Dynamics of Cytokinins in Apical Shoot Meristems of a Day-Neutral Tobacco during Floral Transition and Flower Formation1

This study considered cytokinin distribution in tobacco (Nicotiana tabacum L.) shoot apices in distinct phases of development using immunocytochemistry and quantitative tandem mass spectrometry. In contrast to vegetative apices and flower buds, we detected no free cytokinin bases (zeatin, dihydrozeatin, or isopentenyladenine) in prefloral transition apices. We also observed a 3-fold decrease in the content of cytokinin ribosides (zeatin riboside, dihydrozeatin riboside, and isopentenyladenosine) during this transition phase. The group concluded that organ formation (e.g. leaves and flowers) is characterized by enhanced cytokinin content, in contrast to the very low endogenous cytokinin levels found in prefloral transition apices, which showed no organogenesis. The immunocytochemical analyses revealed a differing intracellular localization of the cytokinin bases. Dihydrozeatin and isopentenyladenine were mainly cytoplasmic and perinuclear, whereas zeatin showed a clear-cut nuclear labeling. To our knowledge, this is the first time that this phenomenon has been reported. Cytokinins do not seem to act as positive effectors in the prefloral transition phase in tobacco shoot apices. Furthermore, the differences in distribution at the cellular level may be indicative of a specific physiological role of zeatin in nuclear processes.

Evidence that two present-day components needed for the genetic code appeared after nucleated cells separated from eubacteria.

The trinucleotide/amino acid relationships of the present-day genetic code are established by the amino-acylation reactions of tRNA synthetases, whereby each of 20 specific amino acids is attached to its cognate tRNAs, which bear anticodon trinucleotides. Because of its universality, the appearance of the modern genetic code is thought to predate the separation of prokaryotic and eukaryotic organisms in the universal phylogenetic tree. In the light of new sequence information, we present here a phylogenetic analysis that shows an unusual picture for tyrosyl- and tryptophanyl-tRNA synthetases. Ij particular, the eukaryotic tyrosyl- and tryptophanyl-tRNA synthetases are more related to each other than to their respective prokaryotic counterparts. In contrast, each of the other 18 eukaryotic synthetases is more related to its prokaryotic counterpart than to any eukaryotic synthetase specific for a different amino acid. Our results raise the possibility that present day tyrosyl- and tryptophanyl-tRNA synthetases appeared after the separation of nucleated cells from eubacteria. The results have implications for the development of the genetic code.

A Drosophila seminal fluid protein, Acp26Aa, stimulates egg laying in females for 1 day after mating.

Mating triggers behavioral and physiological changes in the Drosophila melanogaster female, including an elevation of egg laying. Seminal fluid molecules from the male accessory gland are responsible for initial behavioral changes, but persistence of these changes requires stored sperm. Using genetic analysis, we have identified a seminal fluid protein that is responsible for an initial elevation of egg laying. This molecule, Acp26Aa, has structural features of a prohormone and contains a region with amino acid similarity to the egg-laying hormone of Aplysia. Acp26Aa is transferred to the female during mating, where it undergoes processing. Here we report the generation and analysis of mutants, including a null, in Acp26Aa. Females mated to male flies that lack Acp26Aa lay fewer eggs than do mates of normal males. This effect is apparent only on the first day after mating. The null mutation has no other detectable physiological or behavioral effects on the male or the mated female.

Rapid RNA polymerase genetics: one-day, no-column preparation of reconstituted recombinant Escherichia coli RNA polymerase.

We present a simple, rapid procedure for reconstitution of Escherichia coli RNA polymerase holoenzyme (RNAP) from individual recombinant alpha, beta, beta', and sigma 70 subunits. Hexahistidine-tagged recombinant alpha subunit purified by batch-mode metal-ion-affinity chromatography is incubated with crude recombinant beta, beta', and sigma 70 subunits from inclusion bodies, and the resulting reconstituted recombinant RNAP is purified by batch-mode metal-ion-affinity chromatography. RNAP prepared by this procedure is indistinguishable from RNAP prepared by conventional methods with respect to subunit stoichiometry, alpha-DNA interaction, catabolite gene activator protein (CAP)-independent transcription, and CAP-dependent transcription. Experiments with alpha (1-235), an alpha subunit C-terminal deletion mutant, establish that the procedure is suitable for biochemical screening of subunit lethal mutants.

Chronotype and time-of-day effects on mood during school day

Existing evidence suggests an association between mood, time-of-day and Morningness-Eveningness (M-E). Since few studies have been carried out among adolescents, in this study daily mood fluctuations were analyzed in the naturalistic school context during two days in order to test how chronotype and time-of-day are related to mood during the school schedule period and check if sleep length is involved in the above relation. A sample of 655 adolescents (12-16 years) reported mood levels (current level of pleasantness) three times during school day (8:10-8:30 h, 10:20-11:40 h, 13:50-14:10 h). They also reported M-E preference and time in bed. Neither age nor sex was related to mood. However, the results indicated that regardless of chronotype mood increased throughout the school day from the lowest morning levels. Moreover, morning types showed better mood compared to other chronotypes, while evening types exhibited the lowest mood. Evening oriented students slept less than other chronotypes, but time in bed was not involved in the relationship between chronotype and mood. These results suggest that it is not shortened sleep duration responsible for decreased mood in evening oriented students.

A Fair Day's Wages: Liberty, Legality, and Liability Among Denver's Day Laborers

Day laborers occupy an essential position in Denver’s booming construction industry. Day laborers make up a highly flexible, highly effective workforce able to respond to market changes. For day laborers, informal day-labor gathering points provide increased control over working hours and employee-employer relationships when compared to traditional wage labor. Still, recent legislation and policies around irregular migration has forced large numbers of workers who may have benefited from the stability of full-time regular employment into the informal sector. The day laborers’ flexibility also exposes them to employers constantly inventing ways to deny them the wages and benefits they are owed. Despite changes in Colorado law in attempts to strengthen workers’ recourse against their employers, and despite social and individual tactics day laborers employ to mitigate their vulnerability, systematic structural, symbolic, and everyday violence continue to advantage employers.

An investigative and interpretive study, with paintings, drawings and prints, of "All Saints' Day" and "All Souls" Day" in Mexico

"In Mexico, the first two days of November are set aside each year for the commemoration of the dead. This fete, called All Saints' Day and All Souls' Day, is observed throughout the world; however, in Mexico, it is celebrated in a manner peculiar to that country and to the various localities within that country . This holiday is sanctioned by both government and church; and is celebrated by practically all Mexicans, whether they be Catholic, pagan, relilious or irreligious. These are the two days when that contrast which is the essence of Mexico becomes obvious: the "triste~alegria" (sad-happiness). During these days , art objects are abundant and arresting ; and religious ceremonies, rites and fiestas blossom forth! Urban and folk arts, in every field, find full expression at this time. The religious, social, political, and artistic manifestations of the holiday are not only stimulating in themselves, but are exciting as subjects for painting, drawings, prints, and any other form of artistic expression!"

On the status of conversion in present-day American English: controversial issues and corpus-based study

This paper examines both theoretical and practical issues related to conversion. A quite detailed characterization of the 5329 instances identified in a 300.000-word corpus of American English written in the late 90s is provided. The examples are grouped according to the type of conversion involved. Frequency and the internal structure of words are also considered and compared with the results obtained by earlier scholars. In spite of the limitations that a corpus study imposes, the conclusions obtained seem to suggest that any item, independent of its morphological structure, may undergo conversion and this may happen in any register. Moreover, conversion seems to be an important source of new items in American English nowadays.

A new day for the colored woman worker: a study of colored women in industry in New York City

Joint Committee to Study the Employment of Colored Women in New York City and Brooklyn.

The eight hours day for wage earning women: United States Supreme Court upholds the California law : List of eight hours laws

National Consumers' League.

Every-day business for women: a manual for the uninitiated

by Mary Aronetta Wilbur.