Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 26
Filtrar
Mais filtros












Base de dados
Intervalo de ano de publicação
1.
World J Surg Oncol ; 18(1): 86, 2020 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-32366262

RESUMO

INTRODUCTION: The incidence of synchronous RCC and colorectal cancer is heterogeneous ranging from 0.03 to 4.85%. Instead, only one case of huge colon carcinoma and renal angiomyolipoma was reported. The treatment of synchronous kidney and colorectal neoplasm is, preferably, synchronous resection. Currently, laparoscopic approach has shown to be feasible and safe, and it has become the gold standard of synchronous resection due to advantages of minimally invasive surgery. We presented a case synchronous renal neoplasm and colorectal cancer undergone simultaneous totally robotic renal enucleation and rectal resection with primary intracorporeal anastomosis. As our knowledge, this is the first case in literature of simultaneous robotic surgery for renal and colorectal tumor. CASE PRESENTATION: A 53-year-old woman was affected by recto-sigmoid junction cancer and a solid 5 cm left renal mass. We performed a simultaneous robotic low anterior rectal resection and renal enucleation. Total operative time was 260 min with robotic time of 220 min; estimated blood loss was 150 ml; time to flatus was 72 h, and oral diet was administered 4 days after surgery. The patient was discharged on the eighth post-operative day without peri- and post-operative complication. The definitive histological examination showed a neuroendocrine tumor pT2N1 G2, with negative circumferential and distal resection margins. Renal tumor was angiomyolipoma. At 23 months follow-up, the patient is recurrence free. DISCUSSION AND CONCLUSION: As our knowledge, we described the first case in literature of simultaneous robotic anterior rectal resection and partial nephrectomy for treatment of colorectal tumor and renal mass. Robotic rectal resection with intracorporeal anastomosis surgery seems to be feasible and safe even when it is associated with simultaneous partial nephrectomy. Many features of robotic technology could be useful in combined surgery. This strategy is recommended only when patients' medical conditions allow for longer anesthesia exposure. The advantages are to avoid a delay treatment of second tumor, to reduce the time to start the post-operative adjuvant chemotherapy, to avoid a second anesthetic procedure, and to reduce the patient discomfort. However, further studies are needed to evaluate robotic approach as standard surgical strategy for simultaneous treatment of colorectal and renal neoplasm.


Assuntos
Carcinoma de Células Renais/cirurgia , Neoplasias Colorretais/cirurgia , Neoplasias Renais/cirurgia , Neoplasias Primárias Múltiplas/cirurgia , Nefrectomia/métodos , Protectomia/métodos , Procedimentos Cirúrgicos Robóticos/métodos , Anastomose Cirúrgica , Carcinoma de Células Renais/patologia , Neoplasias Colorretais/patologia , Feminino , Humanos , Rim/patologia , Rim/cirurgia , Neoplasias Renais/patologia , Pessoa de Meia-Idade , Neoplasias Primárias Múltiplas/patologia , Duração da Cirurgia , Reto/patologia , Reto/cirurgia , Fatores de Tempo , Resultado do Tratamento
2.
Nat Prod Res ; 32(16): 1926-1950, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28748726

RESUMO

Natural products (NPs) are secondary metabolites produced and used by organisms for defending or adapting purposes. These molecules were naturally selected during thousands of years to improve the specificity and cover a very wide range of functions, depending on the origin, the habitat and the specific activity carried out in the organism of origin. Due to these intrinsic features, NPs have been used as healing agents since thousands of years and still today continue to be the most important source of new potential therapeutic preparations.The purpose of this review is to provide information about the historical evolution of the NPs investigation methods, focusing attention on the relative benefit/problems emerged after the improvement of the scientific investigations about them, especially over the last two centuries. Taken together, the reported information lead to the central role of NPs in the future of drug development for human needs.


Assuntos
Produtos Biológicos/uso terapêutico , Descoberta de Drogas/métodos , Descoberta de Drogas/história , Descoberta de Drogas/tendências , História do Século XX , História do Século XXI , Humanos , Compostos Fitoquímicos
3.
Perfusion ; 30(8): 694-7, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25870370

RESUMO

Heat exchanger leak on cardiopulmonary bypass is very rare, but serious. The exact incidence is not known. It is an emergency associated with the potential risk of blood contamination, air embolism and haemolysis, difficulty with re-warming, acidosis, subsequent septic shock, multi-organ failure and death. We present a prompt, highly co-ordinated algorithm for the successful management of this important rare complication. There is need for further research to look for safety devices that detect leaks and techniques to reduce bacterial load. It is essential that teams practice oxygenator change-out routines and have a well-established change-out protocol.


Assuntos
Ponte Cardiopulmonar/efeitos adversos , Falha de Equipamento , Calefação/instrumentação , Hipotermia/prevenção & controle , Idoso , Feminino , Humanos , Hipotermia/etiologia , Prognóstico
4.
Biochim Biophys Acta ; 1850(4): 759-68, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25597953

RESUMO

BACKGROUND: Experimental studies of antimicrobial peptides interacting with lipid membranes recently attracted growing interest due to their numerous biomedical applications. However, the influence of such peptides on the structural organisation of lipid membranes in connection with the actual cell response still remains an elusive issue. METHODS: X-ray diffraction was employed on detecting the sensitivity of the periodical spacing of dipalmitoyl-phosphatidyl-choline stacked as solid-supported bilayers to the presence of varying amounts of the peptide alamethicin in a wide range of peptide-to-lipid molar ratios. These results were then correlated with the effects of alamethicin on biological membranes in vitro as observed by optical microscopy and microculture tetrazolium assay on the tumour cells HeLa to provide a comprehensive and quantitative analysis of these effects, based on a dose-response relationship. RESULTS: The experiments allowed correlating the periodical spacing and the peptide-to-lipid molar ratio on alamethicin-dipalmitoyl-phosphatidyl-choline samples. Two different trends of periodical spacing vs. peptide-to-lipid molar ratio clearly appeared at low and high hydration levels, showing intriguing non-linear profiles. Unexpected correspondences were observed between the peptide-to-lipid molar ratio range where the changes in dipalmitoyl-phosphatidyl-choline structure occur and the alamethicin doses which alter the viability and the plasma membrane morphology of HeLa. CONCLUSIONS: Alamethicin might induce either mechanical or phase changes on dipalmitoyl-phosphatidyl-choline bilayers. Such easily accessible ordering information was well-calibrated to predict the alamethicin doses necessary to trigger cell death through plasma membrane alterations. GENERAL SIGNIFICANCE: This benchmark combined study may be valuable to predict bioeffects of several antimicrobial peptides of biomedical relevance.


Assuntos
1,2-Dipalmitoilfosfatidilcolina/química , Alameticina/farmacologia , Bicamadas Lipídicas/química , Sobrevivência Celular/efeitos dos fármacos , Células HeLa , Humanos , Difração de Raios X
5.
Environ Technol ; 35(9-12): 1462-9, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24701944

RESUMO

Activated sludge process is the most widely diffused system to treat wastewater to control the discharge of pollutants into the environment. Microorganisms are responsible for the removal of organic matter, nitrogen, phosphorous and other emerging contaminants. The environmental conditions of biological reactors significantly affects the ecology of the microbial community and, therefore, the performance of the treatment process. In the last years, ozone has been used to reduce excess sludge production by wastewater treatment plants (WWTPs), whose disposal represents one of the most relevant operational costs. The ozonation process has demonstrated to be a viable method to allow a consistent reduction in excess sludge. This study was carried out in a full-scale plant treating municipal wastewater in two parallel lines, one ozonated in the digestion tank and another used as a control. Bacterial communities of samples collected from both lines of digestion thanks were then compared to assess differences related to the ozonation treatment. Data were then analysed with terminal restriction fragment length polymorphism (T-RFLP) analysis on 16S rRNA gene. Differences between bacterial communities of both treated and untreated line appeared 2 weeks after the beginning of the treatment. Results demonstrated that ozonation treatment significantly affected the activated sludge in WWTP.


Assuntos
Consórcios Microbianos , Ozônio , Esgotos , Gerenciamento de Resíduos , Polimorfismo de Fragmento de Restrição
6.
Eur J Neurol ; 17(6): 774-9, 2010 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-20236307

RESUMO

Dementia is a terminal disease, associated with great suffering and difficult decisions in the severe stage. The decision-making process is characterized by uncertainty because of lack of scientific evidence in treatments and by the need to reconcile conflicting points of view. In intercurrent diseases, aggressive interventions are used without consideration of its futility; in comparison with cancer, several consequences of physicians' attitude not to consider dementia as a terminal disease have been reported, especially concerning pain relief. Lack of evidence of artificial nutrition and hydration effectiveness makes advance care planning relevant.


Assuntos
Demência/terapia , Cuidados Paliativos/ética , Assistência Terminal/ética , Tomada de Decisões , Humanos , Cuidados Paliativos/métodos , Guias de Prática Clínica como Assunto , Assistência Terminal/métodos
7.
Neurol Sci ; 28(4): 216-31, 2007 Aug.
Artigo em Inglês, Italiano | MEDLINE | ID: mdl-17690856

RESUMO

The document deals with some ethical issues raised by the treatment of demented people. In particular the conceptual and empirical aspects of the assessment of awareness and competence of these patients are analysed, as well as the dilemmas related to the treatment of behavioral disorders.


Assuntos
Cognição , Demência/psicologia , Ética Médica , Competência Mental , Transtornos Mentais , Autonomia Pessoal , Demência/terapia , Humanos , Autoimagem
8.
Toxicol In Vitro ; 15(2): 143-51, 2001 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-11287173

RESUMO

Herbicides are chemical compounds widely used in agriculture. As their intensive application is becoming a cause of environmental pollution, detailed and more sophisticated investigations are needed to understand better their consequences at the biological level. After herbicides are dispersed in the fields, they establish chemical interactions with both target and non-target plants. In both cases, herbicides can interact with the plant reproductive apparatus; consequently they could play a role during the fertilisation process in higher plants. Using an antibody to the alpha-tubulin subunit in immunofluorescence and immunoelectron microscopy techniques, we investigated the distribution of microtubules in Nicotiana tabacum pollen tubes grown under in vitro conditions in the presence of five different herbicides selected among those used frequently in central Italy. Herbicides have a specific effect on the microtubular apparatus of both pollen tube and generative cell. In addition to other tests and assays, these results suggest that the microtubule cytoskeleton of pollen tubes can be used as a bioindicator for studying the toxicity effects induced by herbicides.


Assuntos
Dicamba/efeitos adversos , Dicamba/toxicidade , Glicina/efeitos adversos , Herbicidas/efeitos adversos , Herbicidas/toxicidade , Microtúbulos/efeitos dos fármacos , Oxidiazóis/efeitos adversos , Oxidiazóis/toxicidade , Éteres Fenílicos/efeitos adversos , Pólen/efeitos dos fármacos , Testes de Toxicidade , Trifluralina/efeitos adversos , Imunofluorescência , Glicina/análogos & derivados , Éteres Difenil Halogenados , Imuno-Histoquímica , Técnicas In Vitro , Microscopia Confocal , Microscopia Imunoeletrônica , Microtúbulos/patologia , Plantas Tóxicas , Nicotiana , Glifosato
9.
J Reprod Med ; 45(10): 803-7, 2000 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-11077627

RESUMO

OBJECTIVE: To evaluate the effects of different management strategies for ectopic pregnancy on fertility. STUDY DESIGN: Retrospective cohort study of 180 consecutive patients who were diagnosed with ectopic pregnancy between September 1988 and December 1995. The fertility rate after ectopic pregnancy treated with surgery was compared with that after expectant treatment. Statistical analysis took into consideration the following confounding variables: history of sterility, infertility, ectopic pregnancy, use of intrauterine device, endometriosis, pelvic inflammatory disease or pelvic surgery prior to ectopic pregnancy, and type of therapy for ectopic pregnancy. RESULTS: Of the 180 women enrolled in the study, 97 desired conception. The intrauterine conception rate was similar in those initially treated expectantly as in those allocated to primary surgery (63% [31/49] vs. 51% [19/37], P = .37). Successful completion of expectant management was associated with rates of subsequent intrauterine pregnancy similar to those of surgical treatment (including primary surgery and surgery after failure of expectant management) (65% [22/34] vs. 54% [28/52], P = .44). Women undergoing delayed surgery due to failure of expectant management had rates of subsequent intrauterine conception similar to those who underwent primary surgery (9/15 vs. 19/37, P = .79). Several anamnestic factors had a significant and adverse effect on reproductive outcome: history of infertility (P = .01), history of ectopic pregnancy (P = .02) and previous pelvic surgery (P = .001). CONCLUSION: Expectant and surgical management of ectopic pregnancy had similar subsequent intrauterine conception rates, even when failure of expectant management led to secondary surgery. Gynecologic history can identify the subgroup of patients at higher risk of a poor reproductive outcome.


Assuntos
Fertilidade , Gravidez Ectópica/cirurgia , Estudos de Coortes , Feminino , Humanos , Gravidez , Estudos Retrospectivos
10.
Plant Cell ; 12(9): 1719-36, 2000 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-11006343

RESUMO

Pollen tube growth depends on the differential distribution of organelles and vesicles along the tube. The role of microtubules in organelle movement is uncertain, mainly because information at the molecular level is limited. In an effort to understand the molecular basis of microtubule-based movement, we isolated from tobacco pollen tubes polypeptides that cosediment with microtubules in an ATP-dependent manner. Major polypeptides released from microtubules by ATP (ATP-MAPs) had molecular masses of 90, 80, and 41 kD. Several findings indicate that the 90-kD ATP-MAP is a kinesin-related motor: binding of the polypeptide to microtubules was enhanced by the nonhydrolyzable ATP analog AMP-PNP; the 90-kD polypeptide reacted specifically with a peptide antibody directed against a highly conserved region in the motor domain of the kinesin superfamily; purified 90-kD ATP-MAP induced microtubules to glide in motility assays in vitro; and the 90-kD ATP-MAP cofractionated with microtubule-activated ATPase activity. Immunolocalization studies indicated that the 90-kD ATP-MAP binds to organelles associated with microtubules in the cortical region of the pollen tube. These findings suggest that the 90-kD ATP-MAP is a kinesin-related microtubule motor that moves organelles in the cortex of growing pollen tubes.


Assuntos
Microtúbulos/fisiologia , Nicotiana/fisiologia , Organelas/metabolismo , Plantas Tóxicas , Pólen/crescimento & desenvolvimento , Adenosina Trifosfatases/metabolismo , Trifosfato de Adenosina/farmacologia , Transporte Biológico/efeitos dos fármacos , Fracionamento Químico , Immunoblotting , Cinesinas/análise , Microscopia de Fluorescência , Peptídeos/metabolismo , Proteínas de Plantas/metabolismo , Pólen/ultraestrutura , Ligação Proteica , Nicotiana/citologia
11.
Eur J Cell Biol ; 67(3): 209-17, 1995 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-7588877

RESUMO

Using anti-myosin antibodies, standard immunocytochemical techniques in conjunction with confocal scanning laser microscopy and colloidal gold immunoelectron microscopy we compare changes in the distribution patterns of myosin during the early stages of pollen hydration, germination, tube growth, and myosin associated with isolated vegetative nucleus and the generative cell in Nicotiana tabacum L. Furthermore, on the Western blots of pollen tube proteins, the antimyosin antibodies crossreact only with one polypeptide of approximately 174 kDa. Confocal immunofluorescence microscopy reveals that in hydrated pollen, myosin is discretely associated with the cytoplasmic organelles and numerous punctate structures present in the center of the pollen. Within 30 min following transfer of pollen into the germination medium, that is, with the onset of germination, the centrally located punctate structures are displaced, and we find accumulation of myosin-associated organelles towards one of the germinal apertures from which the pollen tube would emerge. Subsequently, after 45 min of germination with the emergence of germination structure, few punctate structures are detected in the vegetative cytoplasm while intense immunostain is detected just below the plasma membrane of the emerging pollen tube tip. In the older parts of both short and long pollen tubes after 90 to 120 min of pollen germination, few fluorescent structures were found in the pollen tubes, however, numerous punctate fluorescent spots were concentrated in the tip region over a distance of 2 to 3 microns below the plasma membrane of the tube tip. This is further substantiated by colloidal gold immunoelectron microscopy wherein clusters of gold particles are associated with vesicle-like structures in the tip region of the pollen tubes.(ABSTRACT TRUNCATED AT 250 WORDS)


Assuntos
Germinação , Miosinas/isolamento & purificação , Nicotiana/ultraestrutura , Plantas Tóxicas , Pólen/ultraestrutura , Western Blotting , Núcleo Celular/ultraestrutura , Imunofluorescência , Ouro , Processamento de Imagem Assistida por Computador , Lasers , Microscopia Confocal , Microscopia Imunoeletrônica , Miosinas/imunologia , Pólen/química , Pólen/crescimento & desenvolvimento , Nicotiana/química , Nicotiana/citologia , Água
12.
J Cell Sci ; 108 ( Pt 3): 1117-25, 1995 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-7622598

RESUMO

Nicotiana tabacum pollen tubes contain two high molecular weight polypeptides (about 400 kDa), which are specifically expressed during pollen germination and pollen tube growth in BK medium. The high molecular weight doublet resembles the dynein heavy chains in some biochemical properties. Sedimentation profiles of pollen tube extracts show that the high molecular weight bands have sedimentation coefficients of 22 S and 12 S, respectively. ATPase assay of sedimentation fractions shows an activity ten times higher when stimulated by the presence of bovine brain microtubules in fractions containing the 22 S high molecular weight polypeptide. Both these high molecular weight polypeptides can bind microtubules in an ATP-dependent fashion. A mouse antiserum to a synthetic peptide reproducing the sequence of the most conserved ATP-binding site among dynein heavy chains recognized the two high molecular weight polypeptides. Therefore these polypeptides have sequences immunologically related to the ATP binding sites of dynein heavy chains.


Assuntos
Dineínas/química , Nicotiana/química , Proteínas de Plantas/química , Plantas Tóxicas , Adenosina Trifosfatases/metabolismo , Trifosfato de Adenosina/metabolismo , Sequência de Aminoácidos , Animais , Anticorpos , Sítios de Ligação , Encéfalo/metabolismo , Bovinos , Dineínas/genética , Dineínas/metabolismo , Imunoquímica , Técnicas In Vitro , Microtúbulos/metabolismo , Dados de Sequência Molecular , Peso Molecular , Peptídeos/síntese química , Peptídeos/química , Peptídeos/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Pólen/química , Nicotiana/genética , Nicotiana/metabolismo
13.
Biol Cell ; 83(2-3): 179-84, 1995.
Artigo em Inglês | MEDLINE | ID: mdl-7549913

RESUMO

The specificity of four monoclonal antibodies, raised against mammalian ciliary axonemes, was determined by both immunofluorescence and immunoblot experiments. Three antibodies reacted with epitopes which are differentially located along axonemal length. Among these, antibody 3.12 recognized an epitope common to different dynein heavy chains, reacted only with tracheal cilia and specifically stained the proximal portion of the ciliary axoneme.


Assuntos
Anticorpos Monoclonais/imunologia , Cílios/imunologia , Animais , Bovinos , Cílios/química , Cílios/ultraestrutura , Técnicas Imunoenzimáticas , Técnicas In Vitro , Peso Molecular , Traqueia/ultraestrutura
14.
Zygote ; 2(1): 63-8, 1994 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-7881918

RESUMO

Using monoclonal anti-calmodulin antibodies in conjunction with confocal scanning laser microscopy we have analysed the spatial variations in the distribution pattern of calmodulin (CaM) during the sequential events of pollen hydration, germination and tube growth in Nicotiana tabacum. These immunocytochemical observations have been complemented by immunochemical studies wherein the anti-calmodulin antibody raised against pea CaM recognises a polypeptide of c. 18 kDa in the pollen extracts. Digitisation of confocally acquired optical sections of immunofluorescence images reveals that in hydrated pollen a high level of CaM is consistently present in the region of the germinal apertures. Subsequently, with the onset of germination a high CaM concentration was found associated with the plasma membrane of the germination bubble and in the cytoplasm in its vicinity, while in the vegetative cytoplasm a weak diffuse and intense punctate signal was registered. CaM immunostain was also detected in association with the plasma membrane of the tube tips in both short and long pollen tubes. Furthermore, the cytosol of the tubes invariably manifested an apically focused CaM gradient. We were, however, unable to detect any vacuolar association of CaM in the older regions of the pollen tubes. Although punctate immunostain was obvious across the pollen tube numerous punctate structures were invariably present in the extreme tip. The possible implications of these findings in development of cell polarity, polarised growth, maintenance of calcium homeostasis and CaM interactions with other mechanochemical motor proteins in effecting propulsion of organelles during pollen hydration, germination and pollen tube growth are discussed.


Assuntos
Calmodulina/metabolismo , Germinação , Nicotiana/crescimento & desenvolvimento , Plantas Tóxicas , Western Blotting , Calmodulina/genética , Processamento de Imagem Assistida por Computador , Imuno-Histoquímica , Microscopia Confocal , Microscopia de Fluorescência , Pólen , Nicotiana/genética , Nicotiana/fisiologia , Água
15.
Cell Motil Cytoskeleton ; 29(2): 155-66, 1994.
Artigo em Inglês | MEDLINE | ID: mdl-7820865

RESUMO

A 100-kDa polypeptide with microtubule-interacting properties was identified in a Golgi vesicle-enriched fraction from Corylus avellana pollen. The k71s23 antibody (directed to the kinesin heavy chain from bovine brain) [Tiezzi et al., 1992: Cell Motil. Cytoskeleton 21:132-137] localized the polypeptide on the external surface of membrane-bounded organelles. Some 100-kDa-containing vesicles copelleted with microtubules (polymerized from purified bovine brain tubulin) either in presence or absence of 5 mM AMPPNP, but they could be released by 10 mM ATP or 0.5 M KCl. The pollen microtubule-interacting protein, salt-extracted from membranes and partially purified by gel filtration, exhibited an ATPase activity (16.2 nmolPi/mg/min) which could be stimulated about 2-fold (32.5 nmolPi/mg/min) by addition of bovine brain microtubules. We suppose that the 100-kDa polypeptide is part of a molecular complex showing properties of the kinesin class.


Assuntos
Complexo de Golgi/química , Cinesinas/análise , Pólen/química , Animais , Bovinos , Centrifugação com Gradiente de Concentração , Cromatografia em Gel , Eletroforese em Gel de Poliacrilamida , Complexo de Golgi/metabolismo , Complexo de Golgi/fisiologia , Imuno-Histoquímica , Cinesinas/metabolismo , Cinesinas/fisiologia , Microscopia Imunoeletrônica , Microtúbulos/química , Microtúbulos/metabolismo , Microtúbulos/fisiologia , Peso Molecular , Organelas/química , Organelas/metabolismo , Organelas/fisiologia , Pólen/ultraestrutura , Árvores , Tubulina (Proteína)/análise , Tubulina (Proteína)/metabolismo , Tubulina (Proteína)/fisiologia
16.
Toxicol In Vitro ; 8(6): 1277-83, 1994 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-20693100

RESUMO

The exposure of 3T3 mouse fibroblasts to vinyl-4-cyclohexene dioxide (VCD), a compound used as a chemical intermediate and as a reactive diluent for diepoxides and epoxy resins, induces changes in cellular shape and cytoplasmic organization. Toxicological effects on the cytoskeletal elements were investigated by culturing 3T3 cells in medium containing VCD for increasing times (15, 30, 60 and 180 min). The immunofluorescence investigations demonstrated that both vimentin-containing intermediate filaments and microtubules were compromised by the treatment in a time-dependent manner. Increasing the duration of exposure to VCD increased cellular damage.

17.
Zygote ; 1(2): 143-54, 1993 May.
Artigo em Inglês | MEDLINE | ID: mdl-8081810

RESUMO

The cytoskeletal organisation of the isolated embryo sac and egg cells of Plumbago zeylanica was examined before, during and after pollen tube penetration into the embryo sac to determine the potential involvement of microtubules and actin filaments in fertilisation. Material was singly and triply stained using Hoechst 33258 to localise DNA, fluorescein isothiocyanate (FITC)-labelled anti-alpha-tubulin to detect microtubules and rhodamine-phalloidin to visualise F-actin. Microtubules in the unfertilised egg cell are longitudinally aligned in the micropylar and mid-lateral areas, aggregating into bundles near the filiform apparatus. In the perinuclear cytoplasm of the egg cell, microtubules become more or less randomly aligned. F-actin bundles form a longitudinally aligned mesh in the chalazal cytoplasm of the egg cell. In the central cell, microtubules and F-actin are distributed along transvacuolar strands and are also evident in the perinuclear region and at the periphery of the cell. During pollen tube penetration, sparse microtubule bundles near the pathway of the pollen tube may form an apparent microtubular 'conduit' surrounding the male gametes at the delivery site. Actin aggregates become organised near the pathway of the pollen tube and at the delivery site of the sperm cells. Subsequently, actin aggregates form a 'corona' structure in the intercellular region between the egg and central cell where gametic fusion occurs. The corona may have a role in maintaining the close proximity of the egg and central cell and helping the two sperm cells move and bind to their target cells. The cytoskeleton may also be involved in causing the two nuclei of the egg and central cell to approach one another at the site of gametic fusion and transporting the two sperm nuclei into alignment with their respective female nucleus. The cytoskeleton is reorganised during early embryogenesis.


Assuntos
Plantas/ultraestrutura , Citoesqueleto/fisiologia , Citoesqueleto/ultraestrutura , Fertilização/fisiologia , Óvulo/ultraestrutura , Fenômenos Fisiológicos Vegetais , Pólen/ultraestrutura , Zigoto/ultraestrutura
18.
Cell Motil Cytoskeleton ; 21(2): 132-7, 1992.
Artigo em Inglês | MEDLINE | ID: mdl-1559264

RESUMO

A cytoskeletal apparatus is involved in the movement of vesicles, organelles, and gametes in the pollen tube. The function of microfilaments has been defined quite precisely, but the role of microtubules needs to be further clarified. On the basis of immunological and biochemical investigations, we have identified a polypeptide showing common properties with kinesin, a microtubule-based motor mainly described in nonplant tissues, in the pollen tube of Nicotiana tabacum. Like mammalian kinesin, the kinesin-immunoreactive homolog from Nicotiana tabacum pollen tubes binds to mammalian microtubules in an AMP-PNP dependent manner. The kinesin-like component is likely to be involved in the movement of vesicular material in the growing pollen tube.


Assuntos
Cinesinas/química , Nicotiana/química , Plantas Tóxicas , Pólen/química , Adenilil Imidodifosfato , Anticorpos Monoclonais , Sítios de Ligação , Western Blotting , Movimento Celular , Cinesinas/metabolismo , Microscopia de Fluorescência , Microtúbulos/química , Nicotiana/metabolismo
19.
Electron Microsc Rev ; 4(2): 205-19, 1991.
Artigo em Inglês | MEDLINE | ID: mdl-1932581

RESUMO

In the last few years the role of pollen and the pollen tube in the fertilization process in higher plants has received considerable attention. By ultrastructural, biochemical and immunofluorescent investigations it has been shown that a cytoskeletal apparatus plays a central role in pollen tube growth. Microfilaments and microtubules, in which main components are, respectively, actin and tubulin, represent the most investigated cytoskeletal components. New information has been recently provided by the identification of myosin and also of a kinesin-like protein. The pollen tube cytoskeleton consists of two different cytoskeletal systems: the vegetative cell cytoskeleton, namely the cytoskeleton of the pollen grain and pollen tube, and the gamete cytoskeleton (generative cell and sperm cell cytoskeleton). The vegetative cell cytoskeleton plays a fundamental role in assuring the cytoplasmic movement of organelles, vesicles and gametes from the pollen grain to the pollen tube apex and consists mainly of microtubules and microfilaments. Also myosin and the kinesin-like protein are involved in the process of organelle and vesicle movement. The gamete cytoskeleton has a central role in sperm cell formation and in the reshaping process during gamete movement inside the pollen tube. It consists mostly of microtubules and partially characterized microtubule-associated structures. Actin filaments have recently also been identified.


Assuntos
Citoesqueleto/ultraestrutura , Pólen/ultraestrutura , Animais , Fertilização , Microscopia Eletrônica , Plantas/ultraestrutura
20.
Planta ; 181(3): 304-9, 1990 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24196806

RESUMO

The vegetative nucleus (VN) of Nicotiana tabacum L. has been qualitatively and quantitatively studied in fresh, hydrated, and activated pollen. Techniques included the use of optical sectioning by confocal scanning laser microscopy to obtain volume and surface area measurements, and stereoscopic pairs; and freeze-etch electron microscopy to estimate the frequency of nuclear pores per µm(2) in the vegetative nucleus. Several morphological changes were observed to occur in pollen grain nuclei during the early processes of tube growth. In freshly dehisced pollen grain, the vegetative and generative nuclei were side by side, but following hydration and activation of the grain, the elongated generative nucleus became partially surrounded by the vegetative nucleus. It was found that during hydration, the surface area of the vegetative nucleus increased and there was a decrease in the frequency of nuclear pores. The calculated total number of pores remained similar. After activation and pollen-tube growth, the vegetative nucleus retained the same surface area as in the hydrated state but the frequency of nuclear pores decreased; therefore, the calculated total number of pores was significantly lowered. When considered alongside complementary biochemical data, these morphological results indicate that RNA production in the vegetative nucleus decreases following germination.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...