MAJOR CLADES OF THE ANGIOSPERMS

Abstract— Our knowledge of fundamental angiosperm interrelationships is still very incomplete. The absence of a narrowly circumscribed gymnosperm outgroup, ideally the sister group, makes character evaluation, necessary for a cladistic analysis, difficult. According to current views the superorder Magnoliiflorae with a number of other groups, for example the monocotyledons, may represent a complex of families near the base of the angiosperms. Interrelationships of groups within the monocotyledons are much better understood than those between groups within the dicotyledons. A cladogram of monocotyledon orders based on earlier work by R. Dahlgren, H. T. Clifford, and F. N. Rasmussen is presented. A data matrix for a sample of the angiosperms with 61 characters for 49 taxa, mostly magnoliifloran and related families, is presented. The characters are polarized mainly according to the current view that the primitive angiosperm morphotype is a woody dicotyledon with strobiloid flowers. As an alternative the matrix is adjusted following W. C. Burger's conjecture that the primitive angiosperm was a herbaceous monocotyledon with trimerous flowers. Both matrices were run in a computerized parsimony analysis, resulting in numerous equally parsimonious solutions. This result is illustrative of the great homoplasy in the available character information, and also of how little actually is known about fundamental angiosperm interrelationships or phylogeny.     

Assignment of orthologous relationships among mammalian alpha-globin genes by examining flanking regions reveals a rapid rate of evolution

In order to study the relationships among mammalian alpha-globin genes, we have determined the sequence of the 3' flanking region of the human alpha 1 globin gene and have made pairwise comparisons between sequenced alpha-globin genes. The flanking regions were examined in detail because sequence matches in these regions could be interpreted with the least complication from the gene duplications and conversions that have occurred frequently in mammalian alpha-like globin gene clusters. We found good matches between the flanking regions of human alpha 1 and rabbit alpha 1, human psi alpha 1 and goat I alpha, human alpha 2 and goat II alpha, and horse alpha 1 and goat II alpha. These matches were used to align the alpha-globin genes in gene clusters from different mammals. This alignment shows that genes at equivalent positions in the gene clusters of different mammals can be functional or nonfunctional, depending on whether they corrected against a functional alpha-globin gene in recent evolutionary history. The number of alpha-globin genes (including pseudogenes) appears to differ among species, although highly divergent pseudogenes may not have been detected in all species examined. Although matching sequences could be found in interspecies comparisons of the flanking regions of alpha- globin genes, these matches are not as extensive as those found in the flanking regions of mammalian beta-like globin genes. This observation suggests that the noncoding sequences in the mammalian alpha-globin gene clusters are evolving at a faster rate than those in the beta-like globin gene clusters. The proposed faster rate of evolution fits with the poor conservation of the genetic linkage map around alpha-globin gene clusters when compared to that of the beta-like globin gene clusters. Analysis of the 3' flanking regions of alpha-globin genes has revealed a conserved sequence approximately 100-150 bp 3' to the polyadenylation site; this sequence may be involved in the expression or regulation of alpha-globin genes.      

M1 Muscarinic Acetylcholine Receptor in Cultured Rat Neostriatum Regulates Phosphoinositide Hydrolysis

Abstract: : Muscarinic acetylcholine receptor expression and function in cultured rat neostriatal neurons were examined. All experiments were performed on intact neurons grown in vitro for 12-14 days. The muscarinic antagonist N-[³H]methylscopolamine ([³H]NMS) binds to a single site in cultures with a K_D of 89 pM and a B_max of 187 fmol/mg of protein, or 32,000 sites/neuron. Competition studies using [³H]NMS were performed to determine what receptor sur > types were present. Nonlinear analysis of competition curves was best described with a single binding site for atropine, pirenzepine, and AF-DX 116 {11-[[2-[(diethylamino)-methyl]-1-piperidinyl]acetyl]-5,11-dihydro-6H-pyrido[2,3-b][1,4]benzodiazepine-6-one}, with K_i values of 0.6, 62, and 758 nM, respectively. These results indicate that the muscarinic receptors present in neostriatal cultures are of the M₁subtype, having high affinity for pirenzepine and low affinity for AF-DX 116. In contrast with antagonists, carbachol displaced [³H]NMS from two sites with K_i values of 6.5 and 147 μM, with the higher-affinity form predominant (83% of sites). The M₁ receptor subtype was linked to phosphoinositide turnover. Carbachol stimulated the formation of phosphoinositides with an EC₅₀ of 37 μM and was antagonized by atropine. At equimolar doses, pirenzepine was more potent than AF-DX 116 at antagonizing the response.     

P48-Triggered transmembrane signaling transduction of human monocytes:mobilization of calcium ion and activation of protein kinase C(PKC)

INTRODUCTI0NThedifferentiati0nofcelIsalongthemonocyte-macr0phagepathwayandthesig-nalsinvo1vedinthesecel1sacquiringtheabilitytokilltum0rcellsarenotfllllyundersto0d.Wehavebeenstudingamoleculewhichappearst0beanimportantmemberofthecytokinenetworkinvo1vedintheregulati0nmonocyteactivation.ThiscytokinetermedP48wasisolatedfr0mthehllmannullcellleukemiacell1ineReh.IthasbeenpurifiedtohomogeneityandfOundtobedistinctfrominterferongamma,col0nystimulatingfactors(CSFs)andTNFalphaalldbeta[1,2].Func-ti…     

Ultrafast protein determinations using microwave enhancement

We present here microwave-based modifications of standard protein assays that dramatically reduce the time required to determine protein concentrations. Typical protein determinations involve incubation times ranging from 15–60 min. Microwave irradiation of specimens reduces this time requirement to 10–20 s without compromising accuracy or reliability. The remarkable speed with which protein determinations may be carried out using microwave enhancement greatly simplifies general laboratory procedures that depend on the estimation of protein concentrations. An erratum to this article is available at .     

Performance of a new dynamic model for predicting diurnal time courses of stomatal conductance at the leaf level

Under natural conditions, plants are subjected to continuous changes of irradiance that drive variations of stomatal conductance to water vapour (g_s). We propose a dynamic model to predict the temporal response of g_s at the leaf level using an asymmetric sigmoid function with a unique parameter describing time constants for increasing and decreasing g_s. The model parameters were adjusted to observed data using Approximate Bayesian Computation. We tested the model performance for (1) instant changes of irradiance; or (2) continuous and controlled variations of irradiance simulating diurnal time courses. Compared with the two mostly used steady‐state models, our dynamic model described daily time courses of g_s with a higher accuracy. In particular, it was able to describe the hysteresis of g_s responses to increasing/decreasing irradiance and the resulting rapid variations of intrinsic water‐use efficiency. Compared to the mechanistic model of temporal responses of g_s by Kirschbaum, Gross & Pearcy, for which time constants were estimated with a large variance, our model estimated time constants with a higher precision. It is expected to improve predictions of water loss and water‐use efficiency in higher scale models by using a small number of parameters.     

Prenatal nicotine affects catecholamine gene expression in newborn rat carotid body and petrosal ganglion

Nicotine exposure modifiesthe expression of catecholamine and opioid neurotransmitter systemsinvolved in attenuation of hypoxic chemosensitivity. We used insitu hybridization histochemistry to determine the effect of prenataland early postnatal nicotine exposure on tyrosine hydroxylase (TH),dopamine -hydroxylase (DH), preproenkephalin (PPE), andD₂-dopamine receptor mRNA levels in the rat carotid bodyand petrosal ganglion during postnatal development. In the carotidbody, nicotine increased TH mRNA expression in animals at 0 and 3 postnatal days (both, P < 0.05 vs. control) withoutaffecting TH mRNA levels at 6 and 15 days. At 15 postnatal days, DHmRNA levels were increased in the carotid body of nicotine-exposed animals. Dopamine D₂-receptor mRNA levels in the carotidbody increased with postnatal age but were unaffected by nicotineexposure. PPE was not expressed in the carotid body at any of the agesstudied in control or treated animals. In the petrosal ganglion,nicotine increased the number of ganglion cells expressing TH mRNA inanimals at 3 days (P < 0.01 vs. control). DH mRNAexpression was not induced nor was PPE mRNA expression increased in thepetrosal ganglion in treated animals. Prenatal nicotine exposureupregulates mRNAs involved in the synthesis of two inhibitoryneuromodulators, dopamine and norepinephrine, in peripheral arterialchemoreceptors, which may contribute to abnormalities incardiorespiratory control observed in nicotine exposed animals.

     

The role of static features of males in the mate choice behavior of female Japanese quail (Coturnix japonica)

In two experiments, we investigated the mate choice behavior of female Japanese quail toward taxidermically-prepared male models. Both experiments consisted of four phases: (1) habituation; (2) a pre-test in which two taxidermically-prepared models of male birds were presented; (3) observation in which the respective non-preferred male model was presented either alone or with another stimulus, and (4) a post-test in which male models were again presented alone. Results showed that focal females increased their preference for a non-preferred male model that they had previously observed with a live female (Experiment 1) or with a taxidermically-prepared female model (Experiment 2). Two control groups ruled out the possibility that focal females were choosing male models either because: (1) males were presented with an additional stimulus, or (2) females were choosing an area where they observed male models with other females. The findings suggest that female quail may utilize static, species-specific features of male conspecifics in mate choice.     

Ecological mechanisms of population change during outbreaks of the spruce budworm

Abstract.  1. Stage-specific survival and recruitment of spruce budworm were measured by frequent sampling of foliage in four outbreak populations over a 15-year period in Ontario and Quebec, Canada.
2. Patterns of change in population density during the outbreak collapse phase were closely linked to changes in survival of the late immature stages, and were determined largely by the impact of natural enemies.
3. Host-plant feedback also contributed significantly to survival patterns throughout the outbreak: annual defoliation influenced survival of fourth and fifth instars and fecundity while cumulative defoliation influenced survival of the very early larval stages (first and second) via impacts on stand condition.
4. Inclusion of this host-plant feedback reveals spruce budworm population dynamics as a function of density-related trophic interactions that vary in their order and strength of influence over time. This view re-introduces the importance of forest interactions as a component of dynamics of the spruce budworm.