Modern human origins in Australasia: Replacement or evolution?

The controversies surrounding the origins of modern humans have spawned two competing hypotheses, namely Replacement and Multiregional Evolution. The first suggests that modern Homo sapiens evolved first in Africa, as late as 140 ka, and subsequently inhabited the balance of the Old World. Conversely, the second hypothesis posits that modern humans evolved principally from local populations of archaic hominids indigenous to the major regions of the Old World. The hominid mandibular remains (ca. 1 Ma) from Sangiran, central Java, Indonesia, were studied in order to test these hypotheses. Non-metric comparisons were performed between these fossils and aboriginal H. sapiens from Africa and Australia. The Replacement model would be supported by a unique Afro-Australian grouping while Multiregional Evolution would be suggested by a Sangiran-Australasian group which would exclude the modern Africans. These data support the Multiregional Evolution hypothesis in that a plurality (eight) of the seventeen non-metric features link Sangiran to modern Australians, while only three exclusively group the humans from Africa and Australia. These results are suggestive of morphological continuity, which implies the presence of a genetic continuum in Australasia dating back at least one million years.     

Out of Africa? What do genes tell us?

Genetic diversity patterns in nuclear versus mitochondrial systems and in low versus high mutation rate systems do not support the hypothesis of a recent African origin for all of humanity following a split between Africans and non-Africans 100,000 years ago, nor do genetic distance data. Geographical analyses of nuclear and mitochondrial gene trees do not support the hypothesis of a recent global replacement of humans coming out of Africa, although a local replacement event in Europe is indicated by these analyses and recent studies on Neandertal DNA. The gene tree analyses instead indicate that genetic interchanges have ensured that all of humanity has evolved as a single evolutionary lineage with no major splits.     

Interaction of human Waldenstr?m's IgM proteins with guinea pig and human complement.

The activity of purified human Waldenstr?m's IgM protein to fix complement of human and guinea pig origins was compared at different temperatures using the polystyrene latex particle-adsorption method. It was shown that the interaction of the IgM proteins with complement differed depending on the source of complement and that a pronounced heterogeneity in complement-fixing activity was observed among the IgM proteins when tested with guinea pig complement. Thus, by the use of guinea pig complement, six human IgM proteins examined were classified roughly into two groups, one having a high and the other a low activity at 3 C as well as at 37 degrees C. With human complement, five proteins showed a rather uniform activity at 37 degrees C. However, there was one protein with no detectable activity, suggesting the presence of non-complement-fixing protein in the IgM class. All the six proteins showed no significant activity with human complement at 3 C. No antigenic difference has been found as yet in the Fc or Cmu2 region among these IgM proteins examined.     

H3Africa: An Africa exemplar? Exploring its framework on protecting human research participants

The Human Heredity and Health in Africa (H3Africa) Consortium is a conglomeration of research and infrastructure projects spread throughout Africa whose aim is to apply genomic methodology to diseases affecting the people in the region. Its operation is innovative in the sense that it is doing something new; that is, filling a hitherto existing void in genomic research capability of African scientists and infusing resources and manpower to institutions and investigators across Africa. But aside from developing and sustaining capacity in genomic research and biorepositories, H3Africa is also invested in developing appropriate ethical regulatory regime to govern research in these areas. This latter concern –research ethics governance – is the major subject of this paper. Specifically, the paper discusses protection of research participants as envisaged by H3Africa in the area of consent, safeguarding privacy, maintaining confidentiality of health information and sharing of data/biospecimens. The ultimate goal is to determine whether H3Africa initiatives and processes are consistent or at odds with international guidelines and best practices.     

Taste: independent origins of chemoreception coding systems?

A large family of divergent candidate gustatory receptors has been identified in Drosophila. As with the odorant receptors, one receptor is expressed per sensory neuron, each class of which projects to discrete regions of the brain, allowing a combinatorial coding system for specific recognition of ligands.     

Unsegmented annelids? Possible origins of four lophotrochozoan worm taxa

In traditional classification schemes, the Annelida consists of the Polychaeta and the Clitellata (the latter including the Oligochaeta and Hirudinida). However, recent analyses suggest that annelids are much more diverse than traditionally believed, and that polychaetes are paraphyletic. Specifically, some lesser-known taxa (previously regarded as separate phyla) appear to fall within the annelid radiation. Abundant molecular, developmental, and morphological data show that the Siboglinidae, which includes the formerly recognized Pogonophora and Vestimentifera, are derived annelids; recent data from the Elongation Factor-1α (EF-1α) gene also suggest that echiurids are of annelid ancestry. Further, the phylogenetic origins of two other lesser-known groups of marine worms, the Myzostomida and Sipuncula, have recently been called into question. Whereas some authors advocate annelid affinities, others argue that these taxa do not fall within the annelid radiation. With advances in our understanding of annelid phylogeny, our perceptions of body plan evolution within the Metazoa are changing. The evolution of segmentation probably is more plastic than traditionally believed. However, as our understanding of organismal evolution is being revised, we are also forced to reconsider the specific characters being examined. Should segmentation be considered a developmental process or an ontological endpoint?     

Mitochondria: One of the origins for autophagosomal membranes?

Macroautophagy is a transport pathway to the lysosome/vacuole that contributes to the degradation of numerous intracellular components. Despite the recent advances achieved in the understanding of the molecular mechanism underlying macroautophagy, the membrane origin of autophagosomes, the hallmark of this process is still a mystery. It has been suggested that mitochondria may be one of the lipid sources for autophagosome formation and that possibly this organelle provides the phosphatidylethanolamine (PE) that covalently links to the members of the ubiquitin-like Atg8/microtubule-associated protein 1 light chain 3 (LC3) protein family. These lipidated proteins are inserted into the outer and inner surface of autophagosomes and are essential for the biogenesis of these large double-membrane vesicles. However, because PE is an integral component of all cellular membranes, designing appropriate experiments to determine the origin of the autophagosomal PE is not easy. In this review, we discuss the idea that mitochondria provide the pool of PE necessary for the autophagosome biogenesis and we propose some possible experimental approaches aimed to explore this possibility.     

Physical enhancement of human performance: Is law keeping pace with science?

In the area of genometry—the nascent field of science and technology that proposes to apply enhanced understanding of the human genetic code to reshaping our individual and collective destinies—no topic has generated more interest among the general public, as well as in the athletic community, than the potential for physical enhancement of the human body and its performance. Genometric experiments have produced physically enhanced mice, and the production of similarly enhanced humans may not be far off. Although it is not the objective of most genometric research, the day will come when gene-based “treatments” will enable individuals to build muscle or increase endurance faster than is possible through conventional methods. This article describes developments in the area of physical enhancement that may find application in the “gene doping” of athletes. For example, human performance-related genes may be delivered to athletes using tools developed for research in gene therapy; the protein products of these genes may be administered in recombinant form; and recently discovered small-molecule activators of the major genetic regulatory pathways of physical prowess may be taken orally, providing “exercise in a pill”. This article also describes US and international attempts to regulate and punish the use of prohibited techniques for performance enhancement among athletes. As science advances, defining and detecting “gene doping” becomes increasingly complex. Thus, the study of physical enhancement provides an ideal starting point for the interdisciplinary Redefined Destinies Colloquium's examination of the intersection between law and science.     

Elimination of onchocerciasis from Africa: possible?

Human onchocerciasis, a parasitic disease found in 28 African countries, six Latin American countries and Yemen, causes blindness and severe dermatological problems. In 1987, efforts to control this infection shifted from vector approaches to include the mass distribution of ivermectin - a drug donated by Merck & Co. for disease control in Africa and for disease elimination in the Americas. Currently, almost 25 years later, with the Americas being highly successful and now approaching elimination, new evidence points towards the possibility of successful elimination in Africa. We suggest several major changes in the programmatic approach that through focused goal-directed effort could achieve global elimination of onchocerciasis by 2025.     

Confirmation of assignment of the human α1-crystallin gene (CRYA1) to chromosome 21 with regional localization to q22.3

Summary The crystallins are highly conserved structural proteins universally found in the eye lens of all vertebrate species. In mammals, three immunologically distinct classes are present, -, -, and -crystallins, and each class represents a multigene family. The -crystallin gene family consists of 1-crystallin (CRYA1) and 2-crystallin (CRYA2) genes (previously designated A-and B-crystallin, respectively), which show extensive sequence homology. We constructed a synthetic oligonucleotide probe of 25 bases corresponding to a specific region of the human 1-crystallin gene sequence. This 25-mer probe bears little sequence homology to human 2-crystallin gene and does not cross-hybridize to 2-crystallin sequences in Southern blot analysis. Using this unique synthetic probe, we have demonstrated the identity of the 1-crystallin gene in human genomic DNA. In addition, we have also confirmed its chromosomal location on human chromosome 21. Finally, we have regionally localized the gene to q22.3 by using both Southern blot analysis of a panel of cell hybrids containing different parts of human chromosome 21, and in situ hybridization to metaphase chromosomes. The use of synthetic oligonucleotide probes specific for individual genes should be useful in identifying and mapping members of multigene families.