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PubMed2003

Evolution of the deep-sea gulper eel mitochondrial genomes: large-scale gene rearrangements originated within the eels.

Recent studies have demonstrated that deviations from the typical vertebrate mitochondrial gene order are more frequent than initially thought. Such deviations, however, are minor, with inversions and/or translocations of a few genes being involved and tandem duplication of the gene regions followed by deletions of genes having been invoked as mechanisms originating in such novel gene order. During the course of molecular phylogenetic studies on the Elopomorpha (eels and their allies), we found that mitochondrial genomes (mitogenomes) from the two deep-sea gulper eels, Eurypharynx pelecanoides (Eurypharyngidae) and Saccopharynx lavenbergi (Saccopharyngidae), exhibit an identical gene order which greatly differs from that of any other vertebrates. Phylogenetic analysis using the mitogenomic data from 59 species of fish not only confirmed a single origin of such a gene order with confidence but also indicated that it had been derived from the typical vertebrate gene order. Detailed comparisons of the gulper eel gene order with that of typical vertebrates suggested that occurrence of a single step, large-scale duplication of gene region extending >12 kb, followed by deletions of genes in a common ancestor of the two species, most parsimoniously accounts for this unusual gene arrangement.

Animals↗

PubMed2001

Tripedal knuckle-walking: a proposal for the evolution of human locomotion and handedness.

A comparative morphological analysis of human and non-human hominoids was conducted in an attempt to determine the mode of locomotion of the protohominid. Although the generalized hominoid anatomy permits variation of locomotion: brachiation, knuckle-walking, etc., minor variations in structure determine which behavior is favored. Arboreal arm swinging requires a flexible forelimb while terrestrial fist or knuckle-walking demands more rigidity of the hand and wrist. It is demonstrated that the large human thumb accompanied by the strong adduction of the thenar, hypothenar, and palmar interosseous muscles offer powerful rigidity to the hand, while fusion of the os centrale with the scaphoid during gestation permits the formation of an arch of carpals which imbue the wrist with the stability necessary for weight bearing. Fascialization of the contrahentes and dorsiepitrochlearis muscles in the human as well as depilation of the middle phalanges; the webbing (syndactyly) of the palm; the direction of the fibers of the interosseous membrane of the forearm; the shape of the puerile annular ligament, and the direction of the human glenoid fossa strongly suggest that the ancestor of man used a knuckle-walking form of locomotion prior to becoming bipedal. A model is presented that suggests that bipedalism was attained through an intermediate stage of tripedalism. The model is based on the fact that man's anatomy is much more asymmetric than that of the great apes. A presumption is made that due to the absence of trees for climbing in the transition from forest to open plain, the protohominid needed to carry tools (stones) at all times for protection. Stones could be carried for long distances on the posterior iliac crest since the weight would be shifted posteriorly over the legs. Pick up, medial rotation and adduction of the stone would employ a two-muscle chain of biceps brachii and latissimus dorsi. On the iliac crest, the stone is posterior to the coronal plane of the glenohumeral joint, and with the contraction of this two-muscle chain, the shoulder on one side is moved posteriorly effecting a semi-erect posture. It is proposed that tripedalism of the protohominid may be an explanation for the handedness unique to hominids.

Animals↗

PubMed1982

Comparison of the nucleotide sequence of cloned human and guinea-pig pre-alpha-lactalbumin cDNA with that of chick pre-lysozyme cDNA suggests evolution from a common ancestral gene.

Nucleotide sequence analyses of essentially full-length copies of human and guinea-pig pre-alpha-lactalbumin cDNAs contained within recombinant plasmids, (i) confirm the presence of 19 amino acid hydrophobic amino terminal peptide extensions encoded within each mRNA; and (ii) provides evidence for the existence of a minor variant of guinea-pig alpha-lactalbumin mRNA encoding a protein with a 36 residue carboxyl-terminal extension. Comparison of the nucleotide sequence within the coding region of the human, and the predominant guinea-pig pre-alpha-lactalbumin mRNAs, with the analogous region of hen pre-lysozyme mRNA provides compelling evidence that all have evolved from a common ancestral gene.

Amino Acid Sequence↗

PubMedDate not supplied

Allele and genotype frequencies of polymorphic FMO3 gene in two genetically distinct populations.

The aims of this study were to analyze flavin-containing monooxygenase 3 (FMO3) polymorphisms and allele and genotype frequencies in 256 Han Chinese and 50 African-American individuals, to compare the allele and genotype frequencies of these populations with those of other world populations. For Han Chinese, genotyping of three common single nucleotide polymorphisms, E158K, V257M and E308G was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). For African-Americans, genotyping of all coding exons was performed by modified PCR-single strand conformational polymorphism (SSCP). Evolutionary rates of FMO3 were estimated computationally. We found that there were significant differences in allele and genotype frequencies among Han Chinese, African-Americans and other world populations. In Han Chinese, the minor allele frequencies (MAFs) were 0.229 (E158K), 0.203 (V257M) and 0.148 (E308G), respectively. In African-Americans, MAFs were 0.48 (E158K), 0.05 (V257M) and 0 (E308G), respectively. There was rapid evolution during the divergence of primate FMO3. This is the first report comparing FMO alleles and genotypes between Han Chinese and African-Americans. A Han Chinese population database has been established for three gene polymorphisms. The data presented here justify further pharmacogenetic studies for potentially optimizing recommended drug dosages and evaluating relationships with disease processes.

Adult↗

PubMed2004

Analysis of factors shaping codon usage in the mitochondrion genome of Oryza sativa.

In this paper, the main factors shaping codon usage in the mitochondrion genome of rice were reported. Correspondence analysis, a commonly used multivariate statistical approach, was carried out to analyze synonymous codon usage bias. The results showed that the main trend was strongly correlated with the gene expression level assessed by the 'Codon Adaptation Index' value, a result that was confirmed by the distribution of genes along the first axis. From the results that there were two significant correlations between axis 1 coordinates and the GC, GC3s content at silent sites of each sequence, and clearly significant correlations between the 'Effective Number of Codons' values and GC, GC3s content, we inferred that codon usage bias was affected by gene nucleotide composition also. In addition, the hydrophobicity of each protein also played some roles in shaping codon usage in this organelle, which could be confirmed by the significant correlation between the positions of genes placed on the first axis and the hydrophobicity value of each protein. In summary, natural selection played a crucial role, nucleotide mutational bias and amino acid composition only in a minor way, in shaping codon usage in the mitochondrion genome of rice. Notably, 21 codons defined firstly as 'optimal codons' might provide some more useful information for gene engineering and/or evolution studying.

Journal Article↗

PubMed1999

Natural evolution of skin test sensitivity in patients allergic to beta-lactam antibiotics.

BACKGROUND: Subjects with immediate reactions to penicillins and positive skin test responses may lose sensitivity if penicillin is avoided. The longer the interval between the reaction and the skin test, the greater the likelihood of having a negative result. OBJECTIVE: We sought to study prospectively the evolution of skin test sensitivity in a group of subjects allergic to penicillin with positive skin test responses to different penicillin determinants. METHODS: Skin tests were performed with major and minor determinants of benzylpenicillin (BPO/MDM), amoxicillin (AX), and ampicillin at the initial evaluation and repeated 1, 3, and 5 years later if the responses were still positive. Subjects were divided into 2 groups. Group A consisted of patients with a positive skin test response to benzylpenicilloyl or minor determinant mixture, and group B consisted of those with a selective response to amoxicillin and good tolerance to benzylpenicillin. RESULTS: In group A (n = 31) after 1 year, 25 patients continued to have positive responses and 6 began to have negative responses; after 3 years, 18 continued to have positive responses, 5 began to have negative responses, and 2 were lost to follow-up; and after 5 years, 12 continued to have positive responses, 5 began to have negative responses, and 1 was lost to follow-up. In group B (n = 24) 12 had positive responses, and 12 had negative responses after 1 year; 6 had positive responses, 5 had negative responses, and 1 was lost to follow-up after 3 years; and no patients had positive responses, 5 had negative responses, and 1 was lost to follow-up after 5 years. Survival analysis showed significant differences between groups (log-rank test = 12.8; P <. 0003). CONCLUSION: Patients with a selective response to amoxicillin tended to lose sensitivity faster than those who responded to several penicillin determinants, supporting the existence of at least 2 distinct types of IgE response in patients allergic to beta-lactam.

Adult↗

PubMed2001

Longitudinal evaluation of cognitive disorder in Huntington's disease.

The study investigated longitudinal change in cognitive function in 87 patients with Huntington's disease (HD), using a range of neuropsychological tests, which tap mental manipulative abilities, memory, and frontal executive skills. Over a 1-year period the largest changes were noted in letter fluency, object recall, and Stroop Test performance, whereas no changes were noted over more than 3 years on the modified Wisconsin Card Sorting Test. Contrary to expectation, greater change was evident over 1 year for tasks with low compared to high cognitive demands. The differential sensitivity of tasks was attributed in part to inherent characteristics of the tests themselves: their capacity to detect minor gradations of change and their vulnerability to practice effects. However, the greater change for relatively automatic, speed-based tasks with low cognitive demands was interpreted as reflecting the evolution of HD, with a greater magnitude of change occurring in basal ganglia than cortical function. One purpose of the study was to identify tasks sensitive to the progression of HD and hence most suitable for the evaluation of therapies. Despite reaching statistical significance by virtue of the large group size, numerical differences in test scores over 1 year were very small, suggesting that the use of such tests to evaluate change in individuals or small groups of subjects would be problematic. The data highlight the slow progression of HD, the limitations of standard cognitive tests in detecting change over short periods, and the need for therapeutic studies that encompass a relatively prolonged time frame.

Adult↗

PubMed2005

The U11/U12 snRNP 65K protein acts as a molecular bridge, binding the U12 snRNA and U11-59K protein.

U11 and U12 interact cooperatively with the 5' splice site and branch site of pre-mRNA as a stable preformed di-snRNP complex, thereby bridging the 5' and 3' ends of the intron within the U12-dependent prespliceosome. To identify proteins contributing to di-snRNP formation and intron bridging, we investigated protein-protein and protein-RNA interactions between components of the U11/U12 snRNP. We demonstrate that the U11/U12-65K protein possesses dual binding activity, interacting directly with U12 snRNA via its C-terminal RRM and the U11-associated 59K protein via its N-terminal half. We provide evidence that, in contrast to the previously published U12 snRNA secondary structure model, the 3' half of U12 forms an extended stem-loop with a highly conserved seven-nucleotide loop and that the latter serves as the 65K binding site. Addition of an oligonucleotide comprising the 65K binding site to an in vitro splicing reaction inhibited U12-dependent, but not U2-dependent, pre-mRNA splicing. Taken together, these data suggest that U11/U12-65K and U11-59K contribute to di-snRNP formation and intron bridging in the minor prespliceosome.

Amino Acid Motifs↗

PubMed2000

Correlation between testicular biopsies (prepubertal and postpubertal) and spermiogram in cryptorchid men.

Twenty-one young men who underwent testicular biopsy and orchidopexy in infancy consulted owing to infertility and had biopsies again. The first and second biopsy specimens from these patients were compared by means of a semiquantitative study of the seminiferous tubules to evaluate the evolution of germ cells and to correlate these data with spermatozoon numbers. The infant testes showing lesions were classified into 3 types according to the mean tubular diameter and tubular fertility index: (1) slight lesions, (2) marked germinal hypoplasia, and (3) severe germinal hypoplasia. In the adult testes, spermatogenesis was evaluated by calculating the average numbers of spermatogonia, primary spermatocytes, young spermatids, and mature spermatids. These testes were classified as (1) normal; (2) having lesions in the adluminal compartment; (3) having lesions in the basal compartment; and (4) mixed atrophy. The number of differentiated spermatids was correlated with the expected number of spermatozoa in the ejaculate by a power regression curve. The observation of certain histologic lesions in the seminiferous tubules was assumed to indicate excretory duct obstruction: ectasia, indented outline of the seminiferous epithelium, intratesticular spermatocele, apical cytoplasmic vacuolation of Sertoli cells, and mosaic distribution of testicular lesions. There was a correlation between the prepubertal lesions and the degree of spermatogenesis in postpubertal biopsy specimens. The evolution of the 40 testes without regard to their location in infancy (cryptorchid or scrotal) was as follows. The 14 infant testes with a normal histologic pattern (5 testes) or minor lesions (9 testes) evolved to testes with lesions of the adluminal compartment (8 testes), mixed atrophy (4 testes), or lesions of the basal and adluminal compartments (2 testes). The 6 testes with marked germinal hypoplasia evolved to testes with mixed atrophy. The 20 testes with severe germinal hypoplasia evolved to testes with mixed atrophy (17 testes), Sertoli-cell-only tubules (2 testes), or lesions in the basal compartment (1 testis). In the 9 patients with a histologic pattern of obstruction bilaterally (6 men) or unilaterally (3 men), the expected number of spermatozoa according to the correlation curve was much higher than the actual number in the spermiogram. This means that the testes of many azoospermic men produce spermatozoa, and this finding corroborates the importance of testicular biopsy in infertility studies.

Adult↗

PubMed1993

Human T cells respond to mouse mammary tumor virus-encoded superantigen: V beta restriction and conserved evolutionary features.

Mouse mammary tumor virus (MMTV)-encoded superantigens (SAGs) influence the murine T cell repertoire and stimulate a strong mixed lymphocyte response in vitro. These SAGs are encoded by the open reading frame of the 3' long terminal repeat of MMTV, termed MMTV SAGs. The T cell response to MMTV SAGs is V beta restricted and requires expression of the class II molecules of the major histocompatibility complex (MHC) on the presenting cells. While human T cells respond to bacterial SAGs, it is not known if human T cells or human MHC class II molecules can interact with MMTV SAGs. A fibroblastic cell line expressing the human MHC class II molecule HLA-DR1 and the Mtv-7 sag gene encoding Mls-1 was used to stimulate human T cells. We show here that human T cells efficiently proliferate in response to Mls-1 presented by HLA-DR1. This T cell response was inhibited by mAbs directed against CD4 or MHC class II molecules but not by mAbs specific for CD8 or MHC class I molecules. Moreover, the response to Mls-1 was limited to human T cells expressing a restricted set of T cell receptor V beta chains. Human T cells expressing V beta 12, 13, 14, 15, and 23 were selectively amplified after Mtv-7 sag stimulation. Interestingly, these human V beta s share the highest degree of homology with the mouse V beta s interacting with Mls-1. These results show a strong evolutionary conservation of the structures required for the presentation and the response to retrovirally encoded endogenous SAGs, raising the possibility that similar elements operate in humans to shape the T cell repertoire.

Animals↗

PubMed2005

Bacterial plurality as a general mechanism driving persistence in chronic infections.

Classical methods for the study of bacterial pathogens have proven to be inadequate to inform with respect to chronic infections including those associated with arthroplasties. Modern methods of analysis have demonstrated that bacterial growth patterns, ecology, and intra-species heterogeneity are more complex than were envisioned by early microbiologists. Cultural methods were developed to study acute, epidemic infections, but it is now recognized that the phenotype associated with these diseases represents only a minor aspect of the bacterial life cycle, which consists of planktonic, attachment, biofilm, and dispersal phases. Over 99% of bacteria in natural populations are found in biofilms which contain multiple ecological niches and numerous phenotypes. Unfortunately, the effort to develop antibiotics has been directed solely at the planktonic minority (associated with systemic illness) which explains our inability to eradicate chronic infections. In this study we establish a new rubric, bacterial plurality, for the understanding of bacterial ecology and evolution with respect to chronic infection. The fundamental tenets of bacterial plurality are that the bacteria within an infecting population display multiple phenotypes and possess multiple genotypes. Phenotypic plurality is embodied in the biofilm paradigm and genotypic plurality is embodied in the concepts of the supra-genome and the distributed genome hypothesis. It is now clear that bacterial diversity provides bacterial populations, as a whole, the ability to persist in the face of a multi-faceted host response.

Bacterial Infections↗

PubMed1968

Does ethylene mediate root growth inhibition by indole-3-acetic Acid?

The effects of ethylene and of indole-3-acetic acid (IAA) on growth of excised pea root sections have been compared under a variety of conditions. After 16 hours treatment the inhibitory action of IAA is fully reversible on transfer of the root sections to IAA-free solutions. In contrast, inhibition by ethylene is almost totally irreversible. IAA inhibits growth from zero time; ethylene is generally without effect during the first 3 to 6 hours. The inhibitory action of ethylene is dependent on factors such as tissue age and solution composition which have no major effect on IAA inhibition. Ethylene production is enhanced by 100 mum IAA, but conditions which reduce the rate of ethylene evolution 2 to 3-fold at the same IAA concentration fail to affect the inhibitory action of IAA on elongation. It seems unlikely that ethylene can play more than a minor role in mediating inhibition of pea root growth by IAA.

Journal Article↗

PubMed2005

Chronic daily headache in children and adolescents: a clinic based study from India.

Chronic Daily Headache (CDH) is uncommon in Indian children compared to their adult counterpart. This is a retrospective study looking at the headache phenomenology of CDH in Indian children and adolescents. The validity of the case definitions of subtypes of chronic primary headaches mentioned in the IHS 2004 classification have been evaluated. 22 children (age range 8-15 years; M : F-16 : 6) diagnosed as having primary CDH using a modified definition seen between 2002 and 2003 have been studied. CDH has been defined as daily or near daily headaches > 15d/month for > 6 weeks. The rationale for this modified definition has been discussed. Majority of children (15/22) had a more or loss specified time of onset of regular headache spells resembling New Daily Persistent Headache (NDPH) but did not fulfil totally the diagnostic criteria of NDPH as laid down by IHS 2004. In all cases headache phenomenology included a significant vascular component. Headache phenomenology closely resembled Chronic Tension Type Headache (CTTH) in 4 patients and Chronic Migraine in 3 patients. However, in no patient in these groups, a history of evolution from the episodic forms of the diseases could be elicited. Heightened level of anxiety mostly related to academic stress and achievement was noted in the majority (19/22). Only a minority of patients (3/22) had anxiety and depression related to interpersonal relationships in the family. Medication overuse was not implicated in any patient. CDH in children in India is very much different from CDH in adults with the vast majority of patients exhibiting overlapping features of migraine and tension-type headache. There is need for a modified diagnostic criteria and terminology for chronic primary headaches in children.

Adolescent↗

PubMed2002

Characterization of CHAT and Cox type 1 live-attenuated poliovirus vaccine strains.

CHAT and Cox type 1 live-attenuated poliovirus strains were developed in the 1950s to be used as vaccines for humans. This paper describes their characterization with respect to virulence, sensitivity for growth at high temperatures, and complete nucleotide and amino acid sequences. The results are compared to those for their common parental wild virus, the Mahoney strain, and to those for two other poliovirus strains derived from Mahoney, the Sabin 1 vaccine strain and the mouse-adapted LS-a virus. Analysis of four isolates from cases of vaccine-associated paralytic poliomyelitis related to the CHAT vaccine revealed genetic and phenotypic properties of the CHAT strain following replication in the human gut. CHAT-VAPP strain 134 contained a genome highly evolved from that of CHAT (1.1% nucleotide differences), suggesting long-term circulation of a vaccine-derived strain in the human population. The molecular mechanisms of attenuation and evolution of poliovirus in humans are discussed in the context of the global polio eradication initiative.

3C Viral Proteases↗

PubMedDate not supplied

A brief review of formaldehyde carcinogenesis in relation to rat nasal pathology and human health risk assessment.

The 1980 report that inhaled formaldehyde induced nasal squamous cell carcinomas in rats had a significant societal impact and resulted in extensive research in the fields of rodent nasal pathology and human cancer risk assessment. This article presents an overview of the evolution of these events. It is concluded that the nasal passages of humans and rats are fundamentally identical biological target organs. Nevertheless, in the case of human health risk assessment, minor differences between these species may be critically important. Special attention should be paid to interspecies differences in nasal dosimetry and local metabolism; thus, chemical toxicity data derived from rats require careful interpretation when used for human risk assessments. In the case of formaldehyde, it is recommended that low-concentration (< or = 2 ppm airborne exposure) extrapolation, where no tissue damage is observed, be uncoupled from the responses at high concentrations (> or = 6 ppm), where epithelial degeneration, regenerative cell replication, and inflammation appear to be essential driving forces in formaldehyde carcinogenesis. The presence of treatment-related nasal lesions in rats following exposure to chemicals should always be treated as an indication of a potential human health risk, whether exposure is by the inhalation, oral, or dermal route.

Animals↗

PubMed2000

The malaria cauldron of Southeast Asia: conflicting strategies of contiguous nation states.

The past half-century or so has witnessed dramatic failures but also some successes in control of malaria in the world at large. South and Southeast Asia have had their share of both outcomes, a scenario that reflects many variables in control programs: technology, management strategy, human and financial resources. However, at least equally culpable have been major wars and minor conflicts, economic growth and stagnation, inequity of opportunity, urbanisation, deforestation, changing transport and communications. The history of malaria is thus an integral part of the broader political and economic evolution of the region, as well as the story of the wisdom and unwisdom of malaria specialists. In positive reflection on the latter, systematic organisational effort using standard tools of trade has seen the gradual elimination of major malaria foci from central plain regions of a number of nations in this large region, with residual foci at forested border areas. In many cases there is good evidence of sustainability of elimination in defined areas but the differing success stories reflect in part conflicting strategies in neighboring nation states. On the other hand, physical conflicts, population migration, inequitable economic change, border instability and many other socio-economic variables can be clearly seen to undermine the most ingenuous strategies. Undoubtedly the single most important negative ingredient is the rise and spread of multi-drug resistant falciparum malaria that has its epicenter in Southeast Asia, from which it threatens the world in insidious fashion. Containment of this phenomenon has been the focus of attention for 30 years, more particularly the past decade, and represents the greatest challenge at this time in predicting the continuing impact of malaria globally on human history. So too does the compelling necessity to link malaria control with macro and micro economic planning. This challenge impinges on the sovereignty of individual nations in this region, for they exist in contiguity, so that successful applications of technology require collaborative political determination.

Animals↗

PubMed1991

Patterns of antigenic expression of human glioma cells.

Gliomas are known to express over a hundred antigens, and no doubt make many more unknown antigens. Major categories of glioma cell antigens include glial antigens, ECM antigens, muscle antigens, melanoma antigens, "tumor-specific" antigens, and cellular proliferation antigens. A strikingly low number of cultured gliomas express glial antigens. They commonly express not only ectodermal, but also mesenchymal ECM antigens. Tumor-specific antigens have been an elusive goal of neuro-oncologists, but there are bright new prospects in need of further study. These include direct screening of hybridoma supernatants on glioma tissue and targeting glycolipids, glycoproteins, and oncogene products. Cellular proliferation antigens will become increasingly important in predicting prognosis of gliomas. Proliferation antigens of cultured gliomas are under intense scrutiny at present. The extent and evolution of antigenic heterogeneity of neoplastic cells in gliomas raise basic biologic questions with profound clinical ramifications. Individual glioma cell lines may generate more than 30 subtypes of cells with minor to major differences in antigen expression. These include expression of antigens representing multiple different cell lineages. Mesenchymal drift is the tendency of gliomas to progressively lose glial and gain mesenchymal features. Models of in vivo mesenchymal drift occur in glioma cell culture where mechanisms are more easily investigated than in situ. Neither exogenous protein absorption nor fibroblast overgrowth explain the phenomenon. Cells with the mesenchymal marker, fibronectin, overgrow GFAP-positive cells during explanation of gliomas. Many of these fibronectin-positive cells express cytologic and growth characteristics of neoplasia. The source of these cells is unknown. A leading candidate for the source of these neoplastic fibronectin-positive cells is the proliferation of vascular and mesenchymal cell elements of glioma tissue commonly called "endothelial proliferations". However, these elements in tissue do not display the same abnormalities of neoplasia as the fibronectin-positive cells in culture. Understanding this "tissue/explant paradox" may solve the conundrum of mesenchymal drift. In the absence of a counterpart in tissue of these neoplastic fibronectin-positive cells so abundant in glioma cell cultures, mechanisms of mesenchymal drift other than overgrowth of neoplastic mesenchyme must be considered. The occurrence of "dual cells" which express antigenic markers of entirely different cellular lineages suggests the possibility that neoplastic glia generate mesenchymal drift by altered gene expression. Various studies which suggest the capacity of cultured gliomas to alter phenotypic expression of their genes are critically examined and their relevance to mesenchymal drift discussed.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1979

The effects of various degrees of social pressure.

If the social pressure exerted against a minority is overwhelming (slavery, concentration camps) no cultural efforts of the slaves or prisoners can be expected. Absence of any pressure is not conducive to high achievements either. A moderate degree of social pressure especially when combined with a possibility of social acceptance will stimulate minority people to perform well and to try to achieve status and acceptance. The cultural climate in which persons belonging to the minority grew up often determines their choice of endeavor in which to prove themselves and to achieve. Arthur Toynbee's thesis of the importance of Challenge and Response for the evolution of civilisations and Hans Selye's concept of Stress in biology are related to the proposed hypothesis. The author shows the usefulness of his hypothesis on examples from the history of Blacks in America and of the Jews.

Acculturation↗