Molecular characterization of the marker chromosome associated with cat eye syndrome.

Cat eye syndrome (CES) is associated with a supernumerary bisatellited marker chromosome which is derived from duplicated regions of 22pter-22q11.2. In this study we have used dosage and RFLP analyses on 10 CES patients with marker chromosomes, by using probes to five loci mapped to 22q11.2. The sequences recognized by the probes D22S9, D22S43, and D22S57 are in four copies in all patients, but the sequences at the more distal loci, D22S36 and D22S75, are duplicated only in some individuals. D22S36 is present in three copies in some individuals, and D22S75 is present in two copies in the majority of cases. Only three individuals have a duplication of the most distal locus examined (D22S75), and these individuals have the largest marker chromosomes identified in this study. From the dosage analysis it was found that the marker chromosomes are variable in size and can be asymmetric in nature. There is no obvious correlation between the severity of the phenotype and the size of the duplication. The distal boundary of the CES critical region (D22S36) is proximal to that of DiGeorge syndrome, a contiguous-gene-deletion syndrome of 22q11.2.     

Eco-evolution from deep time to contemporary dynamics: The role of timescales and rate modulators

Eco-evolutionary dynamics, or eco-evolution for short, are often thought to involve rapid demography (ecology) and equally rapid heritable phenotypic changes (evolution) leading to novel, emergent system behaviours. We argue that this focus on contemporary dynamics is too narrow: Eco-evolution should be extended, first, beyond pure demography to include all environmental dimensions and, second, to include slow eco-evolution which unfolds over thousands or millions of years. This extension allows us to conceptualise biological systems as occupying a two-dimensional time space along axes that capture the speed of ecology and evolution. Using Hutchinson's analogy: Time is the ‘theatre’ in which ecology and evolution are two interacting ‘players’. Eco-evolutionary systems are therefore dynamic: We identify modulators of ecological and evolutionary rates, like temperature or sensitivity to mutation, which can change the speed of ecology and evolution, and hence impact eco-evolution. Environmental change may synchronise the speed of ecology and evolution via these rate modulators, increasing the occurrence of eco-evolution and emergent system behaviours. This represents substantial challenges for prediction, especially in the context of global change. Our perspective attempts to integrate ecology and evolution across disciplines, from gene-regulatory networks to geomorphology and across timescales, from today to deep time.     

The active site of the P99 beta-lactamase from Enterobacter cloacae.

Labelling the beta-lactamase of Enterobacter cloacae P99 with a poor substrate or a mechanism-based inactivator points to an active-site serine residue in a sequence closely resembling that of the ampC beta-lactamase. These results establish the P99 enzyme as a class-C beta-lactamase, and the concurrence of the two approaches helps to confirm the reliability of determining active-site sequences with the aid of mechanism-based inactivators.     

Reserve carbohydrate in maize stem : [C]glucose and [C]sucrose uptake characteristics

Maize (Zea mays L.) stem is thought to function alternately as a net importing and net exporting organ during ontogeny, depending on whole plant photosynthetic source and sink status. The [¹⁴C]sucrose and [¹⁴C]glucose uptake capacity of stem tissues was investigated to increase our understanding of the transport factors which may influence sink status.     

Isolation of lysine codon suppressors inEscherichia coli

Starting with anEscherichia coli strain containingglyT56, a glycine transfer RNA suppressor of the arginine codons AGA and AGG, and atrpA mutant containing lysine at position 211 of the tryptophan synthetase alpha chain, we have isolated AAG-suppressors that fall into two classes. In class 1 are dominant suppressors that arose with the simultaneous loss ofglyT56 activity. They are approximately 50% cotransducible withargE, as isglyT, and appear to be derived fromglyT56. Class 2 suppressors, located betweenpurE andtrp on theE. coli map, are not near any glycine tRNA genes, and may represent novel missense suppressors.     

Characterization of iron-sulfur clusters in rat liver submitochondrial particles by electron paramagnetic resonance spectroscopy. Alterations produced by chronic ethanol consumption

Iron-sulfur clusters present in rat liver submitochondrial particles were characterized by ESR at temperatures between 30 and 5.5 K combined with potentiometric titrations. The spectral and thermodynamic characteristics of the iron-sulfur clusters were generally similar to those previously reported for pigeon or bovine heart submitochondrial particles. Clusters N-1a, N-1b, N-2, N-3 and N-4 of NADH dehydrogenase had midpoint oxidation-reduction potentials at pH 7.5 of ?425, ?265, ?85, ?240 and ?260 mV, respectively. Clusters S-1 and S-3 of succinate dehydrogenase had midpoint potentials of 0 and +65 mV, respectively. The iron-sulfur cluster of electron-transferring flavoprotein-ubiquinone oxidoreductase exhibited the g_z signal at g = 2.08 and had a midpoint potential of +30 mV. This signal was relatively prominent in rat liver compared to pigeon or bovine heart.Submitochondrial particles from rats chronically treated with ethanol (36% of total calories, 40 days) showed decreases of 20–30% in amplitudes of signals due to clusters N-2, N-3 and N-4 compared to those from pair-fed control rats. Signals from clusters N-1b, S-1, S-3 and electron-transferring flavoprotein-ubiquinone oxidoreductase were unaffected. Microwave power-saturation behavior was similar for both submitochondrial particle preparations, suggesting that the lower signal amplitudes reflected a lower content of these particular clusters. NADH dehydrogenase activity was significantly decreased (46%), whilst succinate dehydrogenase activity was elevated (25%), following chronic ethanol consumption. The results indicate that chronic ethanol treatment leads to an alteration of the structure and function of the NADH dehydrogenase segment of the electron transfer chain. This alteration is one of the factors contributing to the lower respiration rates observed following chronic ethanol administration.     

WOMEN IN NINETEENTH CENTURY AMERICAN BOTANY; A GENERALLY UNRECOGNIZED CONSTITUENCY

Botany was thought to be a suitable study for young women in schools and an amateur avocation in the Nineteenth Century. A surprisingly large number of American women identified themselves as being seriously interested in botany. For example, in the first published directory of American botanists in 1873, 13 percent of the 599 names are women's and that increased to 16 percent of the 982 names in 1878. In this paper, 1,185 women have been identified as a sample of those actively interested in botany during the century. Less than 2% of them were active before 1870, and most of them, 67%, resided in New England and the Middle Atlantic States. Almost three quarters of them were unmarried, and only 10% had higher educational degrees although 15% had some identifiable profession. Some particular individuals are noted for their contributions to science, their activity as plant collectors, and their support of botanical societies. Though few American women became professional botanists in the Nineteenth Century, they constitute an important overlooked constituency for the developing profession of botany.