopsis plant organs was evaluated. High levels of KAB1 protein were present in flowers, roots, and leaves. Immunoblot analysis of protein extracts prepared from broad bean leaves indicated that the KAB1 expression level was 80-fold greater in guard cells than in mesophyll cells. Previous studies of the in situ transcription pattern of KAT1 in Arabidopsis indicated that this alpha subunit is abundantly present in leaves and, within the leaf, exclusively present in guard cells. Thus, KAB1 was determined to be expressed in plant organs (leaves) and cell types (guard cells) that are sites of KAT1 expression in the plant. The in situ expression pattern of KAB1 suggests that it may associate with more than one type of K+ channel alpha subunit. Sequence analysis indicates that KAB1 may function in plant K+ channels as an oxidoreductase. It is postulated that beta subunits native to animal K+ channels act as regulatory subunits through pyridine nucleotide-linked reduction of alpha polypeptides. Although the KAB1 primary structure is substantially different from that of animal beta subunits, amino acid motifs critical for this catalytic activity are retained in the plant beta subunit.

Evidence that plant K+ channel proteins have two different types of subunits

Plant K+ channel proteins have been previously characterized as tetramers of membrane-spanning alpha subunit polypeptides. Recent studies have identified a 39-kD, hydrophilic polypeptide that is a structural component of purified animal K+ channel proteins. We have cloned and sequenced an Arabidopsis thaliana cDNA encoding a 38.4-kD polypeptide that has a sequence homologous to the animal K+ channel beta subunit. Southern and northern analyses indicate the presence of a gene encoding this cDNA in the Arabidopsis genome and that its transcription product is present in Arabidopsis cells. To our knowledge, this is the first report to document the presence of K+ channel beta subunits in plants.

Apoptosis as a cause of death in chicken embryos inoculated with Newcastle disease virus

Eleven-day-old chicken embryos were inoculated by the allantoic route with the GB strain of Newcastle disease virus (NDV). At 0, 24, 36 and 42 h post-inoculation (p.i.), the brain and heart tissues were harvested for DNA extraction, and the thymus and the brain were fixed and processed for light and electron microscopy. At 42 h p.i., most of the embryos had died; however, no histopathological changes could be seen in the embryos at any stage of infection. DNA extracted from the brain cells started showing fragmentation at 24 h p.i., and from the heart muscle cells at 36 h p.i. Electron microscopy of the brain and thymus showed condensation of the nuclear chromatin, apoptotic bodies, various forms of crescent formation and some evidence of necrosis. Fragmentation of cellular DNA, crescent formation and apoptotic bodies are the typical signs of cells undergoing apoptosis. We suggest that apoptosis of the heart and brain is probably a cause of death of chicken embryos in acute Newcastle disease infection.

Apoptosis in chicken embryos induced by the infectious bursal disease virus

Fifteen-day-old fertile eggs (specific pathogen-free) were inoculated with the infectious bursal disease virus (IBDV) by the allantoic route and were opened and examined 2, 4 or 6 days later. The bursas of Fabricius (BFs) were collected and processed for DNA extraction, flow cytometry, and light and electron microscopy. Cellular DNA was subjected to electrophoresis on 1.5% agarose gel and stained with ethidium bromide. Intense internucleosomal DNA fragmentation was detected in IBDV-infected bursas. Cytograms from cell suspensions derived from infected BFs displayed an increased population of cells with either high density and small size (apoptotic cells) or small size and high uptake of ethidium bromide (necrotic cells). Light and electron microscopical examination of the IBDV-infected BFs revealed death of lymphoid cells without surrounding inflammatory reaction, but with condensation of nuclear chromatin, crescent formation, and nuclear and cellular fragmentation. These data indicated that infection of chicken embryos with IBDV induced apoptosis in bursal lymphoid cells.

Newcastle disease virus-induced apoptosis in chicken peripheral blood lymphocytes

Chicken peripheral blood lymphocytes (PBL) were infected with the GB strain of Newcastle disease virus (NDV). At 0, 1.5 and 3 h postinfection, PBL were stained with acridine orange-ethidium bromide and examined for apoptotic and necrotic indices under a UV microscope. At the end of 3 h, the cells were pelleted and were either fixed for electron microscopy or used for DNA extraction. Infected cells showed a significant amount of apoptosis and necrosis when compared with controls. Electron microscopy of the infected cells also showed characteristics of apoptosis, i.e. apoptotic bodies, margination of chromatin with crescent formation and fusion of cells. DNA extracted from virus-infected cells showed extensive fragmentation. Based on these findings it is concluded that NDV, in addition to causing necrosis in chicken lymphocytes, can induce apoptosis.

Apoptosis induced by infectious bursal disease virus

Chicken peripheral blood lymphocytes (PBLs) show morphological and biochemical features of apoptosis (programmed cell death) when infected in vitro with infectious bursal disease virus (IBDV). DNA extracted from IBDV-infected lymphocytes displayed an intense laddering pattern when visualized after agarose gel electrophoresis. IBDV-infected PBLs had significantly higher apoptotic and necrotic indices measured by acridine orange-ethidium bromide staining than did control lymphocytes. Electron micrographs of the IBDV-infected PBLs revealed features typical of apoptosis such as peripheral condensation of chromatin, blebbing of the plasma membrane and fragmentation of the nucleus and of the cell leading to the formation of apoptotic bodies. These findings indicate that IBDV, in addition to causing necrosis, can also induce apoptosis in avian lymphocytes in vitro.

The transit peptide of a chloroplast thylakoid membrane protein is functionally equivalent to a stromal-targeting sequence

The role of transit peptides in intraorganellar targeting has been studied for a chlorophyll a/b binding (CAB) polypeptide of photosystem II (PSII) and the small subunit of ribulose-1,5-bisphosphate carboxylase (RBCS) from Pisum sativum (pea). These studies have involved in vitro import of fusion proteins into isolated pea chloroplasts. Fusion of the CAB transit peptide to RBCS mediates import to the stroma, as evidenced by assembly of RBCS with chloroplast-synthesized large subunit (RBCL) to form holoenzyme. Similarly, fusion of the RBCS transit peptide to the mature CAB polypeptide mediates import and results in integration of the processed CAB protein into the thylakoid membrane. Correct integration was indicated by association with PSII and assembly with chlorophyll to form the light-harvesting chlorophyll a/b protein complex (LHCII). We interpret these results as evidence that the CAB transit peptide is functionally equivalent to a stromal-targeting sequence and that intraorganellar sorting of the CAB protein must be determined by sequences residing within the mature protein. Our results and those of others suggest that import and integration of CAB polypeptides into the thylakoid proceeds via the stroma.

Purification and characterization of mitochondrial citrate synthase

Mitochondrial citrate synthase was purified from leaves of Pisum sativum L. cv Progress 9. A three step purification was employed using ATP-Sepharose affinity chromatography which resulted in a 600-fold enrichment. Enzyme activity was assayed spectrophotometrically during greening of etiolated leaves under constant white light illumination. An increase (1.4 fold) in citrate synthase activity was observed in response to light. Immunoblot analysis of the same samples indicated a constant steady state level of citrate synthase on a per milligram protein basis. These investigations provide supportive evidence for the ability of this trichloroacetic acid cycle enzyme to be active in photosynthesizing tissue.

Leaf water potential, stomatal resistance, and photosynthetic response to water stress in peach seedlings

Individual groups of peach (Prunus persica [L.] Batsch) seedlings stressed to -17, -26 and -36 bars recovered to control levels within 1, 3, and 4 days, respectively. Stomatal resistance was significantly correlated with both leaf water potential and net photosynthesis. In seedlings stressed to -52 bars, leaf water potential and stomatal resistance recovered sooner than net photosynthesis, despite recovery of 0(2) evolution at a rate similar to leaf water potential. Therefore, some nonstomatal factor other than reduction in photochemical activity must be responsible for the lag in recovery of CO(2) assimilation following irrigation.

Freeze-fracture architecture and polypeptide composition of thylakoid membranes from euploid Ricinus cells

The freeze-fracture architecture and polypeptide composition of thylakoid membranes of euploid cells of Ricinus communis L. were examined. Electron microscopic examination of the chloroplasts of 1N 2N and 4N cells revealed little variation in the size of chloroplasts, lamellar structure and internal organization of plastids, despite increases in plastid numbers per cell observed to accompany the increase in nuclear ploidy. Thylakoid membranes from euploid cells were also similar in their freeze-fracture morphology. Two basic types of intramembranous particles were observed on the fracture faces of thylakoid membranes of euploid cells. The endoplasmic fracture (EF) face of experimentally unstacked thylakoid membranes of 1N, 2N and 4N cells contain 2 size categories of particles (115-121 A and 164-166 A), whereas the protoplasmic fracture (PF) face of these membranes contain a single size category of particles (85-88 A). The distribution and size of the EF- and PF-face particles were found to be similar among membranes from cells of the 3 ploidy levels. Analysis of the polypeptide composition of thylakoid membranes from 1N, 2N and 4N cells revealed no difference in the relative proportion of the constituent polypeptides of these membranes. The possible factors involved in the regulation of the development of thylakoid structure and composition in the presence of altered nuclear genome size are discussed.

Euploidy in Ricinus: EUPLOIDY EFFECTS ON PHOTOSYNTHETIC ACTIVITY AND CONTENT OF CHLOROPHYLL-PROTEINS

The effects of nuclear genome duplication on the chlorophyll-protein content and photochemical activity of chloroplasts, and photosynthetic rates in leaf tissue, have been evaluated in haploid, diploid, and tetraploid individuals of the castor bean, Ricinus communis L. Analysis of this euploid series revealed that both photosystem II (2,6-dichlorophenolindophenol reduction) and photosystem I oxygen uptake (N,N,N',N'-tetramethyl-p-phenylenediamine to methyl viologen) decrease in plastids isolated from cells with increasingly larger nuclear complement sizes. Photosynthetic O(2)-evolution and (14)CO(2)-fixation rates in leaf tissue from haploid, diploid, and tetraploid individuals were also found to decrease with the increase in size of the nuclear genome. Six chlorophyll-protein complexes, in addition to a zone of detergent complexed free pigment, were resolved from sodium dodecyl sulfate-solubilized thylakoid membranes from cells of all three ploidy levels. In addition to the P700-chlorophyll a-protein complex and the light-harvesting chlorophyll a/b-protein complex, four minor complexes were revealed, two containing only chlorophyll a and two containing both chlorophyll a and b. The relative distribution of chlorophyll among the resolved chlorophyll-protein complexes and free pigment was found to be similar for all three ploidy levels.

Euploidy in Ricinus. I. Euploidy and gene dosage effects on cellular proteins

Investigations of an euploid series of castor bean, Ricinus communis L., Consisting of haploid, diploid, and tetraploid individuals, was performed to determine the value of such a series in studying the biochemical consequences of genome multiplication. The effects of euploidization of the nuclear genome on the biosynthesis of cellular proteins were examined. Extracts of total soluble proteins from 10-day-old leaves of all three ploidy levels examined by electrophoresis on polyacrylamide gels revealed no difference in the complement of proteins present; however, differences in intensity of several protein bands were detected. Analysis of esterases isozyme activity by isoelectric focusing revealed both increases and decreases in the activity levels of individual isozyme variants in responses to changes in ploidy levels. Results from this analysis are discussed in terms of possible regulatory mechanisms active in the regulation of duplicated genes.

Synthesis of Proteins by Isolated Euglena gracilis Chloroplasts

Intact Euglena gracilis chloroplasts, which had been purified on gradients of silica sol, incorporated [(35)S]methionine or [(3)H]leucine into soluble and membrane-bound products, using light as the only source of energy. The chloroplasts were osmotically shocked, fractionated on discontinuous gradients of sucrose, and the products of protein synthesis of the different fractions characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The soluble fraction resolved into three zones of radioactivity, the major one corresponding to the large subunit or ribulose diphosphate carboxylase. The thylakoid membrane fraction contained nine labeled polypeptides, the two most prominent in the region of 31 and 42 kilodaltons. The envelope fraction contained a major radioactive peak of about 48 kilodaltons and four other minor peaks. The patterns of protein synthesis by isolated Euglena chloroplasts are broadly similar to those observed with chloroplasts of spinach and pea.

Fractionation and Analysis of Polypeptides of Euglena gracilis Chloroplasts

Intact Euglena gracilis chloroplasts, purified on gradients of silica sol, were lysed osmotically and fractionated by centrifugation on discontinuous gradients of sucrose into their soluble, envelope membrane, and thylakoid membrane components. The proteins of the different subchloroplast fractions, as well as those of whole chloroplasts, were analyzed by electrophoresis on sodium dodecyl sulfate polyacrylamide gels. The polypeptide profile of each fraction was distinctive and was in general similar to the profile obtained for analogous fractions of the chloroplasts of higher plants.The envelope membranes were separated into two fractions in the gradients according to their banding densities. Electron micrographs showed that the light envelope fraction consisted mostly of single-membrane vesicles, whereas the heavy envelope fraction consisted of multiple layers of folded membranes. Both envelope fractions were ultrastructurally distinct from the thylakoid membranes.

Isolation of Intact Chloroplasts of Euglena gracilis by Isopycnic Sedimentation in Gradients of Silica

A technique is described for the isolation of structurally intact and partially active chloroplasts from photoheterotrophically grown Euglena gracilis. The separation of intact chloroplasts from stripped chloroplast membranes and other subcellular particles was achieved by sedimentation in continuous, isosmotic density gradients of Ludox AM, a silica sol.The final preparations contained an average of 93% intact chloroplasts and corresponded to approximately 10% of the the chlorophyll of the original cell suspension and 20 to 30% of the chlorophyll layered on the gradients.The chloroplasts obtained were intact by the criteria of ultrastructure, their content of ribulose diphosphate carboxylase, and their activity in a modified Hill reaction assay (U. Heber and K. A. Santarius. 1970. Z. Naturforsch. 25b: 718-727). In addition, the isolated chloroplasts were capable of incorporating amino acids into protein in the light.