Fission-fusion social organization inAteles andPan

Recent research on the ecology and behavior of free-ranging spider monkeys (Ateles paniscus chamek) allows a more detailed comparison with the chimpanzee,Pan troglodytes, than has been possible previously. Despite their distant common ancestry, chimpanzees and spider monkeys share an unusual fission-fusion social system. In this paper, I compare subgroup size and composition, social unit structure, ranging behavior, patterns of philopatry and dispersal, and social relationships in the two taxa. It is proposed that spatial and temporal patchiness in food dispersion and abundance, resulting in a high-level of feeding competition between females within a group, has been the most important ecological selection pressure leading to the evolution of fission-fusion social organization in both species.     

Organization and chromosomal localization ofβ-tubulin genes inLeishmania donovani

The genomic organization and chromosomal location of theβ-tubulin isogenes inLeishmania donovani promastigotes has been studied by nucleic acid hybridization techniques using a cloned β-tubulin gene. We have cloned aβ-tubulin gene fragment, 3.3 kbp long, from genomic DNA ofLeishmania donovani using a heterologousβ-tubulin DNA as probe. Restriction maps of this clone have been prepared. It has been estimated that there are approximately 11–15 copies of theβ-tubulin genes per haploid genome. The majority of these isogenes are arranged in a tandem repeat with a length of 3.5 kbp on a single chromosome. In addition a few dispersed gene copies at different chromosomal loci were detected by pulse field gradient gel electrophoresis. Part of the internal coding region of the gene has been sequenced to confirm the identity of theβ-tubulin clone and is found to be nearly identical to that ofLeishmania mexicana amazonensis.     

Ferritin gene organization: Differences between plants and animals suggest possible kingdom-specific selective constraints

Ferritin, a protein widespread in nature, concentrates iron ∼10¹¹–10¹²-fold above the solubility within a spherical shell of 24 subunits; it derives in plants and animals from a common ancestor (based on sequence) but displays a cytoplasmic location in animals compared to the plastid in contemporary plants. Ferritin gene regulation in plants and animals is altered by development, hormones, and excess iron; iron signals target DNA in plants but mRNA in animals. Evolution has thus conserved the two end points of ferritin gene expression, the physiological signals and the protein structure, while allowing some divergence of the genetic mechanisms. Comparison of ferritin gene organization in plants and animals, made possible by the cloning of a dicot (soybean) ferritin gene presented here and the recent cloning of two monocot (maize) ferritin genes, shows evolutionary divergence in ferritin gene organization between plants and animals but conservation among plants or among animals; divergence in the genetic mechanism for iron regulation is reflected by the absence in all three plant genes of the IRE, a highly conserved, noncoding sequence in vertebrate animal ferritin mRNA. In plant ferritin genes, the number of introns (n= 7) is higher than in animals (n= 3). Second, no intron positions are conserved when ferritin genes of plants and animals are compared, although all ferritin gene introns are in the coding region; within kingdoms, the intron positions in ferritin genes are conserved. Finally, secondary protein structure has no apparent relationship to intron/exon boundaries in plant ferritin genes, whereas in animal ferritin genes the correspondence is high. The structural differences in introns/exons among phylogenetically related ferritin coding sequences and the high conservation of the gene structure within plant or animal kingdoms suggest that kingdom-specific functional constraints may exist to maintain a particular intron/exon pattern within ferritin genes. In the case of plants, where ferritin gene intron placement is unrelated to triplet codons or protein structure, and where ferritin is targeted to the plastid, the selection pressure on gene organization may relate to RNA function and plastid/nuclear signaling. Received: 25 July 1995 / Accepted: 3 October 1995     

Aspects of the reproductive biology of the concha wrasse, Nelabrichthys ornatus, at Tristan da Cunha

Synopsis The reproductive biology of the concha wrasse, Nelabrichthys ornatus, at Tristan da Cunha in the South Atlantic Ocean is described. Histological evidence shows that the species is a monandric protogynous hermaphrodite. N. ornatus displays full permanent sexual dichromatism with all males occurring in the upper size classes of the population. Size specific habitat preference is described. Aspects of the mating system of the species resemble a lek although the possibility of mating site selection by females is not discounted. Spawning groups have a sex ratio of between 4 and 7 females per male.     

Bacteriochlorophyll organization and energy transfer kinetics in chlorosomes from Chloroflexus aurantiacus depend on the light regime during growth

We have used measurements of fluorescence and circular dichroism (CD) to compare chlorosome-membrane preparations derived from the green filamentous bacterium Chloroflexus aurantiacus grown in continuous culture at two different light-intensities. The cells grown under low light (6 mol m^–2 s^–1) had a higher ratio of bacteriochlorophyll (BChl) c to BChl a than cells grown at a tenfold higher light intensity; the high-light-grown cells had much more carotenoid per bacteriochlorophyll.The anisotropy of the Q_Y band of BChl c was calculated from steady-state fluorescence excitation and emission spectra with polarized light. The results showed that the BChl c in the chlorosomes derived from cells grown under high light has a higher structural order than BChl c in chlorosomes from low-light-grown cells. In the central part of the BChl c fluorescence emission band, the average angles between the transition dipole moments for BChl c molecules and the symmetry axis of the chlorosome rod element were estimated as 25° and 17° in chlorosomes obtained from the low- and high-light-grown cells, respectively.This difference in BChl organization was confirmed by the decay associated spectra of the two samples obtained using picosecond single-photon-counting experiments and global analysis of the fluorescence decays. The shortest decay component obtained, which probably represents energy-transfer from the chlorosome bacteriochlorophylls to the BChl a in the baseplate, was 15 ps in the chlorosomes from high-light-grown cell but only 7 ps in the preparation from low-light grown cells. The CD spectra of the two preparations were very different: chlorosomes from low-light-grown cells had a type II spectrum, while those from high-light-grown cells was of type I (Griebenow et al. (1991) Biochim Biophys Acta 1058: 194–202). The different shapes of the CD spectra confirm the existence of a qualitatively different organization of the BChl c in the two types of chlorosome.Abbreviations BChl bacteriochlorophyll - CD circular dichroism - DAS decay associated spectrum - PMSF phenylmethylsulfonyl fluoride     

Stimulus enhancement and spread of a spontaneous tool use in a colony of long-tailed macaques

In a captive group of long-tailed macaques, tool-using behavior by a single competent individual had a significant effect on the synchronous manipulative behavior of naïve animals. Group members engaged in manipulations on the same object class more frequently during times when the model was working than when it was not. The form of their behavior, however, in no way resembled the technique used by the model. All three animals that later became successful tool users were among the few subjects that exhibited a significant increase in manipulations on the same object class while the model was working. Possible causal relationships between this stimulus enhancement and the transmission of the new behavior to other group members are analyzed and discussed.     

Consistent handedness of microtubule helical arrays in maize and Arabidopsis primary roots

Summary The orientation of cortical microtubules in plant cells has been extensively studied, in part because of their influence on the expansion of most plant cell types. Cortical microtubules are often arranged in helical arrays, which are well known to occur with a specific pitch as a function of development or experimental treatment; however, it is not known if the handedness of helical arrays can also be specified. We have studied the handedness of helical arrays by using Vibratome sectioning of maize primary roots and confocal microscopy of Arabidopsis primary roots. In cortical cells of maize roots, the helical array was found to have the same handedness at a given position, not only for the cells of a single root, but also for the cells of more than one hundred roots examined. Quantification of angular distribution of apparent individual microtubules showed that defined regions of the root were composed of cells with highly uniform microtubule orientation. In the region between transverse and longitudinal microtubules (5–10.5 mm from the tip), the array formed a right-handed helix, and basal of cells with longitudinal microtubules (11.5–15 mm from the tip), the array formed a left-handed helix. Similarly, in epidermal cells of Arabidopsis roots right-handed helical arrays were found in the region between transverse and longitudinal microtubules. These results suggest that, in addition to the orientation of microtubules, the handedness of helical microtubule arrays is under cellular control.Abbreviations Cy3 indocarbocyanine - PBS phosphate-buffered saline - PIPES piperazine-N,N-bis-[2-ethanesulfonic acid]     

Prestige,possessions, and progeny

It has been suggested by some that the acquisition of symbolic capital in terms of honor, prestige, and power translates into an accumulation of material capital in terms of tangible belongings, and that on the basis of these goods high reproductive success may be achieved. However, data on completed fertility rates over more than one generation in so-called traditional societies have been rare. Ethnographic and demographic data presented here on the pastoral Bakkarwal of northern India largely corroborate the hypothesis concerning the interdependence between the attainment of various cultural goals and differential reproduction rates and indicate that the numbers of (especially male) surviving offspring and siblings are crucial to a man’s position in society.