A cryptic intermediate in the evolution of chameleon tongue projection

Summary An incipient form of tongue projection occurs inPhrynocephalus helioscopus, a generalized agamid lizard. We argue that this condition represents a functional intermediate between typical lingual prehension and chamaeleontid tongue projection, and that tongue projection evolved in chameleons by augmentation of ancestral mechanisms still operating in related, generalized lizards.     

Autoinhibition of juvenile hormone production. The case of the cockroachBlattella germanica (L.)

In 6-day-old females ofBlattella germanica, the activity of corpora allata (CA) was inhibited in vitro by juvenile hormone III (JH III). Effective doses (281.5 and 375.4 M in the medium) were somewhat higher than (although of the same order of magnitude as) the estimated intraglandular concentration of JH III at this age, and they induced about 45% inhibition of hormonal release and a significant intraglandular accumulation of JH III and methyl farnesoate. The results suggest that autoinhibitory mechanisms operate in the CA to constrain the upper limit of JH III production at the end of the gonadotrophic cycle.     

Sequence of a cDNA clone encoding human preproinsulin-like growth factor II

The insulin-like growth factors (IGF) I and II are single-chain serum proteins of 70 and 67 amino acids, respectively, which are synthesized by the liver and possibly other tissues. They are probably required for normal fetal and postnatal growth and development. They also stimulate the growth of cultured cells, possibly by controlling the progression through the G1 phase of the cell cycle. In contrast to IGF-II whose concentration does not vary during postnatal development, the serum levels of IGF-I increase several-fold to adult levels during puberty. The serum concentration of IGF-I is a sensitive monitor of growth hormone levels and is decreased in individuals with growth hormone deficiency and elevated in those with growth hormone-secreting tumours. As a first step in studying the biosynthesis of these proteins and elucidating their role(s) in normal development and in tumorigenesis, we have isolated and sequenced cDNAs prepared from adult human liver mRNA which encode the precursors to IGF-I and -II. We report here the sequence of a cDNA encoding a 180-amino acid protein which is the precursor to IGF-II.     

Mesencephalic reticular responses to natural and to repeated sensory stimuli

Résumé L'activité des neurones de la formation réticulaire mésencéphalique du chat est modifiée par l'effet de stimuli physiologiques, quelque fois très complexes: la convergence hétéro-sensorielle est très évidente et les champs récepteurs ont différentes étendues et distributions. Soumises à de hautes fréquences de stimulation, les cellules présentent une réactivité limitée. Au fur et à mesure que la stimulation est répétée, les réponses diminuent et, finalement, disparaissent; cette diminution de réactivité est souvent spécifique de la stimulation utilisée.     

Predicting disease using genomics

Information from the human genome sequence will eventually alter many aspects of clinical practice. It will increase through our understanding of disease mechanisms, and guide the development of new drugs and therapeutic procedures. In the short term, however, knowledge of the genome will have a profound clinical impact on the diagnostic capability of clinical genetics laboratories. Molecular phenotyping using genetic and genomic information will allow early and more accurate prediction and diagnosis of disease and of disease progression. Medicine will become oriented towards disease prevention rather than efforts to cure people at late stages of illness.     

Linkage of Rieger syndrome to the region of the epidermal growth factor gene on chromosome 4.

Rieger syndrome is an autosomal dominant disorder of morphogenesis in which previous cytogenetic arrangements have suggested chromosome 4 as a candidate chromosome. Using a group of highly polymorphic short tandem repeat polymorphisms (STRP), including a new tetranucleotide repeat for epidermal growth factor (EGF), significant linkage of Rieger syndrome to 4q markers has been identified. Tight linkage to EGF supports its role as a candidate gene, although a recombinant in an unaffected individual has been identified. This study demonstrates the utility of using polymorphic STRP markers when only a limited number of small families are available for study.