T he genomes of multicellular eukaryotes are loaded with retrotransposons, parasites that propagate by transcription of their genomes, reverse transcription, and insertion of a new copy into the host genome (1, 2). Waves of replication have formed families of mostly fragmentary or otherwise degenerate retroelements (1, 2). Epigenetic silencing suppresses retrotransposon activity, keeping them f...

C U ~ N O T , STURTEVANT and MORGAN have all shown that a series of mutually allelomorphic forms of coat pattern exists in mice. There are four types of pattern in this series. These in order, from the most hypostatic to the most epistatic, are as follows: ( I ) Non-agouti, the ordinary “self” or “unticked” coat pattern. ( 2 ) Agou t i or better graybellied agouti, the coat pattern seen in the ...

CLEFFMANN (1963) reported that pigment cells of the lethal yellow (A-y/a) genotype change to black immediately upon cultivation, and continue to produce black pigment unless sulfhydryl reagents are added to the culture medium. We have attempted to repeat this observation and have not been able to do so. We also have been unable to indue the synthesis of yellow pigment by adding glutathione to c...

The melanocortin system is composed of the melanocortin peptides, adrenocorticotropic hormone and alpha-, beta-, and gamma-melanocyte-stimulating hormone, the melanocortin receptors (MCRs), and the endogenous antagonists agouti- and agouti-related protein. Melanocortin peptides exert multiple effects upon the host, including anti-inflammatory and immunomodulatory effects. Leukocytes are a sourc...

The present case report refers to a patient from the State of Rondônia, North region of Brazil, attended with clinical suspicion of hepatic echinococcosis. Examination by imaging (ultrasonography and computerized tomography) revealed a conglomerate of cystic lesions, with mobile contents within the cyst. The serology (immunoblot) for Echinococcus sp. was positive (21 and 31 kDa bands). This cas...

This review discusses the various genetic factors and gene products (proteins) related to obesity. The three fundamental mechanisms underlying obesity are: relative increase in energy intake; reLative decrease in energy expenditure; and preferential partitioning of ingested calories to fat storage. Gene defects can be related to any one of these mechanisms, either alone or together. Many geneti...

Heterozygosity for the mouse lethal yellow (Ay) mutation leads to obesity, increased tumor susceptibility and increased activity of the agouti coat color gene; homozygosity for Ay results in embryonic death around the time of implantation. Although these pleiotropic effects have not been separated by recombination, previous studies have suggested that the dominant and recessive effects result f...

BACKGROUND Chronic transplant dysfunction explains the majority of late renal allograft loss and is accompanied by extensive tissue remodeling leading to transplant vasculopathy, glomerulosclerosis and interstitial fibrosis. Matrix proteoglycans mediate cell-cell and cell-matrix interactions and play key roles in tissue remodeling. The aim of this study was to characterize differential heparan ...

Many members of the animal kingdom display coat or skin color differences along their dorsoventral axis. To determine the mechanisms that control regional differences in pigmentation, we have studied how a classical mouse mutation, droopy ear (de(H)), affects dorsoventral skin characteristics, especially those under control of the Agouti gene. Mice carrying the Agouti allele black-and-tan (a(t)...