Does observed fertility maximize fitness among New Mexican men?

Our objective is to test an optimality model of human fertility that specifies the behavioral requirements for fitness maximization in order (a) to determine whether current behavior does maximize fitness and, if not, (b) to use the specific nature of the behavioral deviations from fitness maximization towards the development of models of evolved proximate mechanisms that may have maximized fitness in the past but lead to deviations under present conditions. To test the model we use data from a representative sample of 7,107 men living in Albuquerque, New Mexico, between 1990 and 1993. The model we test proposes that low fertility in modern settings maximizes number of grandchildren as a result of a trade-off between parental fertility and next generation fertility. Results do not show the optimization, although the data do reveal a trade-off between parental fertility and offspring education and income. We propose that two characteristics of modern economies have led to a period of sustained fertility reduction and to a corresponding lack of association between income and fertility. The first is the direct link between costs of investment and wage rates due to the forces of supply and demand for labor in competitive economies. The second is the increasing emphasis on cumulative knowledge, skills, and technologies in the production of resources. Together they produce historically novel conditions. These two features of modern economies may interact with evolved psychological and physiological mechanisms governing fertility and parental investment to produce behavior that maximizes the economic productivity of lineages at the expense of fitness. If cognitive processes evolved to track diminishing returns to parental investment and if physiological processes evolved to regulate fertility in response to nutritional state and patterns of breast feeding, we might expect non-adaptive responses when returns from parental investment do not diminish until extremely high levels are reached. With high economic payoffs from parental investment, people have begun to exercise cognitive regulation of fertility through contraception and family planning practices. Those cognitive processes maynot have evolved to handle fitness trade-offs between fertility and parental investment. A preliminary presentation of this data was published in R. I. M. Dunbar, ed.,Human Reproduction Decisions: Biological and Social Perspectives. New York: St. Martin’s Press, 1995. Support for the research project, “Male Fertility and Parenting in New Mexico,” began with two seed grants from the University of New Mexico’s Biomedical Research Grants Program, 1988 and 1989, and one from the University of New Mexico Research Allocations Committee, 1988. Further seed money as well as interim funding came from the William T. Grant Foundation (#89130589 and #91130501). The major support for the project came from the National Science Foundation from 1990 to 1993 (#BNS-9011723 and #DBS-911552). Both National Science Foundation grants included Research Experience for Undergraduates supplements. Hillard S. Kaplan is an Associate Professor of Anthropology at the University of New Mexico. His earlier research and publications focused on food sharing, time allocation, parental investment, and reproductive strategies among Ache hunter-gatherers in Paraguay, Machiguenga and Piro forager-horticulturalists in Peru, and villagers of several ethnicities in Botswana. New research and theory concern fertility, parental investment, and mating strategies in developed and developing nations. This research formulates a new theory of reproductive decision-making and the demographic transition, integrating human capital and parental investment theory in a synthesis of economic and evolutionary approaches. Jane B. Lancaster is a Professor of Anthropology at the University of New Mexico. Her research and publications are on human reproductive biology and behavior, especially human parental investment; women’s reproductive biology of pregnancy, lactation, and child-spacing; and male fertility and investment in children. Current research with Hillard S. Kaplan is on male life history strategies among a large sample of men in New Mexico. She has coedited three books on human parental investment:School-Age Pregnancy and Parenthood (with B. Hamburg),Parenting across the Life Span (with J. Altmann, A. Rossi, and L. Sherrod), andOffspring Abuse and Neglect (with R. Gelles). She is scientific editor of a quarterly journal,Human Nature: An Interdisciplinary, Biosocial Perspective published by Aldine de Gruyter. She is also a council member of the newly formed Human Behavior and Evolution Society. John A. Bock is Andrew W. Mellon Post-Doctoral Fellow in Epidemiology and Population Health at the National Centre for Epidemiology and Population Health, The Australian National University. His research focuses on the allocation of parental investment and the determinants of children’s activities, integrating aspects of economic and evolutionary theory. He has ongoing field research with Bantu and Bushmen agro-pastoralists and forager-horticulturalists in the Okavango Delta, Botswana. He is also collaborating with Lancaster and Kaplan on the determinants of progeny distribution and homosexuality among New Mexican men. Sara E. Johnson is a Ph.D. candidate at the University of New Mexico. Her major research trajectory focuses on trade-offs in life history characters. Her research experience includes participation in a study of variation in growth and development among children in a multi-ethnic community in the Okavango Delta, Botswana, in addition to her dissertation work on individual variation in growth and mortality among juvenile baboons. She is collaborating with Lancaster and Kaplan on the association between survival and fertility among Albuquerque men.     

Studies on homoveratric acid transformation by the ligninolytic fungus Pleurotus eryngii

Homoveratric acid (HVA) degradation was observed in cultures of Pleurotus eryngii lacking lignin peroxidase (LiP) activity. Extracellular enzymes seemed responsible for this transformation, and the lack of activity after ultrafiltration of the culture liquid suggests that the presence of some low-molecular-size compounds is required. This hypothesis is supported by rapid HVA transformation after addition of the synthetic laccase substrate 2,2-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) to the ultrafiltered liquid. HVA transformation by the extracellular enzymes from P. eryngii takes place via C-C breakdown and formation of veratryl alcohol, which is further transformed into veratraldehyde. The same major compounds were found during HVA transformation by LiP from Phanerochaete chrysosporium, but this reaction was not stimulated by ABTS. Although the involvement of other enzymes cannot be ruled out, purified laccase from Pleurotus eryngii caused the same HVA transformation pattern in presence of ABTS. Moreover, veratryl alcohol oxidation by P. eryngii laccase was demonstrated in the presence of ABTS. These results suggest that enzymatic systems lacking LiP could be responsible for natural degradation of lignin.     

Continuous limonin degradation by immobilizedRhodococcus fascians cells in K-carrageenan

Limonin can be effectively degraded byRhodococcus fascians cells. These bacteria can be entraped in -carrageenan, and used in a continuous stirred tank reactor to degrade limonin in a continuous process. The effects of temperature limonin concentration, dilution rate, and aeration on the reactor behaviour have been tested, and the results correlated with changes in limonin conversion, substrate degradation rate, and free and immobilized biomass. Results showed that the immobilized cells were able to debitter limonin-containing media and the immobilized biomass was quite stable throughout the operational conditions tested. A population of free biomass was present in the reactor, the quantity of which was dependent on dilution rate. The immobilized bacteria increased its limonin-degrading capability when the substrate concentration was increased. The aeration was not strictly necessary for limonin degradation. Additionally, the immobilized cells were active and stable for more than 2 months of continuous operation, and were able to recover their limonin-degrading capability when used intermittently. Finally, none of the main components of a juice was noticeably altered during limonin degradation, so the reactor response was good enough to consider its application.     

Purification of amoebolytic substances from Bacillus licheniformis M-4

Three antibiotic peptides with amoebolytic activity have been purified from culture supernatants of Bacillus licheniformis M-4 (amoebicins m4-A, m4-B, and m4-C). They were hydrophilic peptides consisting of six different amino acids (Asp, Glu, Ser, Thr, Pro, Tyr). Their molecular weights ranged from 3,000 to 3,200. Purified amoebicins were active against human pathogenic and non-pathogenic strains of Naegleria. They also showed a broad antifungal spectrum, but a narrow antibacterial activity.Abbreviations (TFA) Trifluoroacetic acid     

Dendritic arbor alterations in the medial superior olivary neurons of neonatally underfed rats

Golgi-Cox-stained bipolar cells of the medial superior olive (MSO) were analyzed in control and undernourished Wistar strain rats at 12, 20, 30 and 40 days of age. Undernutrition significantly reduced the number of dendrites and the extension of ipsilateral dendritic prolongations, with no effects upon the cross-sectional somal area and minimal alterations in the corresponding contralateral dendritic branches. The data suggest that in underfed rate, afferents from the receptors projecting to the MSO via the anteroventral cochlear nuclei may cause an imblance in the binaural interactions which occur between the axon terminals and the ipsilateral contralateral dendritic arbors of MSO neurons.     

A population analysis of Robertsonian and Ag-NOR polymorphisms in brown trout (Salmo trutta)

An analysis of Robertsonian polymorphism and variation in the number of active NORs has been carried out in several populations of brown trout (Salmo trutta) from Northwestern Spain. The karyotype of this species appears to be soundly established, and essentially no variation has been found in chromosome number. Interindividual and interpopulation variation in arm number was detected, with figures ranging between 100 and 102 among individuals, and between 100.10 and 100.80 among populations. This variation in arm number is solely attributable to the polymorphism of the short arm of the main NOR-bearing pair 11, which can appear from acrocentric to metacentric in different individuals. Most populations analyzed showed the standard distribution of active NORs previously observed in this species. The Miño drainage basin, and specially the Chamoso population, showed a multi-chromosomal distribution of active NORs, with several new locations, always telomeric. In most cases no concordance was observed between previously detected rDNA sites in S. trutta and the new Ag-NOR locations. This fact suggests a transposition mechanism rather than an activation of silent rDNA sites to explain this multichromosomal NOR pattern.     

Two related low-temperature-inducible genes of Arabidopsis encode proteins showing high homology to 14-3-3 proteins,a family of putative kinase regulators

We have isolated two Rare Cold-Inducible (RCI1 and RCI2) cDNAs by screening a cDNA library prepared from cold-acclimated etiolated seedlings of Arabidopsis thaliana with a subtracted probe. RNA-blot hybridizations revealed that the expression of both RCI1 and RCI2 genes is induced by low temperature independently of the plant organ or the developmental stage considered. However, RCI1 mRNA accumulates faster and at higher levels than the RCI2 one indicating that these genes have differential responsiveness to cold stress. Additionally, when plants are returned to room temperature, RCI1 mRNA decreases faster than RCI2. In contrast to most of the cold-inducible plant genes characterized, the expression of RCI1 and RCI2 is not induced by ABA or water stress. The nucleotide sequences of RCI1 and RCI2 cDNAs predict two acidic polypeptides of 255 and 251 amino acids with molecular weights of 29 and 28 kDa respectively. The alignment of these polypeptides indicates that they have 181 identical amino acids suggesting that the corresponding genes have a common origin. Sequence comparisons reveal no similarities between the RCI proteins and any other cold-regulated plant protein so far described. Instead, they demonstrate that the RCI proteins are highly homologous to a family of proteins, known as 14-3-3 proteins, which are thought to be involved in the regulation of multifunctional protein kinases.     

Sucrose transport and hydrolysis inRhizobium tropici

TheRhizobium tropici strain CFN 299 was maintained on PY medium and was grown in minimal medium (MM) with sucrose, glucose, fructose and glutamate (or their combination) as carbon sources. Bacteria were able to simultaneously use different carbon sources and, with a combination sucrose and glutamate, the growth rate was faster than with either carbon source alone. Sucrose transport was induced by sucrose and partially repressed by glucose and glutamate if they were included in MM as additional carbon sources. The transport of sucrose was active because both an uncoupler (dinitrophenol, DNP) and inhibitors of terminal oxidation (KCN, NaN₃) severely reduced sucrose uptake. Sucrose transport was also sensitive to a functional sulfhydryl reagent but was much less sensitive to EDTA and arsenate. We obtained nonlinear Lineweaver-Burk plots for the uptake of sucrose (by sucrose-grown bacteria), and this implied the existence of at least two uptake mechanisms. Invertase (EC 3.2.1.26) is the main enzyme for sucrose hydrolysis in this organism. This enzyme was induced by sucrose and had high activity in mid-log phase cells when sucrose was the sole carbon source (0.2%). Invertase activity was not detected in growth medium. In general, the results obtained support the idea, thatR. tropici is adapted to sucrose utilization and to multicarbon nutrition during its interaction with plants.     

Phytochrome-mediated effects on extracellular peroxidase activity, lignin content and bending resistance in etiolated Vicia faba epicotyls

Etiolated Vicia faba seedlings were exposed to continuous red light to investigate whether changes in extracellular peroxidase activity were correlated in time and localization with changes in extension growth and/or lignin content in the subapical region of the epicotyl. Continuous red light: (a) increased extracellular peroxidase activity after a lag of ca 0.5 h, followed by a maximum peak after 2.5 h due to slightly acidic isoforms (pI = 6–6.5, according to isoelectrofocusing gels), a minimum after 4 h and a second maximum after 8 h due to acidic isoforms (pI=4–5), (b) increased lignin content and epicotyl resistance to bending after a lag of ca 4 h, i.e. simultaneously with changes in acidic extracellular peroxidase activity, and (c) reduced extension growth to a stable rate after a lag of ca 1 h, not coinciding with the kinetics of any of the extracellular peroxidase isoforms. These effects of continuous red light were at least partially mediated by phytochrome. Tissue printing and anatomical studies revealed red light effects on extracellular peroxidase activity and lignin content mainly in the outer cortical parenchyma. The results are consistent with the involvement of phyto-chrome-mediated effects on extracellular peroxidases (acidic isoforms) in the transduction chain leading to lignin responses to red light.     

The making of the minibody: An engineered β-protein for the display of conformationally constrained peptides

Conformationally constraining selectable peptides onto a suitable scaffold that enables their conformation to be predicted or readily determined by experimental techniques would considerably boost drug discovery process by reducing the gap between the discovery of a peptide lead and the design of a peptidomimetic with a more desirable pharmacological profile. With this in mind, we designed the minibody, a 61-residue β-protein aimed at retaining some desirable features of immunogloblin variable domains, such as tolerance to sequence variability in selected regions of the protein and predictability of main chain conformation of the same regions, based on the ‘canonical structures’ model. To test the ability of the minibody scaffold to support functional sites we also designed a metal binding version of the protein by suitably choosing the sequences of its loops. The minibody was produced both by chemical syntyhesis and expression in E. coli and charactgerized by size exclusion chromatography, UV CD (circular dichroism) spectroscopy and metal binding activity. All our data supported the model, but a more detailed structural characterization of the molecule was impaired by its low soubility. We were able to overcome this problem both by further; mutagenesis of the framework and by addition of a solublizing motif. The minibody is being used to select constrained human IL-6 peptidic ligands from a library displayed on the surface of the f1 bacteriophage.