Dominance status and certain operants in a communal colony of rhesus macaques

This study was designed to test the hypothesis that in some species of primates individual differences in responsiveness to certain situations is related to dominance status. During the first phase of the study, the existence of a linear dominance hierarchy was confirmed by ratings of agonistic interactions. In the second phase, bar-pressing behavior was recorded on a cumulative recorder while the experimenter simultaneously rated, at 30-second intervals, all animals present in the research setting. Results indicated that dominance status was systematically related both to rate of bar-pressing and to duration of response blocks, with the more dominant animals bar-pressing at slower rates for longer blocks of time. The finding that individual differences in rate did not vary with social context suggests that dominance-related differences in responsiveness may be quite stable. Certain dominancerelated trends in the variation of social context in the research setting were also noted.     

A convenient pH-gradient method for the determination of the maximum and minimum pH for microbial growth

Previously existing methods for determining the pH limits for the growth of microorganisms have involved (1), the setting up of individual cultures, each having a specific pH; (2), the pH gradient plate technique devised by Sacks (1956) in which a continuous pH gradient is established in a Petri dish by means of a buffer system; and (3), the pH gradient plate technique of Zak (unpublished), in which a continuous pH gradient is established by means of an electric current. The discontinuous pH gradient technique described here provides a convenient method of determining the maximum and minimum pH at which a microorganism can grow. The technique can be used aerobically or anaerobically, and has a precision of about ± 0.1 pH unit. Data are given for several yeasts and forSerratia marcescens. In all cases, the organisms tested continued to metabolize at pH values beyond those representing the limits for growth, sometimes by as much as 0.5 pH unit. The results suggest that pH limits are unsuitable criteria in microbial classification.     

Nucleotide sequence of IS492, a novel insertion sequence causing variation in extracellular polysaccharide production in the marine bacterium Pseudomonas atlantica.

The complete nucleotide sequence of insertion element IS492, which causes reversible inactivation of extracellular polysaccharide production in the marine bacterium Pseudomonas atlantica, is presented. Insertion of IS492 results in the EPS- phenotype, and excision results in restoration of EPS+. DNA sequencing of the site of insertion in the eps locus showed that insertion of IS492 generates a 5-base-pair repeat and that its excision is precise. IS492 is 1,202 nucleotides in length and contains one large open reading frame encoding a protein of 318 amino acids, a candidate for transposition function. No similarity between IS492 and other transposable elements has been found. Unlike the situation with other insertion sequences, no direct or inverted repeats exist at the termini of IS492.     

Reconstruction of late craniofacial deformities after irradiation of the head and face during childhood

Little is known about the results of surgical management of late craniofacial abnormalities arising after irradiation of the head and face for treatment of childhood cancers. The clinical records of 10 children (4 males and 6 females) who received 4500 to 6500 rads (mean 5160 rads) of craniofacial radiation between birth and 8 years of age (mean 5 years) and who subsequently had reconstructive surgery were reviewed. Six of the 10 patients received orbital radiation, 3 received maxillary-midfacial radiation, and 1 patient underwent radiation to the frontal bone. Histologic tumor types included retinoblastoma (4), rhabdomyosarcoma (3), Ewing's sarcoma (2), and neurofibrosarcoma (1). In addition to radiation, 7 of the 10 patients underwent surgical resection or debulking of their tumors and 6 received adjuvant chemotherapy. All patients presented from 4 to 20 years after treatment (mean 10 years) with varying, but severe degrees of soft-tissue and bony hypoplasia of the irradiated territories. Onlay bone grafting with soft-tissue reconstruction by a combination of local pedicle flaps and dermal-fat grafts was initially performed in 9 patients, and an occipitoparietal bone-flap switch procedure was done in 1 patient. Late follow-up ranged from 11 months to 7.5 years (mean 34 months). A total of 8 secondary procedures were necessary in 4 of the 10 patients (40 percent). Of these 4 patients, major revisions were performed in 3 and minor adjustments in 1. In addition, 2 patients in whom secondary procedures had not been done would benefit from further reconstruction. Therapy for cancer of the head and face during childhood has profound and ongoing effects on the growth of soft tissue and bone.(ABSTRACT TRUNCATED AT 250 WORDS)     

Relative apparent synapomorphy analysis (RASA). I: The statistical measurement of phylogenetic signal

We have developed a new approach to the measurement of phylogenetic signal in character state matrices called relative apparent synapomorphy analysis (RASA). RASA provides a deterministic, statistical measure of natural cladistic hierarchy (phylogenetic signal) in character state matrices. The method works by determining whether a measure of the rate of increase of cladistic similarity among pairs of taxa as a function of phenetic similarity is greater than a null equiprobable rate of increase. Our investigation of the utility and limitations of RASA using simulated and bacteriophage T7 data sets indicates that the method has numerous advantages over existing measures of signal. A first advantage is computational efficiency. A second advantage is that RASA employs known methods of statistical inference, providing measurable sensitivity and power. The performance of RASA is examined under various conditions of branching evolution as the number of characters, character states per character, and mutations per branch length are varied. RASA appears to provide an unbiased and reliable measure of phylogenetic signal, and the general approach promises to be useful in the development of new techniques that should increase the rigor and reliability of phylogenetic estimates.      

Variation in heat-shock proteins among species of desert fishes (Poeciliidae, Poeciliopsis)

Analysis of the heat-shock proteins (hsps) of six closely related species of Poeciliopsis demonstrated the existence of biochemical diversity in the hsp100, hsp70, hsp60, and hsp30 protein families among species. Each species expressed five to seven hsp70-related isoforms. Constitutive 70-kD isoforms were identical among species, but four different patterns of heat-inducible isoforms were seen in these six species. Members of the hsp70 family of molecular chaperones are included among the most highly conserved proteins known, and the possibility of variation in hsp70 among closely related species has rarely been addressed. The hsp30 family is known to be less conserved than the hsp70 family, and, as expected, the Poeciliopsis hsp30 patterns showed more variation. Most of the hsp30 isoforms characteristic of a particular species were unique to that species. Hsp100 and hsp60 were identical in five of the species, but alternate isoforms were found in P. monacha. The small size and limited geographical distribution of the P. monacha population have probably contributed to the uniqueness of the monacha pattern. Two of the species were shown to acquire thermotolerance, the ability to withstand normally lethal temperatures when subjected to a gradual temperature increase. Rapid-heating protocols commonly used to establish critical thermal maxima of organisms do not include this inducible component of thermoresistance and therefore do not adequately assess an organism's capacity to withstand thermal stress.