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1.
Arch Virol ; 162(7): 1833-1843, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28283816

RESUMO

The poultry industry has emerged as one of the largest and fastest growing public sectors in the developed and developing countries. Unfortunately, this industry is under a major threat from diseases that are viral (Newcastle disease, infectious bursal disease, influenza, hydropericardium syndrome), bacterial (colibacillosis, pasteurellosis, salmonellosis, mycoplasmosis), parasitic (coccidiosis, histoplasmosis) or nutritional (dyschondroplasia, osteoporosis). Among these diseases, hydropericardium syndrome (HPS) is one of the important emerging diseases occurring in the specific areas of the world where broilers (chickens) are reared under intensive conditions. HPS was first observed in 1987 at Angara Goth, an area near Karachi, Pakistan, where broilers are raised. Since then, HPS has been reported in many countries of the world. From these reported cases, an adenovirus that was either isolated from or visualized electron microscopically in the liver of affected broilers has been implicated in the syndrome. The syndrome has been reproduced by inoculation of isolated fowl adenovirus (FAdV) strains, and hence, the syndrome is also called infectious hydropericardium syndrome. To our knowledge, HPS has not been observed in humans, so it is not considered a zoonotic disease, but it is of economic importance and causes huge losses to the poultry industry. Efforts have been made to develop conventional vaccines against this disease, which were formulated from infected liver homogenate. Formalin-inactivated liver organ vaccines have failed to protect the poultry industry. Hence, there is a dire need to develop a suitable vaccine to combat this disease. Currently, recombinant vaccine candidates are being developed by using molecular biology and biotechnological approaches for the prevention and control of infectious diseases, including HPS. Therefore, it is suggested that the immunogenicity of these recombinant proteins should be evaluated for their use as subunit vaccines.


Assuntos
Infecções por Adenoviridae/veterinária , Adenovirus A das Aves/fisiologia , Doenças das Aves Domésticas/prevenção & controle , Vacinas Virais/imunologia , Infecções por Adenoviridae/prevenção & controle , Infecções por Adenoviridae/virologia , Animais , Aves Domésticas , Doenças das Aves Domésticas/virologia
2.
Biologicals ; 44(1): 19-23, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26558992

RESUMO

Fowl adenovirus-4 is an infectious agent causing Hydropericardium syndrome in chickens. Adenovirus are non-enveloped virions having linear, double stranded DNA. Viral genome codes for few structural and non structural proteins. 100K is an important non-structural viral protein. Open reading frame for coding sequence of 100K protein was cloned with oligo histidine tag and expressed in Escherichia coli as a fusion protein. Nucleotide sequence of the gene revealed that 100K gene of FAdV-4 has high homology (98%) with the respective gene of FAdV-10. Recombinant 100K protein was expressed in E. coli and purified by nickel affinity chromatography. Immunization of chickens with recombinant 100K protein elicited significant serum antibody titers. However challenge protection test revealed that 100K protein conferred little protection (40%) to the immunized chicken against pathogenic viral challenge. So it was concluded that 100K gene has 2397 bp length and recombinant 100K protein has molecular weight of 95 kDa. It was also found that the recombinant protein has little capacity to affect the immune response because in-spite of having an important role in intracellular transport & folding of viral capsid proteins during viral replication, it is not exposed on the surface of the virus at any stage.


Assuntos
Infecções por Adenoviridae , Adenoviridae , Proteínas do Capsídeo , Galinhas , Genes Virais/imunologia , Imunização , Doenças das Aves Domésticas , Adenoviridae/genética , Adenoviridae/imunologia , Infecções por Adenoviridae/genética , Infecções por Adenoviridae/imunologia , Infecções por Adenoviridae/prevenção & controle , Infecções por Adenoviridae/veterinária , Infecções por Adenoviridae/virologia , Animais , Proteínas do Capsídeo/genética , Proteínas do Capsídeo/imunologia , Proteínas do Capsídeo/farmacologia , Galinhas/imunologia , Galinhas/virologia , Clonagem Molecular , Doenças das Aves Domésticas/genética , Doenças das Aves Domésticas/imunologia , Doenças das Aves Domésticas/prevenção & controle , Doenças das Aves Domésticas/virologia
3.
Environ Entomol ; 44(3): 780-8, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-26313984

RESUMO

The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama is a key pest of citrus due to its role as vector of citrus greening disease or "huanglongbing." ACP monitoring is considered an indispensable tool for management of vector and disease. In the present study, datasets collected between 2009 and 2013 from 245 citrus blocks were used to evaluate precision, sensitivity for detection, and efficiency of five sampling methods. The number of samples needed to reach a 0.25 standard error-mean ratio was estimated using Taylor's power law and used to compare precision among sampling methods. Comparison of detection sensitivity and time expenditure (cost) between stem-tap and other sampling methodologies conducted consecutively at the same location were also assessed. Stem-tap sampling was the most efficient sampling method when ACP densities were moderate to high and served as the basis for comparison with all other methods. Protocols that grouped trees near randomly selected locations across the block were more efficient than sampling trees at random across the block. Sweep net sampling was similar to stem-taps in number of captures per sampled unit, but less precise at any ACP density. Yellow sticky traps were 14 times more sensitive than stem-taps but much more time consuming and thus less efficient except at very low population densities. Visual sampling was efficient for detecting and monitoring ACP at low densities. Suction sampling was time consuming and taxing but the most sensitive of all methods for detection of sparse populations. This information can be used to optimize ACP monitoring efforts.


Assuntos
Citrus , Hemípteros/fisiologia , Controle de Insetos/métodos , Animais , Citrus/crescimento & desenvolvimento , Florida , Densidade Demográfica
4.
Bull Entomol Res ; 104(5): 576-85, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-24830653

RESUMO

The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama is considered a key citrus pest due to its role as vector of 'huanglongbing' (HLB) or citrus greening, probably the most economically damaging disease of citrus. Insecticidal control of the vector is still considered a cornerstone of HLB management to prevent infection and to reduce reinoculation of infected trees. The severity of HLB has driven implementation of intensive insecticide programs against ACP with unknown side effects on beneficial arthropod fauna in citrus agroecosystems. We evaluated effects of calendar sprays directed against this pest on natural enemy assemblages and used exclusion to estimate mortality they imposed on ACP populations in citrus groves. Predator exclusion techniques were used on nascent colonies of D. citri in replicated large untreated and sprayed plots of citrus during the four major flushing periods over 2 years. Population of spiders, arboreal ants and ladybeetles were independently assessed. Monthly sprays of recommended insecticides for control of ACP, adversely affected natural enemy populations resulting in reduced predation on ACP immature stages, especially during the critical late winter/early spring flush. Consequently, projected growth rates of the ACP population were greatest where natural enemies had been adversely affected by insecticides. Whereas, this result does not obviate the need for insecticidal control of ACP, it does indicate that even a selective regimen of sprays can impose as yet undetermined costs in terms of reduced biological control of this and probably other citrus pests.


Assuntos
Citrus , Hemípteros , Inseticidas/efeitos adversos , Animais , Controle de Insetos/métodos , Controle Biológico de Vetores , Comportamento Predatório/efeitos dos fármacos , Aranhas/efeitos dos fármacos , Aranhas/fisiologia
5.
Vaccine ; 30(50): 7153-6, 2012 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-23085359

RESUMO

Hydropericardium syndrome (HPS) is a disease of poultry that is caused by fowl adenovirus-4. Inactivated liver homogenate from diseased birds is still the choice of vaccine in some countries which disseminates numerous pathogens along with inactivated virus. Moreover incomplete attenuation or inactivation, reversion to virulence and the oncogenic potential/genetic instability of the adenoviruses have prevented their use in routine vaccines. To address this problem an effort is made to develop a subunit vaccine. For this purpose penton base protein of HPS virus was expressed in Escherichia coli and used as subunit vaccine in broilers. Immunogenicity of the recombinant penton base protein and challenge protection test against pathogenic virus demonstrated the ability of recombinant penton base protein to confer (90%) protection. Results suggest that the recombinant penton base protein is a candidate for subunit vaccine against HPS.


Assuntos
Infecções por Adenoviridae/veterinária , Proteínas do Capsídeo/imunologia , Pericardite/veterinária , Doenças das Aves Domésticas/prevenção & controle , Vacinas Virais/imunologia , Infecções por Adenoviridae/prevenção & controle , Animais , Proteínas do Capsídeo/administração & dosagem , Escherichia coli/genética , Expressão Gênica , Pericardite/prevenção & controle , Aves Domésticas , Vacinas de Subunidades/administração & dosagem , Vacinas de Subunidades/imunologia , Vacinas Sintéticas/administração & dosagem , Vacinas Sintéticas/imunologia , Vacinas Virais/administração & dosagem
6.
East Mediterr Health J ; 16 Suppl: S106-13, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-21495596

RESUMO

This paper illustrates the experiences of essential medicine management in providing cure and care to victims of Pakistan's 2005 earthquake in a safe, rational and effective mode. The health interventions assured access to essential medicine, sustained supply, inventory control through a computerized logistic support system and rational use of medicines. World Health Organization Pakistan outlined modalities for acceptance of donated medicines, assisted in speedy procurement of medicines and designed customized kits. Proper storage of medicines at controlled temperature was ensured in warehousing facilities in 12 locations. A steady supply of medicines and their consumption without stock-outs in the 56 first-level care facilities of calamity-hit areas helped to ascertain the average consumption and cost of essential medicines and supplies for the catchment population. Tools for quantification and forecasting of medicines and supplies were developed and shared. Medicines and medical supplies were efficiently used resulting in minimum wastage.


Assuntos
Medicina de Desastres/métodos , Medicamentos Essenciais/provisão & distribuição , Emergências , Desastres , Terremotos , Humanos , Paquistão
7.
East Mediterr Health J ; 16 Suppl: S159-66, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-21495602

RESUMO

Organ transplantation must be viewed in relation to the prevailing cultural, religious and economic conditions of a nation. Over the past two decades, Pakistan has emerged as one of the largest centres for commercial renal transplantation. Government efforts, supported by professional associations, civil society organizations and the media, along with World Health Organization technical assistance, have led to the development of legislation regulating this practice and curbing organ trade in conformity with international guidelines. Although only two years have passed since the enactment of the law, there is evidence that conditions have significantly improved, raising hopes for ethical and safe organ transplantation in Pakistan. This study reviews the salient features of the legislation and lists the foreseeable evolving challenges and opportunities.


Assuntos
Regulamentação Governamental , Transplante de Órgãos/legislação & jurisprudência , Doadores de Tecidos/legislação & jurisprudência , Humanos , Paquistão , Doadores de Tecidos/ética
8.
J Econ Entomol ; 102(6): 2325-32, 2009 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-20069864

RESUMO

The genetic diversity of Tamarixia radiata Waterston (Hymenoptera: Eulophidae) laboratory colonies derived from collections in China, northern Vietnam, Pakistan, and a mixed colony from Taiwan and southern Vietnam was evaluated using the internal transcribed spacer (ITS) region 1, ITS-2, and the 5' end of the cytochrome oxidase subunit I gene. The strains share the same ITS sequence, consistent with the morphological hypothesis that the collections represent a single species. The COI marker was variable and could distinguish the northern Vietnam and Pakistan colonies from each other and from the other colonies. Comparison of COI sequences from field-collected populations of Puerto Rico, Guadeloupe, and Texas indicates that Florida is not a likely source of the introduction into Puerto Rico but is a likely source of the introduction into Texas.


Assuntos
Complexo IV da Cadeia de Transporte de Elétrons/genética , Variação Genética , Hemípteros/parasitologia , Controle Biológico de Vetores , Vespas/genética , Animais , Ásia , Citrus/parasitologia , DNA Espaçador Ribossômico/genética , Especiação Genética , Interações Hospedeiro-Parasita , Murraya/parasitologia
9.
Community Genet ; 11(1): 68-70, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18196920

RESUMO

BACKGROUND: We report cascade testing of a large Pakistani family for beta-thalassemia alleles. The family was still practicing consanguineous marriages and was at risk of having more affected births. OBJECTIVE: The objective of this study was to show that identification of disease carriers in families with index cases in order to create awareness about disease and provide genetic counseling would result in reduction of the frequency of beta-thalassemia in Pakistan. METHODS: In this large family with an index case, 27 available living members were tested for beta-thalassemia. Carriers of the disease were detected by measuring hemoglobin indices, and amplification refractory mutation system polymerase chain reaction was used for mutation analysis. Genetic counseling was provided to members of this family. RESULTS: There were already 3 marriages between the carrier members and 1 between a carrier and noncarrier in this large family; 12 (44.4%) members were found to carry the mutant gene, representing a very high carrier rate compared to the 5.4% carrier frequency of beta-thalassemia in the general population of Pakistan. The family was counseled for prevention of affected births. The initially reluctant family gradually became cooperative and seriously attended the genetic counseling sessions. CONCLUSION: Cascade testing is more practical than general population screening in a country with limited health facilities where consanguineous marriages are practiced. This report emphasizes the need of extensive testing within families with index cases to identify the carriers of beta-thalassemia in order to reduce disease occurrence through awareness and genetic counseling.


Assuntos
Testes Genéticos/métodos , Talassemia beta/diagnóstico , Talassemia beta/genética , Consanguinidade , Análise Mutacional de DNA , Saúde da Família , Feminino , Frequência do Gene , Heterozigoto , Humanos , Masculino , Mutação , Paquistão , Linhagem , Risco , Talassemia beta/etnologia , Talassemia beta/prevenção & controle
10.
Arch Virol ; 153(1): 163-70, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18030544

RESUMO

Chronic hepatitis B virus (HBV) infection remains a major health issue worldwide. Several factors including core gene variation are responsible for the development of chronicity of HBV infection. The present study was designed to identify the variations in the core region of the HBV genome in a local population of chronic hepatitis B patients (n = 57) using a PCR-based restriction fragment length polymorphism (PCR-RFLP) method. Fifty subjects were found to be positive for the presence of HBV DNA. For the core region genotyping, the Ava II and Msp I restriction enzymes were used. Mutations at nucleotide (nt) 2147 and nt 2362 in the HBV genome in the core region for Ava II (A4 type, 74%) and nt 2331 for Msp I (M1 type, 66%) were observed as the most common pattern. These results are different from those of previously reported studies on other populations and thus appear to be unique to the Pakistani population. This type of characterization of core mutants may be useful for the design of vaccines based on viral epitopes that are effective for the Pakistani population. Moreover, these unique genotypic patterns for the HBV core gene might be some of the main factors responsible for understanding the underlying mechanism by which HBV chronicity is developed in the Pakistani population.


Assuntos
DNA Viral/análise , Genótipo , Antígenos do Núcleo do Vírus da Hepatite B/genética , Vírus da Hepatite B/classificação , Hepatite B Crônica/virologia , Polimorfismo de Fragmento de Restrição , Vírus da Hepatite B/genética , Vírus da Hepatite B/isolamento & purificação , Humanos , Paquistão , Reação em Cadeia da Polimerase , Mapeamento por Restrição
11.
J Econ Entomol ; 99(4): 1214-24, 2006 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-16937675

RESUMO

Changes in fitness parameters as a function of colony size (one versus 10 aphids) were measured in two biotypes (RWA1 and RWA2) of the Russian wheat aphid, Diuraphis noxia (Mordvilko) (Homoptera: Aphididae), feeding on three cultivars of wheat, Triticum aestivum L., at two temperatures. 'Trego' is a cultivar with no specific resistance to D. noxia, whereas, 'Stanton' and 'Halt' express Dny and Dn4 resistance sources, respectively. Feeding in a group accelerated the development of RWA1 on Trego and Stanton at 20 degrees C, but not at 24 degrees C, whereas grouped RWA2 developed faster than solitary RWA2 on all three cultivars at 24 degrees C, but not at 20 degrees C. Survival (first instar-adult) of RWA2 also was improved by grouping on Stanton and Halt at 24 degrees C, but solitary RWA2 survived better at 20 degrees C on all three cultivars. The reproductive rate of RWA1 was improved by grouping on Trego and Stanton at both temperatures, but only on Halt at 24 degrees C. Lifetime fecundity of RWA1 also was increased by grouping in all cases except for Trego at 20 degrees C. Grouped development increased the reproductive rate of RWA2 on all three cultivars at 24 degrees C, but had no effect at 20 degrees C. Grouped RWA2 developed and reproduced faster than grouped RWA1 on all three cultivars at 24 degrees C. Thus, the fitness of D. noxia was positively correlated with group size during colony establishment, but the effects were sensitive to temperature, being more pronounced at 20 degrees C for RWA1 and at 24 degrees C for RWA2.


Assuntos
Afídeos/fisiologia , Triticum/parasitologia , Animais , Afídeos/crescimento & desenvolvimento , Densidade Demográfica , Reprodução/fisiologia
12.
Ann Saudi Med ; 19(4): 337-40, 1999.
Artigo em Inglês | MEDLINE | ID: mdl-17277535

RESUMO

BACKGROUND: Typhoid is a common problem in developing countries. Cultivation of bacteria and serology (especially Widal test) give unacceptable levels of false-negative and false-positive results, respectively. PATIENTS AND METHODS: In this study, a recently introduced polymerase chain reaction-based technique (which has 100% specificity for Salmonella typhi) was compared with blood culture and Widal test during the first week of illness of 82 suspected cases of typhoid. RESULTS: The respective figures of positivity for PCR, blood culture and Widal test were 71.95%, 34.1%, and 36.5%. A control group of 20 healthy persons gave figures of 0%, 0%, and 33.3%, respectively. CONCLUSION: We conclude that this PCR-based technique is not only absolutely specific, but also very sensitive and, therefore, much superior to blood culture and Widal test for the early diagnosis of typhoid.

13.
J Pak Med Assoc ; 47(7): 178-81, 1997 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-9301157

RESUMO

Dengue is a mosquito borne disease with worldwide distribution. Depending on virulence factors and host immune status, infection can manifest as a severe but non fatal viral syndrome or a rapidly progressive and a frequently fatal haemorrhagic fever. During the course of an outbreak of viral fever in Karachi, Pakistan from June, 1994 to September, 1995, we studied 145 cases admitted at the Aga Khan University Hospital. 43% of the cases were between the age group of 20-30 years, majority of these being male (75%). Amongst the clinical signs and symptoms, the most frequent findings were fever, vomiting and abdominal pain. Spontaneous hemorrhagic manifestations occurred in 66 patients and of these petechiae and mucosal bleed were the commonest, that is, 42% and 38% respectively. At presentation thrombocytopenia (platelet count < or = 50,000) per cubic millimeter) was present in 78%, leucopenia (white cell count < 4,000 per cubic millimeter) in 34%. Apart from one patient who died from hemorrhagic shock on the 5th day of admission, the remaining patients recovered and their platelet counts normalized on an average in 9 days. This is the first reported epidemic in Karachi of dengue infection.


Assuntos
Dengue/epidemiologia , Surtos de Doenças , Adulto , Dengue/complicações , Dengue/prevenção & controle , Feminino , Humanos , Masculino , Controle de Mosquitos , Paquistão/epidemiologia , Gravidez , Estudos Retrospectivos , Estudos Soroepidemiológicos , Trombocitopenia/etiologia
14.
J Gastroenterol Hepatol ; 12(11): 703-6, 1997 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-9430033

RESUMO

In order to determine whether obstructive pancreatobiliary lesions increase the risk of duodenal erosions and ulcers, the duodenal mucosa of patients with these lesions were prospectively examined before endoscopic retrograde cholangiopancreatography (ERCP). During the study period, 133 patients underwent ERCP for various reasons in the Department of Medicine, The Aga Khan University Hospital. One hundred and twenty-three patients were eligible for final analysis. Sixty-five patients with bilirubin > or = 35 mumol/L and alkaline phosphatase > or = 2.5 times normal levels along with radiological evidence of pancreatobiliary obstruction were included in the obstruction group. Fifty-eight patients who did not fulfil these criteria were used in the control group. Acid peptic lesions, which included erosions and ulcers, were seen in 16 patients of the obstruction group and four patients of the control group (P = 0.016, odds ratio (OR) = 4.41). Patients with carcinoma of the pancreas had a greater number of lesions than the rest of the obstruction group (P = 0.001, OR = 8.75). Individual variables like age, sex, serum bilirubin, alanine aminotransferase, alkaline phosphatase, amylase levels, and duration of jaundice did not increase the vulnerability to acid peptic injury. The degree of obstruction multiplied by duration of jaundice (alkaline phosphatase x days) increased the susceptibility for duodenal disease (P = 0.047). From this data it was concluded that patients with obstructive pancreatobiliary lesions are more prone to acid peptic duodenal lesions.


Assuntos
Colestase/complicações , Duodenopatias/etiologia , Úlcera Duodenal/etiologia , Duodeno/patologia , Pancreatopatias/complicações , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Colangiopancreatografia Retrógrada Endoscópica , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
15.
Oncogene ; 11(7): 1249-54, 1995 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-7478544

RESUMO

We used PCR amplification of tandem repeats to study the pattern of allelic loss in borderline and invasive ovarian epithelial tumors using 12 primer pairs to generate a detailed deletion map of chromosome 9p. In the invasive ovarian carcinomas, there were three regions displaying high frequency of loss of heterozygosity (LOH) ranging from 31-38%. In contrast, LOH was a rare event among the borderline ovarian tumors, with one region revealing a rate of 20% and the remaining regions only 0-8% LOH. Therefore, allelic loss does not seem to be important for the development of borderline ovarian tumors. We also examined p16 gene expression and mutations in ovarian cancer cell lines and invasive and borderline ovarian tumor tissues. Southern blot analysis revealed no losses of the p16 gene in either the invasive or borderline ovarian tumors. However, the ovarian carcinoma cell lines showed a 50% homozygous deletion rate. SSCP analysis detected a mobility shift in only one (borderline) tumor. Since the primary invasive ovarian tumors did not show any deletions or mutations, it appears that p16 does not play a role in the pathogenesis of these tumors.


Assuntos
Proteínas de Transporte/genética , Deleção Cromossômica , Cromossomos Humanos Par 9 , Invasividade Neoplásica/genética , Neoplasias Ovarianas/genética , Linhagem Celular Transformada , Células Cultivadas , Mapeamento Cromossômico , Inibidor p16 de Quinase Dependente de Ciclina , Feminino , Heterozigoto , Humanos , Neoplasias Ovarianas/patologia , Ovário/citologia , Ovário/metabolismo , Reação em Cadeia da Polimerase
16.
Plant Cell Rep ; 12(2): 89-94, 1993 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24202075

RESUMO

Spring wheat (Triticum aestivum L.) zygotic embryos were successfully cryopreserved, without the addition of exogenous cryoprotectants, using only an abscisic acid (ABA) pretreatment. Optimum survival was obtained when embryos were cultured in vitro for 10 days on semisolid Murashige and Skoog (MS) nutrient medium supplemented with 0.5 mg/L (±) ABA prior to cryopreservation. The embryos resumed growth within three days when returned to MS medium devoid of ABA but containing 2mg/L 2,4-dichlorophenoxyacetic acid. The embryogenic calli produced from these embryos exhibited normal plant regeneration on auxin-free media. Changes in dw/fw ratio, as well as the esterified fatty acid and sucrose concentrations correlated positively with the development of tolerance to cryopreservation.

17.
Plant Physiol ; 99(4): 1704-7, 1992 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-16669097

RESUMO

Somatic embryogenesis was induced in hypocotyl explants of geranium (Pelargonium x hortorum) cultured on media supplemented with various concentrations of N-phenyl-N'-1,2,3-thiadiazol-5-ylurea (thidiazuron). In less than 2 weeks, somatic embryos were observed in treatments containing levels of thidiazuron (TDZ) ranging from 0.2 to 1.0 micromolar. The use of N(6)-benzylaminopurine in combination with indole-3-acetic acid also evoked embryogenesis, but the efficiency of somatic embryo production was significantly lower than that obtained with TDZ. Hypocotyl culture for only 2 days on TDZ-supplemented medium before transfer to a basal medium was sufficient for inducing somatic embryogenesis. This distinction between the induction and expression of embryogenesis may provide an experimental system for studying the developmental biology of somatic embryogenesis. Substitution of the auxin-cytokinin requirement for the induction of somatic embryogenesis by TDZ suggests the possibility of a novel mode of its action by modulation of endogenous growth regulators.

18.
Plant Cell Rep ; 11(9): 443-8, 1992 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-24201586

RESUMO

Intact seedlings of hybrid seed geranium (Pelargonium x hortorum Bailey) were tested for their ability to produce adventitious shoots and somatic embryos by direct culture of mature seeds on Murashige and Skoog (1962) medium (MS) supplemented with growth regulators BAP, BAP + IAA, or thidiazuron (TDZ). Ten varieties were tested in the presence of different BAP concentrations, four with BAP + IAA, and two with TDZ. Varieties used in this study differed in their response to BAP in the medium. Multiple adventitious shoots were produced by seven of the ten varieties tested. Multiple adventitious shoots were induced at all levels of TDZ in the medium. TDZ also induced callusing from roots and direct embryogenesis from intact hypocotyls. Adventitious shoots were separated, rooted and transferred to soil where they grew as normal healthy plants and flowered.

19.
Plant Cell Rep ; 10(11): 587-9, 1991 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24221336

RESUMO

The effect of a non-indole compound, phenylacetic acid (PAA), on the induction of somatic embryogenesis in tissue cultures of geranium (Pelargonium x hortorum Bailey cv. Scarlet Orbit Improved) was investigated. Hypocotyl explants derived from young, dark-grown seedlings were cultured on Murashige and Skoog (1962) medium (MS) supplemented with PAA or IAA (0.01-120 µM) alone or in combination with BAP (8 µM). Somatic embryogenesis was induced by both PAA and IAA at 0.01-20 µM with 8 µM BAP, however, the optima differed considerably for the two compounds. Maximal activity of IAA for somatic embryogenesis was found at 0.1-2.5 µM, whereas PAA gave best results at 10 and 20 µM under identical culture conditions. Higher concentrations (30-120 µM) of IAA or PAA in the medium induced callusing in the explants, but the callus was neither embryogenic nor morphogenic.

20.
Plant Physiol ; 94(4): 1756-62, 1990 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-16667913

RESUMO

A cryoselection protocol has been developed that provides freezing-tolerant callus that, in turn, can regenerate plants with enhanced cold hardiness. Tolerant calli were selected from spring wheat (Triticum aestivum L.) callus by immersion in liquid nitrogen without addition of cryoprotectants. Less than 15% of the calli survived the initial challenge, whereas 30 to 40% of previously selected calli survived subsequent exposure. Seed progeny from five of 11 regenerant (R2) lines tested exhibited significantly enhanced tolerance to freezing at -12 degrees C. Thus, cryoselection appears to involve at least in part, selection for genetic rather than epigenetic variants. Analysis of one callus line indicated that cryoselection did not induce significant alterations in lipid composition, adenylate energy charge, or freezing point. An increase in the soluble sugar component was detected. Changes were also detected in the protein complement of microsomal membrane and soluble protein extracts of cryoselected callus. In all, seven unique proteins ranging from 79 to 149 kilodaltons were identified. The results demonstrate that freezing tolerant callus can be isolated from a heterogeneous population by cryoselection, and factors that contribute to hardiness at the callus level are biologically stable and can contribute to tolerance at the whole plant level.

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