The kinetics of ACTH expression in rat leukocyte subpopulations

The peripherin gene has three potential ATG translation initiation sites at positions 38, 56, and 290. The second ATG has been proposed to be the initiation codon used for translation of the protein, but there is no experimental evidence for this conjecture. We have isolated a full-length peripherin cDNA (designated as p61-11) from a rat brain cDNA library. Upon sequencing, we found that this cDNA contains a point mutation at the second potential translation initiation codon, which changes this ATG to ACG. When expressed in SW13 cl.2 vim- cells, a cell line without any detectable cytoplasmic intermediate filaments, the protein product of p61-11 cannot form a filamentous network and the major product is 45 kDa in size, which is most likely initiated from the third ATG. The protein product from the first ATG (57 kDa in size) of p61-11 is also detected albeit in smaller amounts. We introduced a frame-shift mutation upstream of the third ATG in p61-11 to create p61-11FS and showed that the third ATG is able to initiate translation efficiently even in the presence of the first ATG, and the 45 kDa protein leads to a diffuse nonfilamentous staining pattern in vim- cells confirming that the first ATG may not be the preferred translation initiation codon, since it cannot suppress a downstream ATG. We increased the translation efficiency from the first ATG of p61-11 by mutating the three nucleotides preceding this first ATG and thereby placing it in a better Kozak consensus sequence for translation initiation. The resulting 57 kDa protein is able to form a filamentous network in vim- cells. We corrected the mutation in the original p61-11 by polymerase chain reaction and generated two peripherin constructs: perM1M2 (which contains all three translation initiation codons) and per delta 1M2 (the first ATG is deleted, but the other two are present). When transfected, their protein products, about 57 kDa in size, form filamentous networks in the absence of other cytoplasmic intermediate filaments. Since there is no 45 kDa protein detected for these latter two constructs, it is reasonable to conclude that in the presence of the second ATG, little or no translation is initiated from the third ATG. Taken together, these results strongly suggest that the second ATG is the preferred translation initiation codon for the peripherin gene.     

The detection and documentation of trace wound patterns by use of an alternative light source

This article is a discussion of the use of narrow-band light sources coupled with cameras equipped with band-pass filters to document patterned injuries on human skin. Several case reports are included.     

Pollination-enhanced expression of a receptor-like protein kinase related gene in tobacco styles

We have isolated a putative serine/threonine receptor kinase gene with an expression pattern indicating that it may play a role in the stylar response to pollination. Differential display PCR was used to select tobacco mRNAs with increased accumulation following pollination. NTS16, a cDNA identified by this method, is homologous to a ca. 2.4 kb mRNA primarily expressed in pistil tissues. Levels of this mRNA increase during floral development and are further increased by pollination reaching maximal accumulation 12-18 hours after pollination and then declining. mRNA levels can also be increased by the application of ethylene to unpollinated flowers. A polypeptide encoded by the NTS 16 open reading frame has sequence similarity to the catalytic domain of several receptor protein kinases from plants including the S-receptor kinases implicated in the rejection of self-pollen in Brassica species and the Pto gene product of tomato which confers resistance to a bacterial pathogen.     

Sensitization of the acoustic startle reflex by footshock.

Administration of footshock (500-ms duration, 0.2–2.4 mA) increased the amplitude of the startle reflex for a long time after its presentation. The effect occurred with a single footshock, although its magnitude and consistency across animals were greater with 5 or 10 footshocks presented 1/s. The facilitatory effect came on within 2–4 min with a 0.6-mA shock, peaking in about 10 min and then dissipating over the next 40 min. Stronger shocks also increased startle, but with a more delayed onset of facilitation (8–20 min). Footshocks increased startle in rats not previously given startle-eliciting stimuli, indicating sensitization rather than dishabituation. The facilitatory effect may not be attributable to a rapid conditioning to the experimental context, because a change in lighting conditions from shock presentation to testing did not attenuate shock sensitization. This excitatory effect of shock on startle may represent the unconditioned effect of shock that can become associated with a neutral stimulus to support classical fear conditioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)