RESUMO
The vitelline membrane (VM), the oocyte proximal layer of the Drosophila eggshell, contains four major proteins (VMPs) that possess a highly conserved "VM domain" which includes three precisely spaced, evolutionarily conserved, cysteines (CX7CX8C). Focusing on sV23, this study showed that the three cysteines are not functionally equivalent. While substitution mutations at the first (C123S) or third (C140S) cysteines were tolerated, females with a substitution at the second position (C131S) were sterile. Fractionation studies showed that sV23 incorporates into a large disulfide linked network well after its secretion ceases, suggesting that post-depositional mechanisms are in place to restrict disulfide bond formation until late oogenesis, when the oocyte no longer experiences large volume increases. Affinity chromatography utilizing histidine tagged sV23 alleles revealed small sV23 disulfide linked complexes during the early stages of eggshell formation that included other VMPs, namely sV17 and Vml. The early presence but late loss of these associations in an sV23 double cysteine mutant suggests that reorganization of disulfide bonds may underlie the regulated growth of disulfide linked networks in the vitelline membrane. Found within the context of a putative thioredoxin active site (CXXS) C131, the critical cysteine in sV23, may play an important enzymatic role in isomerizing intermolecular disulfide bonds during eggshell assembly.
Assuntos
Proteínas de Drosophila/química , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/crescimento & desenvolvimento , Drosophila melanogaster/metabolismo , Proteínas de Membrana/química , Proteínas de Membrana/metabolismo , Membrana Vitelina/crescimento & desenvolvimento , Membrana Vitelina/metabolismo , Sequência de Aminoácidos , Substituição de Aminoácidos , Animais , Animais Geneticamente Modificados , Sequência de Bases , Sítios de Ligação/genética , Sequência Conservada , Cisteína/química , Primers do DNA/genética , Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Evolução Molecular , Feminino , Genes de Insetos , Proteínas de Membrana/genética , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Proteínas Mutantes/química , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismo , Oogênese/genética , Oogênese/fisiologia , Estrutura Terciária de Proteína , Homologia de Sequência de AminoácidosAssuntos
Sarcoidose , Adolescente , Adulto , Fatores Etários , Criança , Feminino , História do Século XIX , História do Século XX , Humanos , Masculino , Radiografia , Sarcoidose/diagnóstico por imagem , Sarcoidose/históriaRESUMO
The diagnosis of subcapsular hematoma of the liver following blunt abdominal trauma has assumed clinical importance with recent reports of improved mortality with conservative management. There is increasing use of hepatic scintigraphy in evaluation of upper abdominal trauma. Two recently observed cases are used to illustrate the typical findings in this entity.
Assuntos
Hematoma/diagnóstico , Hepatopatias/diagnóstico , Cintilografia , Adulto , Criança , Maus-Tratos Infantis , Feminino , Humanos , Fígado/lesões , Masculino , Tecnécio , Ferimentos não Penetrantes/diagnósticoRESUMO
A case of positive tracer localization in a benign tumor of the liver on a 67Ga-citrate scan is reported. The authors were unable to find any previous reports of positive localization of gallium in this type of liver tumor.
Assuntos
Carcinoma Hepatocelular/diagnóstico , Radioisótopos de Gálio , Neoplasias Hepáticas/diagnóstico , Cintilografia , Adulto , Feminino , HumanosRESUMO
The "doughnut" sign in brain scanning was originally described in association with certain mass lesions having central necrotic, cystic, or avascular areas. A case in which this pattern occurred as a result of a superficial lesion, a large cephalhematoma, is presented.
