The transcription factor E74 is one of the early genes induced by ecdysteroids during metamorphosis of Drosophila melanogaster. Here, we report the cloning and hormonal regulation of E74 from the tobacco hornworm, Manduca sexta (MsE74). MsE74 is 98% identical to that of D. melanogaster within the DNA-binding ETS domain of the protein. The 5’-isoform-specific regions of MsE74A and MsE74B share significantly lower sequence similarity (30-40%). Developmental expression by Northern blot analysis reveals that, during the 5th larval instar, MsE74B expression correlates with pupal commitment on day 3 and is induced to maximal levels within 12h by low levels of 20-hydroxyecdysone (20E) and repressed by physiologically relevant levels of juvenile hormone I (JH I). Immunocytochemical analysis shows that MsE74B appears in the epidermis before the 20E-induced Broad transcription factor that is correlated with pupal commitment (Zhou and Riddiford, 2001). In contrast, MsE74A is expressed late in the larval and the pupal molts when the ecdysteroid titer has declined to low levels and in the adult molt just as the ecdysteroid titer begins to decline. This change in timing during the adult molt appears not to be due to the absence of JH as there was no change during the pupal molt of allatectomized animals. When either 4th or 5th instar larval epidermis was explanted and subjected to hormonal manipulations, MsE74A induction occurred only after exposure to 20E followed by its removal. Thus, MsE74B appears to have a similar role at the onset of metamorphosis in Manduca as it does in Drosophila, whereas MsE74A is regulated differently at pupation in Manduca than at pupariation in Drosophila.

With increasingly detailed images of nuclear structures revealed by advanced microscopy, a remarkably compartmentalized cell nucleus has come into focus. Although this complex nuclear organization remains largely unexplored, some progress has been made in deciphering the functional aspects of various subnuclear structures, revealing how this elaborate framework can influence gene activation. Several recent studies have helped illustrate how cells might utilize the nuclear architecture as an additional level of transcriptional control, perhaps by targeting genes and regulatory factors to specific sites within the nucleus that are designated for active RNA synthesis.

Sum-frequency vibrational spectroscopy was employed to study surface glass transition of

poly(vinyl alcohol) by monitoring the relaxation of rubbing-induced alignment of surface chains with

increase of temperature. The observed chain relaxation is two-dimensional, parallel to the surface. The

surface transition temperature is 58 ( 2 °C, essentially the same as the bulk one.

Oblique dendrites of CA1 pyramidal neurons predominate in stratum radiatum and receive approximately 80% of the synaptic input from Schaffer collaterals. Despite this fact, most of our understanding of dendritic signal processing in these neurons comes from studies of the main apical dendrite. Using a combination of Ca2+ imaging and whole-cell recording techniques in rat hippocampal slices, we found that the properties of the oblique dendrites differ markedly from those of the main dendrites. These different properties tend to equalize the Ca2+ rise from single action potentials as they backpropagate into the oblique dendrites from the main trunk. Evidence suggests that this normalization of Ca2+ signals results from a higher density of a transient, A-type K+ current [I(K(A))] in the oblique versus the main dendrites. The higher density of I(K(A)) may have important implications for our understanding of synaptic integration and plasticity in these structures.

The developmental mechanisms that regulate the relative size and shape of organs have remained obscure despite almost a century of interest in the problem and the fact that changes in relative size represent the dominant mode of evolutionary change. Here, I investigate how the Hox gene Ultrabithorax (Ubx) instructs the legs on the third thoracic segment of Drosophila melanogaster to develop with a different size and shape from the legs on the second thoracic segment. Through loss-of-function and gain-of-function experiments, I demonstrate that different segments of the leg, the femur and the first tarsal segment, and even different regions of the femur, regulate their size in response to Ubx expression through qualitatively different mechanisms. In some regions, Ubx acts autonomously to specify shape and size, whereas in other regions, Ubx influences size through nonautonomous mechanisms. Loss of Ubx autonomously reduces cell size in the T3 femur, but this reduction seems to be partially compensated by an increase in cell numbers, so that it is unclear what effect cell size and number directly have on femur size. Loss of Ubx has both autonomous and nonautonomous effects on cell number in different regions of the basitarsus, but again there is not a strong correlation between cell size or number and organ size. Total organ size appears to be regulated through mechanisms that operate at the level of the entire leg segment (femur or basitarsus) relatively independently of the behavior of individual subpopulations of cells within the segment.

Insulin signaling controls organ growth and final body size in insects. Recent results have begun to clarify how insulin signaling drives organ growth to match nutrient levels, but have not yet elucidated how insulin signaling controls final body size.

Schaffer collateral axons form excitatory synapses that are distributed across much of the dendritic arborization of hippocampal CA1 pyramidal neurons. Remarkably, AMPA-receptor-mediated miniature EPSP amplitudes at the soma are relatively independent of synapse location, despite widely different degrees of dendritic filtering. A progressive increase with distance in synaptic conductance is thought to produce this amplitude normalization. In this study we examined the mechanism(s) responsible for spatial scaling by making whole-cell recordings from the apical dendrites of CA1 pyramidal neurons. We found no evidence to suggest that there is any location dependence to the range of cleft glutamate concentrations found at Schaffer collateral synapses. Furthermore, we observed that release probability (Pr), paired-pulse facilitation and the size of the readily releasable vesicular pool are not dependent on synapse location. Thus, there do not appear to be any changes in the fundamental presynaptic properties of Schaffer collateral synapses that could account for distance-dependent scaling. On the other hand, two-photon uncaging of 4-methoxy-7-nitroindolinyl-caged L-glutamate onto isolated dendritic spines shows that the number of postsynaptic AMPA receptors per spine increases with distance from the soma. We conclude, therefore, that the main synaptic mechanism involved in the production of distance-dependent scaling of Schaffer collateral synapses is an elevated postsynaptic AMPA receptor density.

We present an efficient Monte Carlo algorithm for simulating diffusion in tight-fitting host–guest systems, based on using zeolitenormal modes. Computational efficiency is gained by sampling framework distortions using normal-mode coordinates, and by exploiting the fact that zeolite distortion energies are well approximated by harmonic estimates. Additional savings are obtained by performing local normal-mode analysis, i.e., only including the motions of zeolite atoms close to the jumping molecule, hence focusing the calculation on zeolite distortions relevant to guest diffusion. We performed normal-mode analysis on various silicalite structures to demonstrate the accuracy of the harmonic approximation. We computed free energy surfaces for benzene in silicalite, finding excellent agreement with previous theoretical studies. Our method is found to be orders-of-magnitude faster than comparable Monte Carlo calculations that use conventional forcefields to quantify zeolite distortion energies. For tight-fitting guests, the efficiency of our new method allows flexible-lattice simulations to converge in less CPU time than that required for fixed-lattice simulations, because of the increased likelihood of jumping through a flexible lattice.

Tumorigenesis requires sequential accumulation of multiple genetic lesions. In the prostate, tumor initiation is often linked to loss of heterozygosity at the Nkx3.1 locus. In mice, loss of even one Nkx3.1 allele causes prostatic epithelial hyperplasia and eventual prostatic intraepithelial neoplasia (PIN) formation. Here we demonstrate that Nkx3.1 allelic loss extends the proliferative stage of regenerating luminal cells, leading to epithelial hyperplasia. Microarray analysis identified Nkx3.1 target genes, many of which show exquisite dosage sensitivity. The number of Nkx3.1 alleles determines the relative probabilities of stochastic activation or inactivation of a given target gene. Thus, loss of a single Nkx3.1 allele likely results in hyperplasia and PIN by increasing the probability of completely inactivating select Nkx3.1-regulated pathways within a subset of affected cells.

Using imidazole as promotion agent, primary, secondary and phenolic alcohol compounds were esterified with aliphatic and aromatic carboxylic acid anhydrides. Heating a ternary mixture of alcohol, anhydride and imidazole in an unmodified microwave oven produced esters in low to high yields, depending on the steric bulk of the alcohol.