Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 109
Filtrar
1.
Nanotechnology ; 35(16)2024 Jan 30.
Artículo en Inglés | MEDLINE | ID: mdl-38171320

RESUMEN

Carbon nanowalls (CNWs) have attracted significant attention for gas sensing applications due to their exceptional material properties such as large specific surface area, electric conductivity, nano- and/or micro-porous structure, and high charge carrier mobility. In this work, CNW films were synthesized and used to fabricate gas sensors for carbon dioxide (CO2) gas sensing. The CNW films were synthesized using an inductively-coupled plasma (ICP) plasma-enhanced chemical vapor deposition (PECVD) method and their structural and morphological properties were characterized using Raman spectroscopy and electron microscopy. The obtained CNW films were used to fabricate gas sensors employing interdigitated gold (Au) microelectrodes. The gas sensors were fabricated using both direct synthesis of CNW films on interdigitated Au microelectrodes on quartz and also transferring presynthesized CNW films onto interdigitated Au microelectrodes on glass. The CO2gas-sensing properties of fabricated devices were investigated for different concentrations of CO2gas and temperature-ranges. The sensitivities of fabricated devices were found to have a linear dependence on the concentration of CO2gas and increase with temperature. It was revealed that devices, in which CNW films have a maze-like structure, perform better compared to the ones that have a petal-like structure. A sensitivity value of 1.18% was obtained at 500 ppm CO2concentration and 100 °C device temperature. The CNW-based gas sensors have the potential for the development of easy-to-manufacture and efficient gas sensors for toxic gas monitoring.

2.
Heliyon ; 10(1): e23844, 2024 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-38192869

RESUMEN

The paper was devoted to the results of the study of methods to obtain superhydrophobic film based on the plasma polymerisation of hexamethyldisiloxane (HMDSO) inside the plasma jet at atmospheric pressure. The 3D printing technology was intended for film deposition, which has the advantage of producing superhydrophobic surfaces over a wide range of scales. The effect of synthesis parameters on the hydrophobic properties of the film has been studied. The obtained superhydrophobic films demonstrated stability and resistance in chemical solutions, at high temperatures, under the influence of UV-irradiation and in various weather conditions. The results can be used in various fields, including automotive, construction, electronics, medicine and others, where surface protection against moisture, contamination and corrosion is required.

3.
Isr Med Assoc J ; 24(9): 559-563, 2022 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-36168173

RESUMEN

BACKGROUND: To mitigate the spread of coronavirus disease 2019 (COVID-19), national guidelines, in accordance with international health authorities, mandated 14 days of quarantine for every close contact of a confirmed COVID-19 patient. Although health benefits are obvious, consequences are profound, especially for organizations required to maintain operational preparedness. OBJECTIVES: To present the Israel Defense Force (IDF) experience with outbreaks regarding quarantined individuals. To weigh the consequences of quarantined individuals needed for workforce and operation. METHODS: All positive COVID-19 cases in the IDF, as measured by a positive rRT-PCR test result, between 29 February and 18 May 2020 were evaluated. Numbers of positive individuals, quarantined individuals, and confirmatory exams conducted were collected. We compared the events in four units with the largest outbreaks and assessed the impact of confirmed cases, tests conducted, and workforce loss due to quarantine. RESULTS: Of the 187 soldiers who tested positive for COVID-19, source of infection was traced to 140 soldiers (75%). Almost no medical treatment was delivered, and hospitalization was rare. We found a median of 15.2% (interquartile range 5.3-34) for decline in unit workforce due to quarantine measures. Maximum reduction reached 47% of the workforce in one unit. CONCLUSIONS: Despite a relatively small number of confirmed cases, units underwent a substantial change in mode of operation due to the toll of quarantined individuals. In certain populations and organizations, perhaps a more liberal application of isolation and contact tracing is suitable due to the heavy economic burden and consequences in term of operational readiness.


Asunto(s)
COVID-19 , COVID-19/epidemiología , COVID-19/prevención & control , Brotes de Enfermedades/prevención & control , Humanos , Israel/epidemiología , Instalaciones Militares , SARS-CoV-2
4.
J Med Internet Res ; 23(9): e24295, 2021 09 10.
Artículo en Inglés | MEDLINE | ID: mdl-34313589

RESUMEN

BACKGROUND: The COVID-19 outbreak required prompt action by health authorities around the world in response to a novel threat. With enormous amounts of information originating in sources with uncertain degree of validation and accuracy, it is essential to provide executive-level decision-makers with the most actionable, pertinent, and updated data analysis to enable them to adapt their strategy swiftly and competently. OBJECTIVE: We report here the origination of a COVID-19 dedicated response in the Israel Defense Forces with the assembly of an operational Data Center for the Campaign against Coronavirus. METHODS: Spearheaded by directors with clinical, operational, and data analytics orientation, a multidisciplinary team utilized existing and newly developed platforms to collect and analyze large amounts of information on an individual level in the context of SARS-CoV-2 contraction and infection. RESULTS: Nearly 300,000 responses to daily questionnaires were recorded and were merged with other data sets to form a unified data lake. By using basic as well as advanced analytic tools ranging from simple aggregation and display of trends to data science application, we provided commanders and clinicians with access to trusted, accurate, and personalized information and tools that were designed to foster operational changes and mitigate the propagation of the pandemic. The developed tools aided in the in the identification of high-risk individuals for severe disease and resulted in a 30% decline in their attendance to their units. Moreover, the queue for laboratory examination for COVID-19 was optimized using a predictive model and resulted in a high true-positive rate of 20%, which is more than twice as high as the baseline rate (2.28%, 95% CI 1.63%-3.19%). CONCLUSIONS: In times of ambiguity and uncertainty, along with an unprecedented flux of information, health organizations may find multidisciplinary teams working to provide intelligence from diverse and rich data a key factor in providing executives relevant and actionable support for decision-making.


Asunto(s)
COVID-19 , Pandemias , Inteligencia Artificial , Toma de Decisiones , Humanos , SARS-CoV-2
5.
Acta Biomater ; 120: 116-123, 2021 01 15.
Artículo en Inglés | MEDLINE | ID: mdl-32711083

RESUMEN

Various material-strengthening strategies have evolved in the cuticle and the feeding tools of arthropods. Of particular interest is the crustacean mandible, which is frequently reinforced with calcium phosphate, giving a minerology similar to that of human bones and teeth. We report here a biological strengthening method of apatite by Zn substitution, found in the incisor teeth of the freshwater prawn Macrobrachium rosenbergii. Nanoindentation measurements show a clear positive correlation between the Zn/Ca ratio and the stiffness and hardness of the composite. In the incisor, Zn-substituted apatite forms an internal vertical axis, extending from the sharp outer edges of the tooth to its basal segment. The substitution level in this zone (up to 40%) is very high compared with the levels achieved in synthetic ceramics (<20%). Finite element simulation suggests that the high-Zn axis acts as a unique internal load transfer element, directing stress from the biting cusps to the more compliant underlying layers. In light of the considerable research being invested in developing synthetic calcium phosphate derivatives for human bone and tooth grafts, the innovative mineralogy of the M. rosenbergii incisor may inspire beneficial biomimetic applications. STATEMENT OF SIGNIFICANCE: The controlled incorporation of impurities into biominerals is a widespread phenomenon in biomineralization that may pave the way to new classes of biomimetic materials. The present study reveals a biogenic mineral of zinc-substituted apatite found in the incisor teeth of a prawn. A clear correlation between zinc substitution level and stiffness and hardness, suggests that zinc substitution serves to mechanically reinforce the bioapatite. The spatial arrangement of the high-zinc apatite unveils a material-level adaptation strategy for tooth fortification, in which the rigid high-Zn structure servs as an internal load-transfer element that transmits the stress directly from the tooth's sharp cusps to the more compliant underlying layers.


Asunto(s)
Materiales Biomiméticos , Diente , Ácidos , Apatitas , Humanos , Incisivo , Zinc
6.
Endocrinology ; 157(2): 928-41, 2016 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-26677879

RESUMEN

Sexual differentiation and maintenance of masculinity in crustaceans has been suggested as being regulated by a single androgenic gland (AG) insulin-like peptide (IAG). However, downstream elements involved in the signaling cascade remain unknown. Here we identified and characterized a gene encoding an insulin-like receptor in the prawn Macrobrachium rosenbergii (Mr-IR), the first such gene detected in a decapod crustacean. In mining for IRs and other insulin signaling-related genes, we constructed a comprehensive M. rosenbergii transcriptomic library from multiple sources. In parallel we sequenced the complete Mr-IR cDNA, confirmed in the wide transcriptomic library. Mr-IR expression was detected in most tissues in both males and females, including the AG and gonads. To study Mr-IR function, we performed long-term RNA interference (RNAi) silencing in young male prawns. Although having no effect on growth, Mr-IR silencing advanced the appearance of a male-specific secondary trait. The most noted effects of Mr-IR silencing were hypertrophy of the AG and the associated increased production of Mr-IAG, with an unusual abundance of immature sperm cells being seen in the distal sperm duct. A ligand blot assay using de novo recombinant Mr-IAG confirmed the existence of a ligand-receptor interaction. Whereas these results suggest a role for Mr-IR in the regulation of the AG, we did not see any sexual shift after silencing of Mr-IR, as occurred when the ligand-encoding Mr-IAG gene was silenced. This suggests that sexual differentiation in crustaceans involve more than a single Mr-IAG receptor, emphasizing the complexity of sexual differentiation and maintenance.


Asunto(s)
Hormonas Gonadales/metabolismo , Gónadas/metabolismo , Palaemonidae/genética , Proteínas Tirosina Quinasas Receptoras/genética , Receptor de Insulina/genética , Reproducción/genética , Diferenciación Sexual/genética , Animales , ADN Complementario , Femenino , Biblioteca de Genes , Masculino , Interferencia de ARN , Proteínas Tirosina Quinasas Receptoras/metabolismo , Receptor de Insulina/metabolismo
7.
Gen Comp Endocrinol ; 173(1): 4-10, 2011 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-21596044

RESUMEN

In malacostracan crustaceans, sex differentiation is uniquely regulated by a hormone secreted by the male-specific androgenic gland (AG). An isopod AG hormone was the first to be structurally elucidated and was found to belong to the insulin superfamily of proteins. Recently, it has been found that the AGs of several decapod crustaceans express insulin-like androgenic gland factors (IAGs), whose function is believed to be similar to that of the isopod AG hormone. Here we report the isolation from the blue crab Callinectes sapidus of the full-length cDNA encoding a candidate insulin-like AG hormone, termed Cas-IAG. The predicted protein Cas-IAG was encoded as a precursor consisting of a signal peptide, the B chain, the C peptide, and the A chain in that order. While the AG was the main source of Cas-IAG expression, as found in other decapod species, the hepatopancreas of male Callinectes sapidus crabs displayed minor Cas-IAG expression. Eyestalk ablation confirmed the presence of a possible endocrine axis between the eyestalk ganglia and the AG, implying that Cas-IAG expression is negatively regulated by (a) substance(s) present in the eyestalk ganglia.


Asunto(s)
Braquiuros/metabolismo , Glándulas Exocrinas/metabolismo , Hormonas de Invertebrados/metabolismo , Animales , Masculino
8.
Heredity (Edinb) ; 107(5): 456-61, 2011 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-21522169

RESUMEN

In this study, a female-specific DNA marker in the freshwater prawn Macrobrachium rosenbergii was identified through amplified fragment length polymorphism (AFLP). The AFLP-derived sequence-characterized amplified region (SCAR) marker was tested in over 200 individuals, giving reproducible sex identification. Further molecular characterization of the sex-marker's genomic region (∼ 3 kb long) revealed the presence of tandem and inverted repeats. The ∼ 3-kb sequence was identified both in male and female prawns, but with subtle differences: a deletion of 3 bp (present in female prawn but absent in male prawn) identified upstream of the SCAR marker sequence and two female-specific single-nucleotide polymorphisms, both indicating that male prawns are homozygous, whereas female prawns are heterozygous in this locus. Fluorescent in situ hybridization showed the ∼ 3-kb sequence to be unique: to the best of our knowledge, this is the first report of a unique sex-specific sequence observed in situ in crustaceans. The sex-specific marker identified in M. rosenbergii may have considerable applied merit for crustacean culture in that it will enable the determination of genetic sex at early developmental stages when phenotypic differences are not identifiable.


Asunto(s)
ADN/genética , Palaemonidae/genética , Cromosomas Sexuales , Análisis para Determinación del Sexo/métodos , Análisis del Polimorfismo de Longitud de Fragmentos Amplificados , Animales , Secuencia de Bases , ADN/aislamiento & purificación , Femenino , Marcadores Genéticos , Genoma , Genotipo , Heterocigoto , Hibridación Fluorescente in Situ , Masculino , Fenotipo , Análisis de Secuencia de ADN , Caracteres Sexuales
9.
Ann Burns Fire Disasters ; 24(4): 199-202, 2011 Dec 31.
Artículo en Inglés | MEDLINE | ID: mdl-22639563

RESUMEN

The treatment and hospitalization policies in various hospitals in Israel are influenced by injury severity and by the existence or non-existence of a designated burn treatment body. Severely injured burn victims requiring designated burn treatment are referred to one of Israel's five major burn units located in the highest level trauma centres that have an advanced burn treatment infrastructure. This national distribution of burn centres ensures designated treatment availability in various areas according to Israeli demographics, geography, and security threats. Israel does not have an obligatory burn report policy. Implementation of a national burn repository such as that in the USA will be able to give burn treatment specialists in our country a basis for comparison of treatment standards and allow for better care for burn victims. The Israeli Burn Association has a major role in the processes discussed in the manuscript.

10.
Insect Mol Biol ; 16(6): 661-74, 2007 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-18092996

RESUMEN

Alterations of hepatopancreatic multi-transcript expression patterns, related to induced moult cycle, were identified in male Cherax quadricarinatus through cDNA microarray hybridizations of hepatopancreatic transcript populations. Moult was induced by X-organ sinus gland extirpation or by repeated injections of 20-hydroxyecdysone. Manipulated males were sacrificed at premoult or early postmoult, and a reference population was sacrificed at intermoult. Differentially expressed genes among the four combinations of two induction methods and two moult stages were identified. Biologically interesting clusters revealing concurrently changing transcript expressions across treatments were selected, characterized by a general shift of expression throughout premoult and early postmoult vs. intermoult, or by different premoult vs. postmoult expressions. A number of genes were differentially expressed in 20-hydroxyecdysone-injected crayfish vs. X-organ sinus gland extirpated males.


Asunto(s)
Astacoidea/crecimiento & desarrollo , Astacoidea/genética , Animales , Astacoidea/efectos de los fármacos , Secuencia de Bases , Clonación Molecular , Cartilla de ADN/genética , Ecdisterona/farmacología , Perfilación de la Expresión Génica , Regulación del Desarrollo de la Expresión Génica , Hepatopáncreas/metabolismo , Masculino , Datos de Secuencia Molecular , Muda/efectos de los fármacos , Muda/genética , Análisis de Secuencia por Matrices de Oligonucleótidos
11.
Harefuah ; 145(6): 404-7, 472, 2006 Jun.
Artículo en Hebreo | MEDLINE | ID: mdl-16838892

RESUMEN

BACKGROUND: The risk of women who undergo surgery for the treatment of pelvic organ prolapse (POP) by the age of 80 is reported to exceed 10%, and is expected to rise with the increase in life expectancy. Most women affected are in their 5th or 6th decade, and the majority will suffer other medical problems. The current medical literature asserts that the vaginal surgical approach for POP operations are followed by less complications and provide a shorter rehabilitation period than the abdominal route. Hysterectomy is widely accepted as part of POP reconstructive surgery whenever the uterus is significantly prolapsed, however, there is no clear evidence to support the role of hysterectomy in improving surgery outcome. We present our experience with a new minimally invasive procedure - the posterior intravaginal slingplasty (IVS) for utero-suspension in the presence of moderate and advanced uterine prolapse. AIM: To evaluate the feasibility, intra- and post-operative complications and short term results of the posterior IVS procedure and uterosuspension for uterine prolapse. METHODS: Reconstructive surgery using the posterior IVS was performed on 18 women with moderate to severe uterine prolapse who chose to preserve their uterus. Patients were then followed 1,6,12 months and 2 years post-operatively to assess any recurrence of pelvic organ prolapse. RESULTS: No major intra- or post-operative complications were reported. Follow-up of one to 13 months showed good results. CONCLUSIONS: Reconstructive POP surgery may not necessitate hysterectomy. The posterior IVS is a novel safe, minimally invasive, simple and effective surgical procedure for the treatment of POP, permitting uterine preservation. A larger number of patients and a longer follow-up period are required for proper evaluation of the actual safety and efficacy of this procedure.


Asunto(s)
Prolapso Uterino/cirugía , Femenino , Procedimientos Quirúrgicos Ginecológicos , Humanos , Procedimientos Quirúrgicos Mínimamente Invasivos , Procedimientos de Cirugía Plástica , Resultado del Tratamiento
12.
Genet Res ; 82(2): 107-16, 2003 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-14768895

RESUMEN

In the Australian red-claw crayfish Cherax quadricarinatus (von Martens) (Decapoda, Parastacidae), a gonochoristic species, seven different combinations of intersex individuals (with both male and female genital openings) have been described. However, to date, the genetic basis for this phenomenon has not been investigated. This study was designed to test a simple chromosome-based sex-determination model for C. quadricarinatus that assumes the male to be the homogametic (ZZ) sex. According to our model, intersex individuals that are functionally males are genetically females (WZ). Individual crosses were performed between intersex and female crayfish, with control crosses being performed between normal males and females. The control crosses yielded, in most cases, the expected 1:1 sex ratio in the F1 progeny. Crosses between intersex individuals and females yielded a 1:3 (male:female) sex ratio in most crosses. According to our hypothesis, one-third of the females produced in a cross of a female with an intersex animal should be WW females. The hypothesis was tested by crossing normal males with F1 females, which were progeny of intersex fathers. These crosses yielded almost 100% females, a finding that conforms to the above-suggested sex determination model for C. quadricarinatus and the female WZ genotype of intersex individuals.


Asunto(s)
Astacoidea/genética , Procesos de Determinación del Sexo , Animales , Cruzamientos Genéticos , Trastornos del Desarrollo Sexual/genética , Femenino , Genotipo , Masculino , Modelos Genéticos , Caracteres Sexuales , Razón de Masculinidad
13.
Burns ; 27(7): 781-2, 2001 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-11600262

RESUMEN

A patient with a second-degree burn of the forehead, induced by topical application of crushed garlic is reported. The literature on garlic burns is reviewed.


Asunto(s)
Quemaduras Químicas/etiología , Frente/lesiones , Ajo/efectos adversos , Asma/tratamiento farmacológico , Ajo/historia , Historia del Siglo XX , Historia Antigua , Humanos , Masculino , Persona de Mediana Edad
15.
J Exp Zool ; 290(3): 218-26, 2001 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-11479901

RESUMEN

The yolk protein of Cherax quadricarinatus contains six major high-density lipoprotein (HDL) subunits with the approximate molecular masses of 177, 155, 106, 95, 86, and 75 kDa, of which only the 106-kDa polypeptide is negatively charged. On the basis of their molecular weights, time of appearance and disappearance, their floating density and susceptibility to enzyme degradation (by a serine proteinase), these six HDL polypeptides were classified into two subgroups. One group comprises the higher-molecular-weight compounds above 106 kDa, and the other includes the lower-molecular-weight compounds up to 95 kDa. Other than being different from the lower-molecular-weight polypeptides, the negatively charged 106-kDa polypeptide was significantly different from members of its higher-molecular-weight group belonging to a different, less abundant, yolk protein as shown by HPLC separation. Immunological studies and peptide mapping in which the 106-kDa polypeptide did not show similarity to any of the other HDL components confirmed these differences. Moreover, the amino acid composition of the 106-kDa polypeptide was different from that of known vitellin from other crustacean species. This unique negatively charged polypeptide presents an enigma as it is known to be a secondary vitellogenic-related HDL polypeptide, immunolocalized in yolk globules; however, it is different to all the other HDL polypeptides, thus presenting the question whether it is indeed a component of "classical" crustacean vitellin.


Asunto(s)
Astacoidea/química , Crustáceos/química , Proteínas del Huevo/química , Lipoproteínas HDL/química , Animales , Cromatografía Líquida de Alta Presión , Femenino , Mapeo Peptídico , Péptidos/química
16.
Gen Comp Endocrinol ; 121(3): 242-9, 2001 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-11254366

RESUMEN

The role of the androgenic gland (AG), an organ unique to male Crustacea, in the development of sex characters and physiology of the reproductive system has not been fully documented in the red claw crayfish, Cherax quadricarinatus. To investigate the role of the AG in this species, the effect of implanting hypertrophied AGs into immature female animals was followed. Of the female animals with AG implants, 91.6% developed male-like propodi, including the red patch characteristic of males of this species. The development of female secondary sex characteristics such as a wider abdomen, a wider endopod, and simple setation was inhibited. At the end of the experiment, the ovaries of the AG-implanted females contained mostly lipid-stage oocytes, with a small number of oocytes at the early yolk stage. The gonadosomatic index of the AG-implanted females was significantly lower than that of the control (sperm duct-implanted or sham-operated) females, which had mature oocytes with a well-defined perinuclear zone and yolk globules. An immunohistochemical test using an antibody developed against a 106-kDa secondary vitellogenic polypeptide showed only slight immunoreactivity in the oocytes of AG-implanted females compared with abundant immunoreactivity in control ovaries. In the polypeptide profile of the high-density lipoprotein (HDL) from the hemolymph of AG-implanted females, the 206- and 79-kDa secondary vitellogenesis-specific polypeptides were not found, whereas they were present in the profile of control females. In contrast, the female-specific 177-kDa polypeptide was present in the polypeptide profile of hemolymph HDL of both AG-implanted females and control females. It seems therefore that while secondary sex characters were masculinized under the influence of the implanted AG, the process of vitellogenesis was suppressed but not fully eliminated in the AG-implanted females.


Asunto(s)
Andrógenos/metabolismo , Astacoidea/fisiología , Glándulas Endocrinas/trasplante , Caracteres Sexuales , Animales , Astacoidea/anatomía & histología , Electroforesis en Gel de Poliacrilamida , Glándulas Endocrinas/fisiología , Femenino , Hemolinfa/química , Hipertrofia , Inmunohistoquímica , Masculino , Oocitos/citología , Ovario/anatomía & histología , Péptidos/sangre , Reproducción
17.
Pediatrics ; 107(2): E22, 2001 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-11158496

RESUMEN

Epulis is a rare tumor of the newborn, also known as granular cell tumor of the newborn or Neumann's tumor. This tumor arises from the mucosa of the gingiva, most commonly from the anterior part of the maxillary alveolar ridge, and is typically seen as a mass protruding out of the newborn child's mouth, which may interfere with respiration or feeding. Epulis is seen only in the newborn and is a different entity from other granular cell tumors. The tumor has a marked female preponderance of 8:1. The recommended treatment is prompt surgical resection. Recurrences of the tumor and damage to future dentition have not been reported, suggesting that radical excision is not warranted. A newborn female with such a mass is described. The tumor was resected using a carbon dioxide laser; the postoperative course was uneventful. On histologic examination, it was composed of diffuse sheets and clusters of polygonal cells containing small round to oval nuclei and abundant coarsely granular cytoplasm. The tumor cells stained positive for vimentin, and negative for S100-protein, actin, desmin, laminin, keratin, estrogen, and progesterone receptors. Electron microscopic examination showed granular cells containing heterogeneous electron-dense granules, lysosomes, and cytoplasmic lipid droplets. The clinical and microscopic features of such tumors are reviewed.


Asunto(s)
Neoplasias Gingivales/congénito , Tumor de Células Granulares/congénito , Femenino , Neoplasias Gingivales/patología , Neoplasias Gingivales/cirugía , Tumor de Células Granulares/patología , Tumor de Células Granulares/cirugía , Humanos , Recién Nacido , Terapia por Láser , Microscopía Electrónica
18.
Comp Biochem Physiol B Biochem Mol Biol ; 127(3): 411-21, 2000 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-11126772

RESUMEN

The high-density lipoproteins LPI and LPII were isolated from the hemolymph of the crayfish Cherax quadricarinatus by gradient ultracentrifugation and high-performance liquid chromatography (HPLC). Both lipoproteins contained a carotenoid moiety. LPI is comprised of a single polypeptide with an approximate molecular mass of 96 kDa. LPII was composed of two similar native components, LPIIa and LPIIb, both having polypeptides of 80 and 177 kDa. Both under natural conditions and after endocrine manipulations, LPI was present in males and in females, regardless of the female reproductive stage. LPII was present only in secondary-vitellogenic females, but not during the winter reproductive arrest period. LPII was also absent from young females that had received androgenic gland implants. LPII also appeared in the hemolymph of intersex individuals from which the androgenic gland had been removed. It is therefore suggested that LPII serves as a marker indicating the onset of secondary vitellogenesis in C. quad'iariicarintus females.


Asunto(s)
Astacoidea/metabolismo , Lipoproteínas HDL/metabolismo , Vitelogénesis/fisiología , Animales , Astacoidea/fisiología , Femenino , Hemolinfa/metabolismo , Lipoproteínas HDL/clasificación , Lipoproteínas HDL/aislamiento & purificación , Masculino
20.
Gen Comp Endocrinol ; 118(2): 200-8, 2000 May.
Artículo en Inglés | MEDLINE | ID: mdl-10890562

RESUMEN

During ovarian maturation in the crayfish Cherax quadricarinatus, changes in ovarian protein kinase C (PKC) isoenzymes take place in parallel to yolk accumulation (as shown by immunoblot analysis). Significant changes were recorded in the amounts of specific isoenzymes and in their distribution between the cytosol and the membranes. Ovarian maturation was accompanied by the appearance of high- and low-molecular-weight immunoreactive PKC isoenzyme species. Among the isoenzymes tested, PKC alpha was the most clearly activated during ovarian maturation, as shown by significant translocation from the cytosol to the particulate fraction and the appearance of high-molecular-weight species. Moreover, a similar picture was obtained in the ovaries of intersex individuals upon induction of secondary vitellogenesis by androgenic gland ablation. Immunohistological staining showed PKC alpha to be localized mainly in the cytosol of premature oocytes, whereas in later maturation stages, it was concentrated around the nucleus in a vesicular structure and in the oocyte membrane. In secondary vitellogenic stages, PKC was localized in the plasma membrane and apparently in follicular cells. In addition, its activity was demonstrated by in vitro phosphorylation assays of a crayfish ovarian homogenate. Activation of total PKC phosphorylation of histone, an external substrate, was induced by phosphatidylserine plus 12-O-tetradecanoylphorbol-13-acetate (TPA) or methyl farnesoate. Both TPA and methyl farnesoate stimulated activation of PKC alpha in organ culture, causing its translocation from the cytosol to the membranes and inducing autophosphorylation of threonine residues. The changes in PKC isoenzymes during ovarian maturation in the crayfish suggest their involvement in this process as well as a possible regulatory role for methyl farnesoate through a direct effect on some PKC isoenzymes.


Asunto(s)
Astacoidea/fisiología , Ácidos Grasos Insaturados/farmacología , Isoenzimas/metabolismo , Proteína Quinasa C/metabolismo , Vitelogénesis , Animales , Activación Enzimática/efectos de los fármacos , Femenino , Oocitos/enzimología , Técnicas de Cultivo de Órganos , Ovario/enzimología , Ovario/fisiología , Acetato de Tetradecanoilforbol/farmacología , Distribución Tisular
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA