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1.
Cell ; 168(1-2): 264-279.e15, 2017 01 12.
Artículo en Inglés | MEDLINE | ID: mdl-28086093

RESUMEN

The life cycle of a primary cilium begins in quiescence and ends prior to mitosis. In quiescent cells, the primary cilium insulates itself from contiguous dynamic membrane processes on the cell surface to function as a stable signaling apparatus. Here, we demonstrate that basal restriction of ciliary structure dynamics is established by the cilia-enriched phosphoinositide 5-phosphatase, Inpp5e. Growth induction displaces ciliary Inpp5e and accumulates phosphatidylinositol 4,5-bisphosphate in distal cilia. This change triggers otherwise-forbidden actin polymerization in primary cilia, which excises cilia tips in a process we call cilia decapitation. While cilia disassembly is traditionally thought to occur solely through resorption, we show that an acute loss of IFT-B through cilia decapitation precedes resorption. Finally, we propose that cilia decapitation induces mitogenic signaling and constitutes a molecular link between the cilia life cycle and cell-division cycle. This newly defined ciliary mechanism may find significance in cell proliferation control during normal development and cancer.


Asunto(s)
Ciclo Celular , Cilios/metabolismo , Actinas/metabolismo , Animales , Riñón/citología , Riñón/metabolismo , Ratones , Células 3T3 NIH , Fosfatidilinositol 4,5-Difosfato , Monoéster Fosfórico Hidrolasas/metabolismo , Proteína con Dedos de Zinc GLI1/metabolismo
2.
J Cell Sci ; 135(19)2022 10 01.
Artículo en Inglés | MEDLINE | ID: mdl-36222105

RESUMEN

Cilia sense and transduce sensory stimuli, homeostatic cues and developmental signals by orchestrating signaling reactions. Extracellular vesicles (EVs) that bud from the ciliary membrane have well-studied roles in the disposal of excess ciliary material, most dramatically exemplified by the shedding of micrometer-sized blocks by photoreceptors. Shedding of EVs by cilia also affords cells with a powerful means to shorten cilia. Finally, cilium-derived EVs may enable cell-cell communication in a variety of organisms, ranging from single-cell parasites and algae to nematodes and vertebrates. Mechanistic understanding of EV shedding by cilia is an active area of study, and future progress may open the door to testing the function of ciliary EV shedding in physiological contexts. In this Cell Science at a Glance and the accompanying poster, we discuss the molecular mechanisms that drive the shedding of ciliary material into the extracellular space, the consequences of shedding for the donor cell and the possible roles that ciliary EVs may have in cell non-autonomous contexts.


Asunto(s)
Cilios , Vesículas Extracelulares , Animales , Comunicación Celular , Cilios/fisiología , Vesículas Citoplasmáticas , Transducción de Señal
3.
Am J Bioeth ; : 1-12, 2024 Jul 17.
Artículo en Inglés | MEDLINE | ID: mdl-39018166

RESUMEN

Much of the debate over the definition and criteria for determining our death has focused on disagreement over the correct biological account of death, i.e., what it means for any organism to die. In this paper, we argue that this exclusive focus on the biology of death is misguided, because it ignores ethical and social factors that bear on the acceptability of criteria for determining our death. We propose that attention shift from strictly biological considerations to ethical and social considerations that bear on the determination of what we call "civil death." We argue for acceptance of a neurological criterion for determining death on grounds that it is the most reasonable way to synthesize biological, ethical, and social considerations about our death..

4.
Artículo en Inglés | MEDLINE | ID: mdl-38760630

RESUMEN

Suicide by ligature strangulation/hanging inside vehicles is uncommon, and only few cases have been reported in the literature. This study aimed to conduct a comprehensive review of reported cases of suicide by ligature strangulation/hanging inside vehicles, analyzing the features of the death scene, of the ligature and furrow, autopsy findings, and causes of death. The comprehensive review was performed following the PRISMA guidelines by using the most common scientific databases. According to inclusion criteria, a total of 20 cases of vehicle-assisted strangulation/hanging were reviewed: 13 cases were assessed as ligature strangulation resulting in 7 complete decapitations and 7 other cases as hanging. All victims were young or adult males, except for one 48-year-old female. Death was assessed as suicide in all cases, except for a possible accidental autoerotic death. In 8 cases, a history of depression or other psychiatric disorders was reported. Toxicological analysis were positive in 7 cases. Hard ligature materials (nylon, steel, plastic, hemp ropes) were used in most cases, but only 13 cases had a well-demarcated furrow. In 2 cases, no internal findings of asphyxia were found. An additional case of ligature strangulation inside a motor vehicle off is also presented, where no autopsy findings of asphyxia were observed, except for a broad pale furrow and monolateral conjunctival petechiae. This study highlights the challenges in classifying suicidal hanging and ligature strangulation in motor vehicles.

5.
Artículo en Inglés | MEDLINE | ID: mdl-38112975

RESUMEN

Suicide by vehicle-assisted strangulation resulting in decapitation is a rare occurrence, characterized by a high kinetic energy mechanism that produces a clean-cut appearance in the decapitation area. Often resembling an incisive wound, this particular finding can mislead local authorities into investigating the case as a homicide. This case report describes an adult male who accelerated his vehicle after tying a nylon rope around his neck and securing it to a metallic structure on the wall. Furthermore, we conducted a brief review of cases published within the last ten years, summarizing the most prevalent findings associated with these incidents. By analyzing previously reported cases alongside our own, we aim to consolidate the prevailing patterns observed in vehicle-assisted strangulation cases. This underscores the paramount importance of thorough scene analysis by the medico-legal team and emphasizes the significance of subsequent necropsy findings in accurately discerning the manner of death.

6.
J Exp Bot ; 73(7): 1963-1977, 2022 04 05.
Artículo en Inglés | MEDLINE | ID: mdl-34894212

RESUMEN

Tiller formation is a key agronomic determinant for grain yield in cereal crops. The modulation of this trait is controlled by transcriptional regulators and plant hormones, tightly regulated by external environmental conditions. While endogenous (genetic) and exogenous (environmental factors) triggers for tiller formation have mostly been investigated separately, it has remained elusive how they are integrated into the developmental program of this trait. The transcription factor gene INTERMEDIUM-C (INT-C), which is the barley ortholog of the maize domestication gene TEOSINTE BRANCHED1 (TB1), has a prominent role in regulating tiller bud outgrowth. Here we show that INT-C is expressed in tiller buds, required for bud growth arrest in response to shade. In contrast to wild-type plants, int-c mutant plants are impaired in their shade response and do not stop tiller production after shading. Gene expression levels of INT-C are up-regulated under light-limiting growth conditions, and down-regulated after decapitation. Transcriptome analysis of wild-type and int-c buds under control and shading conditions identified target genes of INT-C that belong to auxin and gibberellin biosynthesis and signaling pathways. Our study identifies INT-C as an integrator of the shade response into tiller formation, which is prerequisite for implementing shading responses in the breeding of cereal crops.


Asunto(s)
Regulación de la Expresión Génica de las Plantas , Hordeum , Genes de Plantas , Hordeum/genética , Hordeum/metabolismo , Fitomejoramiento , Reguladores del Crecimiento de las Plantas , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo
7.
J Exp Biol ; 225(17)2022 09 01.
Artículo en Inglés | MEDLINE | ID: mdl-35924486

RESUMEN

Certain animal species utilize electric fields for communication, hunting and spatial orientation. Freshwater planarians move toward the cathode in a static electric field (cathodic electrotaxis). This planarian behavior was first described by Raymond Pearl more than a century ago. However, planarian electrotaxis has received little attention since, and the underlying mechanisms and evolutionary significance remain unknown. To close this knowledge gap, we developed an apparatus and scoring metrics for automated quantitative and mechanistic studies of planarian behavior upon exposure to a static electric field. Using this automated setup, we characterized electrotaxis in the planarian Dugesia japonica and found that this species responds to voltage instead of current, in contrast to results from previous studies using other planarian species. Surprisingly, we found differences in electrotaxis ability between small (shorter) and large (longer) planarians. To determine the cause of these differences, we took advantage of the regenerative abilities of planarians and compared electrotaxis in head, tail and trunk fragments of various lengths. We found that tail and trunk fragments electrotaxed, whereas head fragments did not, regardless of size. Based on these data, we hypothesized that signals from the head may interfere with electrotaxis when the head area/body area reached a critical threshold. In support of this hypothesis, we found that (1) smaller intact planarians that cannot electrotax have a relatively larger head-to-body-ratio than large planarians that can electrotax, and (2) the electrotaxis behavior of cut head fragments was negatively correlated with the head-to-body ratio of the fragments. Moreover, we could restore cathodic electrotaxis in head fragments via decapitation, directly demonstrating inhibition of electrotaxis by the head.


Asunto(s)
Planarias , Animales , Evolución Biológica , Planarias/fisiología
8.
Int J Legal Med ; 135(1): 301-305, 2021 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-32474665

RESUMEN

We report a suicide case of complete decapitation using a self-constructed guillotine. A 45-year-old man, whose body was severely burned, was found dead. The head was completely separated from the middle level of the neck, and a sharp blade with a steel frame was placed between the head and neck. The severance plane passed between the C4 and C5 vertebrae. Vital reactions such as hemorrhage could not be confirmed at the decapitated skin edge because the body was severely burned. Both common carotid arteries were sharply transected. Subendocardial hemorrhage was detected in the left ventricle. Only a little blood, but no soot, was detected in the respiratory tract, including the trachea and bilateral bronchi. Subarachnoid hemorrhage was noted at the edge of the cervical spinal cord. The saturation level of CO-Hb was 5.7% in the left cardiac blood, 5.9% in the right cardiac blood, and 5.8% in the peripheral blood from the femoral vein. Cervical transection was diagnosed as the cause of death. We believe that he was unintentionally burned by spread fire from an automobile after decapitation by a self-constructed guillotine.


Asunto(s)
Quemaduras/patología , Decapitación , Suicidio Completo , Carboxihemoglobina/análisis , Traumatismos de las Arterias Carótidas/patología , Incendios , Ventrículos Cardíacos/patología , Hemorragia/patología , Humanos , Masculino , Persona de Mediana Edad , Sistema Respiratorio/patología , Hemorragia Subaracnoidea/patología
9.
Am J Phys Anthropol ; 174(1): 3-19, 2021 01.
Artículo en Inglés | MEDLINE | ID: mdl-32935864

RESUMEN

OBJECTIVES: Warfare is assumed to be one of the defining cultural characteristics of steppe nomads in Eastern Eurasia. For the first-centuries CE, a period of political turmoil in Northern China and Southern Siberia, relatively few data are, however, available about the degree and variability of violence in these communities. Here, we provide new data on violence among steppe nomads during the first-centuries CE by analyzing the type, anatomical distribution, and demographic distribution of perimortem trauma at Tunnug1 (Tuva, Southern Siberia-second to fourth c. CE). MATERIALS AND METHODS: Perimortem traumas were assessed on 87 individuals representing both sexes and different age classes. The timing of the lesions was assessed based on morphological criteria, including the absence and presence of bone reactive processes and the relative plasticity of the bone at the moment of impact. The distribution by age, sex, and anatomical location of trauma was analyzed by means of logistic models, Fisher's exact tests, and 3D visualizations. RESULTS: A total of 130 perimortem traumas, including chop marks, slice marks, penetrating lesions, and blunt traumas were identified on 22 individuals. Chop marks were mostly at the level of the skull and vertebrae and were likely caused by bladed weapons. Slice marks were found on the cervical vertebrae and cranium and may be the result of throat slitting and scalping by means of smaller bladed implements. Traumas were more frequent in males, and their presence is not correlated with age. DISCUSSION: This study adds new data to the few available regarding violence among steppe nomadic cultures and provides new insights about the effects of political instability on the life of the people inhabiting Eastern Eurasia during the early centuries CE.


Asunto(s)
Pueblo Asiatico/historia , Violencia/historia , Heridas Penetrantes/historia , Adolescente , Adulto , Antropología Física , Huesos/lesiones , Huesos/patología , Entierro/historia , Niño , Preescolar , Decapitación/historia , Femenino , Historia Antigua , Humanos , Lactante , Recién Nacido , Masculino , Siberia , Migrantes , Guerra/historia , Adulto Joven
10.
Ecotoxicol Environ Saf ; 215: 112162, 2021 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-33756287

RESUMEN

Decapitation and root cutting can influence plant physiological features, such as height, dry weight, and transpiration rate, which partly determine the success of phytoremediation. In this study, the effects of three root cutting intensities (10%, 25%, and 33%), decapitation, and their combination on the phytoremediation efficiency of Celosia argentea were evaluated. Decapitation increased the biomass yield of C. argentea roots and leaves and significantly improved the species' Cd decontamination ability. Root cutting, especially 33% cutting treatment, decreased the root dry weight. The 10% and 25% root cutting treatments increased the leaf biomass yield by 58.6% and 41.4%, respectively, compared with the untreated control, even compensating for the loss of roots, but 33% root cutting decreased the leaf dry weight. Low and moderate root cutting intensity (10% and 25%) increased the leaf Cd content by 33.4% and 24.9%, respectively, and was associated with improved transpiration rate. The highest root and leaf dry weights were observed for the combination of decapitation and 10% root cutting, which increased the biomass yield of underground and aerial parts by 109.9% and 286.2%, respectively. In addition, decapitation offset the negative effects of 33% root cutting on plant growth, indicated by the higher dry weight relative to the control. Decapitated C. argentea accumulated 11.0, 7.5, and 0.7 times more Cd with the 10%, 25%, and 33% root cutting treatments, respectively, compared with the control. The combination of root cutting and decapitation was a practicable and economical method of enhancing the Cd decontamination capacity of C. argentea.


Asunto(s)
Biodegradación Ambiental , Celosia , Contaminantes del Suelo/análisis , Biomasa , Decapitación , Raíces de Plantas/química , Plantas , Suelo
11.
Int J Mol Sci ; 22(18)2021 Sep 08.
Artículo en Inglés | MEDLINE | ID: mdl-34575868

RESUMEN

Temperature is an important factor that largely affects the patterns of shoot branching in plants. However, the effect and mechanism of temperature on axillary bud development in chrysanthemum remains poorly defined. The purpose of the present study is to investigate the effect of high temperature on the axillary bud growth and the mechanism of axillary bud formation in chrysanthemum. Decapitation experiments combined with the transcriptome analysis were designed. Results showed that the axillary bud length was significantly inhibited by high temperature. Decapitation of primary shoot (primary decapitation) resulted in slower growth of axillary buds (secondary buds) under 35 °C. However, secondary decapitation resulted in complete arrest of tertiary buds at high temperature. These results demonstrated that high temperature not only inhibited axillary bud formation but also retarded bud outgrowth in chrysanthemum. Comparative transcriptome suggested differentially expressed gene sets and identified important modules associated with bud formation. This research helped to elucidate the regulatory mechanism of high temperature on axillary bud growth, especially bud formation in chrysanthemum. Meanwhile, in-depth studies of this imperative temperature signaling can offer the likelihood of vital future applications in chrysanthemum breeding and branching control.


Asunto(s)
Chrysanthemum/embriología , Chrysanthemum/genética , Chrysanthemum/metabolismo , Regulación de la Expresión Génica de las Plantas , Fitomejoramiento , Reguladores del Crecimiento de las Plantas/genética , Citocininas/genética , Perfilación de la Expresión Génica , Genes de Plantas , Homeostasis , Calor , Ácidos Indolacéticos , Proteínas de Plantas/genética , Brotes de la Planta/genética , RNA-Seq , Sacarosa/química , Transcriptoma
12.
Forensic Sci Med Pathol ; 17(4): 730-733, 2021 12.
Artículo en Inglés | MEDLINE | ID: mdl-34106423

RESUMEN

Suicide by decapitation as a primary method of injury is not common. When decapitation does occur in association with suicide, it may be a secondary consequence of the primary method of suicide, for example massive blunt force trauma, or hanging with a significant drop; however, primary suicidal decapitation has been described specifically in the context of railway incidents wherein victims lie across railroad tracks in-front of oncoming trains. Herein we report the case of a 49-year-old male who was decapitated after lying-down with his neck atop a railroad track in a railroad stockyard. He was subsequently run over by a train as it began to move to leave the stockyard. This case of train-assisted suicide occurs less often than the more common modality of suicide by train wherein victims stand or jump in front of a moving train or lay their body across the railroad tracks in order to be struck by an oncoming train.


Asunto(s)
Decapitación , Vías Férreas , Humanos , Masculino , Persona de Mediana Edad , Cuello , Ideación Suicida
13.
Acta Neurochir (Wien) ; 162(10): 2537-2540, 2020 10.
Artículo en Inglés | MEDLINE | ID: mdl-32474639

RESUMEN

Chainsaw accidents are severe injuries, mostly work-related and concerning upper or lower extremities. Few suicidal chainsaw injuries are reported, all of them fatal. We report the case of a 23-year-old man who attempted suicide by sub-decapitation with a chainsaw, its successful (peri-) operative management, and clinical course along with a discussion of the contemporary management and body of evidence of such lesions. Chainsaw injuries are severe traumas. Stepwise surgery with maximal functional reconstruction is safe and optimal clinical outcome can be achieved.


Asunto(s)
Decapitación/cirugía , Procedimientos Neuroquirúrgicos/métodos , Traumatismos de la Médula Espinal/cirugía , Suicidio , Vértebras Cervicales/lesiones , Decapitación/etiología , Humanos , Masculino , Traumatismos de la Médula Espinal/etiología , Adulto Joven
14.
Plant Dis ; 104(1): 239-245, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31710571

RESUMEN

Citrus variegated chlorosis (CVC) disease, caused by the xylem-limited and insect-transmitted bacterium Xylella fastidiosa, has caused severe losses in orange production in Brazil. Disease control requires insecticide applications, tree removal, and pruning of symptomatic branches. Pruning success has been erratic, especially in areas of high disease incidence. In this work, in planta X. fastidiosa distribution and the effectiveness of severe pruning procedures for curing diseased adult trees were investigated. Most sampled upper parts of the trees contained X. fastidiosa, but at higher frequencies in symptomatic branches. Removal of all main branches (decapitation) was not effective and revealed a 20 to 30% incidence of latent infections. Trunk decapitation resulted in a higher number of healthy scions but killed 10 to 30% of the remaining trunks. Removal of all scion and grafting the newly sprouted shoots of 'Rangpur' lime (Citrus limonia Osbeck) or 'Cleopatra' (Citrus reshni Hort. ex Tan.) rootstocks with healthy buds allowed production of fast-growing and productive new scions that remained free from CVC for at least 2 years in four locations. With this method, highly affected trees do not need to be fully removed and the costs involved in this practice and in young tree acquisition and plantings are circumvented; therefore, it is a feasible option for less technically inclined small growers in Brazil.


Asunto(s)
Citrus sinensis , Citrus , Enfermedades de las Plantas , Xylella , Brasil , Citrus/microbiología , Enfermedades de las Plantas/prevención & control , Xylella/fisiología
15.
Forensic Sci Med Pathol ; 16(2): 325-329, 2020 06.
Artículo en Inglés | MEDLINE | ID: mdl-32166704

RESUMEN

Complete decapitation as a result of a suicidal hanging is rarely observed in forensic practice. The authors report a case of a 38-year-old man hanging from a bridge with a 4.2 m nylon rope. The man, weighing 70 kg, was wearing a 6.5 kg rucksack. The headless body was found lying in the river below the bridge and his head was found the next day in the river 6 m away from the bridge. Autopsy findings recorded a regular and concentric skin abrasion pattern and cervical spine transection between C2 and C3. Radiologic study depicted C2-C3 neck transection and the fracture of the left lamina and the spinous process of the axis. The force applied to the neck and the kinetic energy were calculated.


Asunto(s)
Decapitación/patología , Suicidio Completo , Adulto , Vértebras Cervicales/diagnóstico por imagen , Vértebras Cervicales/patología , Humanos , Masculino , Tomografía Computarizada por Rayos X
16.
Forensic Sci Med Pathol ; 15(4): 607-611, 2019 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-31471866

RESUMEN

Decapitation is well-documented as an immediately lethal injury that is encountered in medicolegal autopsies. It can be due to an accident, suicide, or homicide. Literature on decapitation reveals that suicide is committed by decapitation using domestic or industrial tools, such as electric saws and drills, and improvised guillotines. Decapitation can also be the result of railway or other bizarre incidents. In this particular case, a man committed suicide by decapitation using a log splitter. This has not been reported earlier. Death investigation, including a medicolegal autopsy and scene visit, was conducted. The decedent, a man in his late forties, had been diagnosed with bipolar disorder approximately five years prior to his death and was being treated for this condition. During the year prior to his death, he had been seeing his physician every two weeks for suicidal ideation. Scene investigation revealed a decapitated male lying beside a jigged and powered log splitter in his yard. The autopsy showed no other injuries or pathological conditions. The cause of death was decapitation and the manner of death was suicide. This is a unique case of decapitation by a log splitter which highlights the importance of scene investigation in order to determine the manner of death.


Asunto(s)
Decapitación , Suicidio Completo , Trastorno Bipolar/psicología , Humanos , Masculino , Persona de Mediana Edad , Ideación Suicida
17.
Forensic Sci Med Pathol ; 14(1): 117-119, 2018 03.
Artículo en Inglés | MEDLINE | ID: mdl-29181747

RESUMEN

Decapitation is an occurrence only rarely encountered in forensic medical practice. This fatality is generally most often described in pedestrians who have been run over by trains accidently or in cases of suicide, or alternatively in occupants of cars involved in high speed vehicle collisions. We report, for the first time, a case of a complete decapitation of a pedestrian as a consequence of a traffic accident. Due to a thorough medico-legal investigation of the body and the involved vehicle, we were able to reconstruct the unique dynamics of the accident and the mechanism of injury.


Asunto(s)
Accidentes de Tránsito , Decapitación , Peatones , Adulto , Humanos , Masculino , Persona de Mediana Edad , Traumatismo Múltiple/patología
18.
Microb Pathog ; 105: 13-18, 2017 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-28161359

RESUMEN

OBJECTIVE: Establishment of a male BALB/c mouse model to study the role of sperm impairing S. marcescens on mouse reproductive potential. The current study can add to use of reliable animal models to provide a noteworthy evidence for the microbial cause of infertility. METHODS: The mice in the test groups II, III, IV were intraperitoneally administered with different doses (104, 106 or 108 cfu) of S. marcescens whereas, group I serving as control, received PBS, for 10 consecutive days. The groups were evaluated for any change in body weight, tissue somatic index (%), seminal parameters and histology. Confirmation of S. marcescens from reproductive organs was done by reisolating the same by cultural characteristics and biochemical tests. RESULTS: The results showed that weight gain was evident only in mice receiving PBS (group I), whereas a decrease was recorded in the test groups (group II, III and IV). Only testes of test groups showed significant changes in TSI values whereas, no change in TSI was observed in any reproductive organ of any test group. Seminal parameters viz. sperm count, motility and viability were found to decrease in test groups II, III and IV as compared to control group I. Interestingly, the number of pus cells and percent decapitation was more prominent in test groups which received higher doses (i.e. group III and group IV). The histopathological examination revealed mild to dense inflammation in vas deferens and caudal epididymis in all test groups except hypospermatogenesis which was observed only in test group III and IV. However, in group I, neither adverse changes nor any sign of inflammation were observed. CONCLUSION: Intraperitoneal inoculation of S. marcescens could lead to alteration of semen parameters, induction of decapitation in spermatozoa and histopathological changes, thereby decreasing the reproductive potential of male mice.


Asunto(s)
Infertilidad Masculina/etiología , Infertilidad Masculina/microbiología , Infecciones por Serratia/complicaciones , Infecciones por Serratia/microbiología , Serratia marcescens/patogenicidad , Animales , Modelos Animales de Enfermedad , Genitales Masculinos/microbiología , Histocitoquímica , Masculino , Ratones Endogámicos BALB C , Técnicas Microbiológicas , Microscopía , Serratia marcescens/aislamiento & purificación
19.
Gen Comp Endocrinol ; 241: 108-117, 2017 01 15.
Artículo en Inglés | MEDLINE | ID: mdl-27317549

RESUMEN

Insulin and ecdysone signaling play a critical role on the growth and development of insects including Bombyx mori. Our previous study showed that Bombyx larvae reached critical weight for metamorphosis between day 3.5 and 4 of the fifth larval instar. The present study showed that the effect of insulin on the accumulation of glycogen in fat body of Bombyx larvae depends on the critical growth period. When larvae are in active growth period (before reaching critical weight), insulin caused increased accumulation of glycogen, while its treatment in larvae at terminal growth period (after critical period) resulted in an increased mobilization of glycogen. During terminal growth period, insulin and 20-hydroxyecdysone (20E) showed an antagonistic effect on the accumulation of fat body glycogen in fed, food deprived and decapitated larvae as well as in isolated abdomens. Insulin treatment decreased the glycogen content, whereas, 20E increased it. Food deprivation and decapitation caused an increase in the transcript levels of insulin receptor (InR) and this increase in InR expression might be attributed to a decrease in synthesis/secretion of insulin-like peptides, as insulin treatment in these larvae showed a down-regulation in InR expression. However, insulin showed an up-regulation in InR in isolated abdomens and it suggests that in food deprived and decapitated larvae, the exogenous insulin may interact with some head and/or thoracic factors in modulating the expression of InR. Moreover, in fed larvae, insulin-mediated increase in InR expression indicates that its regulation by insulin-like peptides also depends on the nutritional status of the larvae. The treatment of 20E in fed larvae showed an antagonistic effect on the transcript levels since a down-regulation in InR expression was observed. 20E treatment also led to a decreased expression of InR in food deprived and decapitated larvae as well as in isolated abdomens. Insulin and 20E also modulated the expression level of ecdysone receptors (EcRB1 and USP1). 20E treatment showed an up-regulation in expression of ecdysone receptors, but only in fed larvae, whereas insulin treatment showed a down-regulation in the expression of EcRB1 and USP1 in all the experimental larvae studied. Further, the data indicates that an up-regulation of ecdysone receptors is associated with an increase in fat body glycogen content, whereas an up-regulation of insulin receptor expression causes glycogen mobilization. The study, therefore, suggests that the insulin and ecdysone signaling are linked to each other and that both insulin and ecdysone are involved in regulating the carbohydrate reserves in B. mori.


Asunto(s)
Bombyx , Ecdisterona/fisiología , Cuerpo Adiposo/metabolismo , Glucógeno/metabolismo , Insulina/fisiología , Animales , Bombyx/genética , Bombyx/crecimiento & desarrollo , Bombyx/metabolismo , Ecdisona/metabolismo , Ecdisterona/metabolismo , Ecdisterona/farmacología , Perfilación de la Expresión Génica , Regulación del Desarrollo de la Expresión Génica , Insulina/metabolismo , Insulina/farmacología , Larva , Metamorfosis Biológica/efectos de los fármacos , Metamorfosis Biológica/genética , Receptor de Insulina/genética , Receptor de Insulina/metabolismo , Receptores de Esteroides/genética , Receptores de Esteroides/metabolismo , Transducción de Señal/efectos de los fármacos , Transducción de Señal/genética
20.
Proc Natl Acad Sci U S A ; 111(16): 6092-7, 2014 Apr 22.
Artículo en Inglés | MEDLINE | ID: mdl-24711430

RESUMEN

For almost a century the plant hormone auxin has been central to theories on apical dominance, whereby the growing shoot tip suppresses the growth of the axillary buds below. According to the classic model, the auxin indole-3-acetic acid is produced in the shoot tip and transported down the stem, where it inhibits bud growth. We report here that the initiation of bud growth after shoot tip loss cannot be dependent on apical auxin supply because we observe bud release up to 24 h before changes in auxin content in the adjacent stem. After the loss of the shoot tip, sugars are rapidly redistributed over large distances and accumulate in axillary buds within a timeframe that correlates with bud release. Moreover, artificially increasing sucrose levels in plants represses the expression of BRANCHED1 (BRC1), the key transcriptional regulator responsible for maintaining bud dormancy, and results in rapid bud release. An enhancement in sugar supply is both necessary and sufficient for suppressed buds to be released from apical dominance. Our data support a theory of apical dominance whereby the shoot tip's strong demand for sugars inhibits axillary bud outgrowth by limiting the amount of sugar translocated to those buds.


Asunto(s)
Carbohidratos/farmacología , Ácidos Indolacéticos/farmacología , Pisum sativum/crecimiento & desarrollo , Brotes de la Planta/crecimiento & desarrollo , Carbono/metabolismo , Flores/efectos de los fármacos , Flores/fisiología , Flores/efectos de la radiación , Luz , Modelos Biológicos , Pisum sativum/efectos de los fármacos , Pisum sativum/efectos de la radiación , Hojas de la Planta/efectos de los fármacos , Hojas de la Planta/fisiología , Hojas de la Planta/efectos de la radiación , Proteínas de Plantas/metabolismo , Brotes de la Planta/efectos de los fármacos , Brotes de la Planta/efectos de la radiación , Transducción de Señal/efectos de los fármacos , Transducción de Señal/efectos de la radiación , Sacarosa/farmacología
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