Identification of the RNA products of the ops gene of Myxococcus xanthus and mapping of ops and tps RNAs.

The expression of the ops gene, like that of the highly homologous and closely linked tps gene, is induced during development of the fruiting bacterium Myxococcus xanthus. The RNA products of the ops gene have been identified and compared with tps RNA. The ops RNA was observed in developmental cells only after spore formation had commenced, and it was necessary to use a sporulation-defective mutant strain or to disrupt spores to isolate this RNA. RNA from the ops gene was not observed in vegetative cells but was readily detected in cells subjected to glycerol-induced sporulation. In contrast, a large amount of developmental tps RNA was observed in cells well before sporulation had occurred; low levels of tps RNA were observed in vegetative cells; and only a slight increase in tps RNA was found during glycerol-induced sporulation. Several ops and tps RNAs were observed in this study, and the positions of these RNAs were mapped on the M. xanthus genome. The 5' ends of both the ops and tps RNAs mapped predominantly to positions about 50 bases upstream from the respective translational initiation sites. The 3' ends of RNAs from both genes were heterogeneous. The four ops RNAs were 620, 775, 845, and 1,230 bases in length, while the tps RNAs were 612, 695, 730, and 935 bases.     

Tn5-mediated transposition of plasmid DNA after transduction to Myxococcus xanthus.

After coliphage P1-mediated transfer of Tn5-containing plasmid DNA from Escherichia coli to Myxococcus xanthus, transductants were identified which contained plasmid sequences integrated at many sites on the bacterial chromosome. The unaltered plasmid DNA sequences in these transductants were apparently flanked by intact Tn5 or IS50 sequences. These results suggest that Tn5-mediated transposition has occurred and provide a method for integrating plasmid DNA into the M. xanthus chromosome without the requirement for homologous recombination.     

Bacterial xanthine oxidase from Arthrobacter S-2.

Arthrobacter S-2, originally isolated by enrichment on xanthine, produced high levels of xanthine oxidase activity, requiring as little as a 20-fold purification to approach homogeneity with some preparations. Molecular oxygen, ferricyanide, and 2,6-dichlorophenol-indophenol served as electron acceptors, but nicotinamide adenine dinucleotide did not. The enzyme was relatively specific when compared with previously studied xanthine-oxidizing enzymes, but at least one purine was observed to be oxidized at each of the three positions of the purine ring that have been subject to oxidation by this type of enzyme. The enzyme had a relatively high Km for xanthine (1.3 X 10(-4) M), and substrate inhibition was not observed with this compound, in contrast to the enzyme from cow's milk. In fact, an opposite effect was observed, and double-reciprocal plots with xanthine as the variable substrate showed a concave downward deviation at high concentrations. At 2.5 mM xanthine the enzyme had a specific activity approximately 50 times that of the most active preparations of the milk enzyme. The spectrum of the Arthrobacter enzyme resembled that of milk xanthine oxidase, suggesting a similarity of the prosthetic centers of the two enzymes. The bacterial enzyme was relatively small and may be dimeric, with approximate native and subunit molecular weights of 146,000 and 79,000, respectively.     

Treatment of hypertonicity in muscles of lip retraction

An EMG biofeedback program was developed for a 56-year-old Parkinsonism patient who exhibited pathological lip hypertonia and retraction. The program was designed to achieve the following goals: (1) to demonstrate a reduction in postural lip hypertonicity and (2) to demonstrate a reduction in lip hypertonicity during a series of increasingly complex speech activities. To achieve the first goal, contrastive tasks of full contraction and relaxation were utilized. Each posture was sustained while voltage measurements were made at specifici intervals. Procedures to modify lip retraction during speech included five tasks in which the patient was to monitor the audio feedback signal. The tasks involved: prolongation of a neutral vowel, consonant-vowel combinations, monosyllabic words, sentences, and a paragraph-reading task. Data collected over six biofeedback sessions are presented. Trend analyses showed consistent muscular reduction within each task. The following explanations for the decrease in the patient's hypertonicity were discussed: (1) reduction of anisometric contraction, (2) reduction of isometric contraction, (3) relearning of agonistic-antagonistic muscle balance.This research was supported in part by the University of Tennessee Neuropathology Services Program.     

Evaluation of Effects of Harvest on Alligator Populations in Louisiana

Biologists with the Louisiana Department of Wildlife and Fisheries, Louisiana, USA, have managed statewide annual harvest of alligators (Alligator mississippiensis) for 35 years (1981–present). We collected and analyzed harvest data for Louisiana alligators to determine the effects of harvest on the population structure, focusing on the larger size classes (≥274 cm) of this slow-growing species. Linear regression analyses revealed that body size-class structure, based on overall average size and the percentage of animals harvested in the larger size classes was relatively stable. Annual aerial alligator nest counts indicated a continual growth of the population, and over time harvested alligators maintained a constant average size. Analyses of population size (based on number of nests and population modeling) indicated that the current annual harvest represents approximately 3% of the population. Linear regression analysis showed that annual hunter success declined only slightly during the study period, and the scheduling of the hunt season after the hatch period and recommended hunting in areas not frequented by breeding females provides economic opportunities for hunters to participate in a sustainable harvest that preserves the larger size classes of alligators in the population. Strict enforcement of existing laws was a key factor responsible for the success of this harvest program. Comparison of alligator population size and number of harvest-related citations indicated that illegal harvest did not have a negative effect on population size, and linear regression analyses revealed that the rate of increase in citations was lower than the increase in populations over the study period. The results of this harvest program indicated that alligators can be hunted in a sustainable manner if hunting is conducted after the hatch period and occurs in areas that primarily exclude the harvest of adult females, and strict law enforcement curbs illegal activities that negatively affect populations. © 2021 The Authors. The Journal of Wildlife Management published by Wiley Periodicals LLC on behalf of The Wildlife Society.     

Is Maternal Marriage Beneficial for Low-Income Adolescents?

The present study investigated the association of mothers' marriage and changes in young adolescents' cognitive and socioemotional development and changes in family processes. Analyses employed longitudinal data from the Three-City Study to track maternal partnerships for 860 low-income adolescents (10–14 years-old in Wave 1) across a 16 month period. No short-term benefits or risks emerged for youth when mothers entered marriage, with few changes in family or maternal functioning linked with marriage formation as well. In contrast, adolescents in stably married families experienced improved academic, behavioral, and psychological well-being compared to youth in stable cohabiting or single-parent families. Stable marriage was similarly linked to improvements across multiple domains of home and mothers' functioning. These patterns were not moderated by the male partner's identity (biological father or stepfather). Results support the benefits of stable marriage on youth development, but suggest that policies supporting movements into new marriages may not result in improved adolescent or family functioning, at least in the short term.