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1.
A reconstruction of the adaptive pattern of the Miocene hominoid "Ramapithecus," supported by comparative data and morphological comparisons, is presented. It is based upon the completely known dentition, inferior portion of the face, and on the paleoecology and geographic distribution of "Ramapithecus" bearing deposits. The known adaptive and morphological patterns of the "Ramapithecus" species are almost indistinguishable from those of the contemporary species of Sivapithecus, which has taxonomic priority. The "Ramapithecus" species are therefore referred to Sivapithecus, a dryopithecine genus which apparently radiated throughout Eurasia and Africa during the Middle Miocene.  相似文献   

2.
A polyphasic PCR-DGGE approach was used to describe the microbial population occurring in natural whey cultures (NWCs) for water-buffalo Mozzarella cheese production. Total microbial community was assessed without cultivation by analyzing DNA directly extracted from the original samples of NWC. In addition, DNA extracted from bulks of cells formed by harvesting colonies from the serial dilution agar plates of a variety of culture media was used to profile the "cultivable" community. The 16S rDNA V3 region was amplified using DNA from NWC as well as DNA from bulks as templates and the amplicons were separated by DGGE. The microbial entities occurring in NWCs were identified by partial 16S rDNA sequencing of DGGE bands: four lactic acid bacteria (LAB) closest relative of Streptococcus thermophilus, Lactococcus lactis, Lactobacillus delbrueckii and Lactobacillus crispatus were revealed by the analysis of DNA directly extracted from NWC while two other LAB, Lactobacillus fermentum and Enterococcus faecalis, were identified by analyzing DNA from the cultivable community. The developed PCR-DGGE analysis of the "cultivable" community showed good potential in evaluating microbial diversity of a dairy environment: it usefully highlighted the bias introduced by selective amplification when compared to the analysis of the total community from NWC and allowed suitability of media and growth conditions to be evaluated. Moreover, it could be used to complete the culture independent study of microbial diversity to give information on concentration ratios among species occurring in a particular environment and can be proposed for rapid identification of dominant microorganisms in alternative to traditional tools.  相似文献   

3.
Data from 24 craniofacial dimensions were compiled for samples representing all the human populations of the world. These were converted into C scores and used to construct Euclidean Distance dendrograms. The populations of the world are best depicted as 8 major regional clusters representing: Africa, Amerind, Asia-Mainland, Australo-Melanesia, Eskimo-Siberia, Europe, India, and Jomon-Pacific. The mainland Asian cluster divided into northern and southern components. The Neolithic in both areas is less clearly associated with the northern or southern components and may represent the form of their undifferentiated precursors. This needs to be tested by the addition of further specimens and an adequate sample from South China. Mongols are peripheral members of the Asia-Mainland cluster and should not be thought of as typifying the region as a whole. The use of the term "Mongoloid" is inappropriate in both theory and practice.  相似文献   

4.
    
The \"thrifty genotype hypothesis\" has become firmly entrenched as one of the orienting concepts in biomedical anthropology, since first being proposed by Neel (1962 Am. J. Hum. Genet. 14:353-362) over 40 years ago. Its influence on inquiries into the evolutionary origins of diabetes, lactose tolerance, and other metabolic disorders can hardly be underestimated, as evidenced by its continued citation in many top scientific and medical journals. However, its fundamental assumption, that foragers are more likely to experience regular and severe food shortages than sedentary agriculturalists, remains largely untested. The present report tests this assumption by making a cross-cultural statistical comparison of the quantity of available food and the frequency and extent of food shortages among 94 foraging and agricultural societies as reported in the ethnographic record. Our results indicate that there is no statistical difference (P < 0.05) in the quantity of available food, or the frequency or extent of food shortages in these reports between preindustrial foragers, recent foragers, and agriculturalists. The findings presented here add to a growing literature that calls into question assumptions about forager food insecurity and nutritional status in general, and ultimately, the very foundation of the thrifty genotype hypothesis: the presumed food shortages that selected for a \"thrifty\" metabolism in past foraging populations.  相似文献   

5.
Idealistic morphology as perhaps the most important historical manifestation of typology is very suitable for a historical analysis of Ernst Mayr's “Essentialism Story”, which postulates an antagonism between “typological thinking” and “population thinking”. We show that German-language idealistic-morphological theories consisted of two clearly distinguishable parts. The cornerstone of these theories was the concept of the type as an abstract pattern representing a certain class of phenomena and embodying the norm of this class. The primary objective of pure typology was to create a non-phylogenetic classification system for living organisms based on structurally explicable characters. Thus, typology, as a non-phylogenetic foundation of idealistic morphology, was conceptually neutral with respect to hypotheses of evolutionary mechanisms. Typology was often accompanied by concepts such as Lamarckism, orthogenesis, creationism, essentialism, etc. These peripheral (with respect to pure typology) concepts were autonomous constructions and did not represent a direct logical consequence of typology. In our view “population thinking”, as part of the Darwinian theory of evolutionary mechanism, could not be directly opposed to “typological thinking”. Rather, it was peripheral concepts such as essentialism or creationism that led to conflicts between the Modern Synthesis and idealistic morphology.  相似文献   

6.
The precursors of the amino acid yeast pool are intermediates of either the glycolytic or the tricarboxilic acid pathway (TCA). Accordingly, the influence of the metabolism (fermentative or respiratory) on the internal amino acid pool of the yeast Saccharmyces cerevisiae was established by measuring the intracellular amino acid concentration of the "grande" strain IF1256 and its "petite" mutant either in steady-state or when shifting from fermentative to respiratory conditions. Under steady-state conditions, when the cells only respire, there is a decrease in nearly all the amino acids whose precursors are intermediates of the glycolytic pathway. When the metabolism is exclusively fermentative, the opposite change takes place. This effect is not observed in those amino acids whose precursors come from the TCA cycle. However, in continuous culture and at dilution rates lower than 0.06 h(-1), there is an enormous increase in the concentration of all the amino acids in both strains, whatever their precursor, whereas, in batch cultures, both strains undergo variations in the concentration of most amino acids, when entering stationary growth phase. Results therefore indicate that, the fact that the cells ferment or respire effectively affect their amino acid pool according to their precursors coming from the glycolytic or the TCA pathway, but other parameters, such as growth rate or exponential versus stationary phase, have a much stronger effect on yeast amino acid concentration.  相似文献   

7.
Pseudomonas tolaasii, causing brown blotch disease on cultivated mushrooms, and yielding a white line precipitate towards P. “reactans”, has been shown to induce lysis of erythrocytes. Some Finnish strains isolated from diseased mushroom fruit bodies, although harboring the typical features of P. tolaasii, proved to be distinct, and have been allocated to a nov. sp. P. costantinii. We examined in these study whether all brown blotch causing agents were hemolytic. The induction of erythrocytes lysis seemed to be a rather common feature of mushroom associated-pseudomonads, especially for strains involved in the production of a white-line-in agar.  相似文献   

8.
  总被引:8,自引:0,他引:8  
In a membrane bioreactor (MBR), fast growth of anammox bacteria was achieved with a sludge residence time (SRT) of 12 days. This relatively short SRT resulted in a--for anammox bacteria--unprecedented purity of the enrichment of 97.6%. The absence of a selective pressure for settling, and dedicated cultivation conditions led to growth in suspension as free cells and the complete absence of flocs or granules. Fast growth, low levels of calcium and magnesium, and possibly the presence of yeast extract and a low shear stress are critical for the obtainment of a completely suspended culture consisting of free anammox cells. During cultivation, a population shift was observed from Candidatus \"Brocadia\" to Candidatus \"Kuenenia stuttgartiensis.\" It is hypothesized that the reason for this shift is the higher affinity for nitrite of \"Kuenenia.\" The production of anammox bacteria in suspension with high purity and productivity makes the MBR a promising tool for the cultivation and study of anammox bacteria.  相似文献   

9.
Relationships between lengths of long bones in early medieval Alamanns and in recent white Americans do not differ significantly. Lacking evidence of any differences between the contribution of trunk length to stature in the two samples, formulas for estimating stature based on relationships of bone lengths to stature in an American sample thus appear applicable to the Alamannic material.  相似文献   

10.
  总被引:1,自引:0,他引:1  
Mixed cultures submitted to acetate \"feast\" and \"famine\" cycles are able to store intracellularly high quantities of polyhydroxybutyrate (PHB). It was demonstrated in a previous study that the intracellular PHB content can be increased up to 78.5% (g HB/gVSS) of cell dry weight in a sequencing batch reactor (SBR) with optimised operating conditions. The specific PHB formation rate was also shown to be higher for mixed cultures than for pure cultures. Such high intracellular PHB contents and specific productivity open new perspectives for the industrial production of polyhydroxyalkanoates (PHA) using mixed cultures instead of pure cultures. The main goal in this work was to develop a mathematical model of mixed cultures envisaging the optimisation of PHB production. A relatively simple two-compartments cell model was developed based on experimental observations and other models proposed in the literature. A convenient experimental planing allowed to identify the kinetic parameters and yield coefficients. Experiments were performed with and without ammonia limitation enabling the analysis of PHB formation independently of the cell growth process. The experimental true yields partially confirm the theoretical values proposed in the literature. The final model exhibited high accuracy in describing the process state of most experiments performed, thus opening good perspectives for future model-based optimisation studies.  相似文献   

11.
    
The aim of the present study was to investigate possible neurophysiological effects of intermittent 15 sec on/off cycle, 60 Hz, 10 μT magnetic field exposure on patients with perceived “electromagnetic hypersensitivity” (EHS), and control subjects during rest and performance of a mental arithmetic task. Twenty participants (15 female, 5 male, 31–60 years old, mean 45.8 ± 0.7 years) were invited from the group of EHS patients. Twenty volunteers (15 female, 5 male, 31–59 years old, mean 45.0 ± 0.7 years?) served as a control group. The test protocol consisted of a set of examinations: EEG, visual evoked potentials, electrodermal activity, ECG, and blood pressure. The total duration of the test was 40 min, divided into two 10 min rest periods and two 10 min periods of mathematical performance. Magnetic field and sham exposures were presented randomly during these periods, resulting in four different conditions: Field‐Rest, Sham‐Rest, Field‐Math, and Sham‐Math. The data showed significant main effects of the Group factor (EHS vs. control subjects) on heart rate (F1,80 = 20.6; P < 0.01), heart rate spectrum ratio (F1,80 = 9.5; P = 0.02), and electrodermal activity (F1,76 = 4.2; P = 0.04), whereas EEG characteristics did not differ between groups. The Condition factor (mathematical task vs. relaxed) showed main effects for heart rate (F1,80 = 14.8; P < 0.01), heart rate spectrum ratio (F1,80 = 7.8; P = 0.06), electrodermal activity (F1,76 = 56.8; P < 0.01), and alpha and theta spectral bands of EEG. Magnetic field exposure did not affect autonomous system or electroencephalographic variables of either group. These data do not indicate that EHS patients or control are affected by low‐level 60 Hz magnetic field exposure. However, persons reporting EHS differed from the control subjects in baseline values of investigated physiological characteristics. Perhaps EHS patients have a rather distinctive physiological predisposition to sensitivity to physical and psychosocial environmental stressors. Bioelectromagnetics 22:457–462, 2001. © 2001 Wiley‐Liss, Inc.  相似文献   

12.
    
Leprosy was a well-recognized and dreaded disease in medieval Europe (5th-15th century AD). It is reported to have reached Germany with the Roman invasion. A much larger fraction than previously assumed appears to have been affected by leprosy in the medieval period. This article estimates the frequency (i.e., the prevalence at death) of leprosy among adult people buried in the Lauchheim early medieval cemetery. Seven different dichotomous osteological lesions indicative of leprosy are analyzed, and it is possible to score at least one of these conditions on 110 adult skeletons (aged 15 or more). The scores were transformed to a statistic--lambda (lambda)--indicating the likelihood that the person to whom the skeleton belonged suffered from leprosy. The analyses indicate that 16% (95% confidence interval: 9-23%) of adult people in Lauchheim died with osteological signs of leprosy. Leprosy was significantly more prevalent among men than women. The lambda statistic indicates that people who died with signs of leprosy did not differ in the distribution of age at death from those who did not have such signs. Some of the leprosy-related lesions had a statistically significant nonrandom dispersal on the cemetery; but there is no clear pattern to this and the significant results could be easily attributed to a type-1 error in the statistical analysis.  相似文献   

13.
14.
  总被引:1,自引:0,他引:1  
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15.
We screened samples from high temperature biotopes for 16S rRNA genes of the novel archaeal phylum "Nanoarchaeota". Positive PCR amplifications were obtained from Yellowstone National Park, Uzon Caldera, and an abyssal vent system. These sequences form a cluster with the sequence of "Nanoarchaeum equitans", indicating a wide distribution of this phylum.  相似文献   

16.
ABSTRACT. Feeding behaviour of fifth instar tobacco hornworm caterpillars, Manduca sexta (Johansen) (Lepidoptera; Sphingidae), eating tobacco or artificial diet, is quantitatively described. The insects grow at the same rate on both foods. There is no daily rhythm of feeding behaviour. For most insects, feeding on either food occurs in bouts with the lengths of interfeed gaps and of feeding bouts appearing to be distributed randomly. However, in many insects there is a strong correlation between the length of a feeding period and that of the preceding non-feeding period.
The proportion of time spent feeding on tobacco is much greater than on artificial diet. On tobacco, feeding periods are separated by shorter interfeed gaps than on the artificial diet, while the rate of bout initiation is similar on either food.
On both tobacco and artificial diet, the proportion of time spent feeding increases as the fifth stadium proceeds. This is due to both longer feeding bouts and shorter gaps. The rate of food acquisition within bouts does not change during the stadium.  相似文献   

17.
  总被引:1,自引:0,他引:1  
One-cell hamster embryos placed in culture have always shown a complete block to development at the two-cell stage. In a preliminary study using a chemically defined culture medium containing 20 amino acids (HECM-1), many one-cell embryos were able to escape the \"two-cell block\" and develop to the four-cell stage. Use of a simpler formulation containing only the amino acids hypotaurine and glutamine revealed marked inhibitory and stimulatory effects of adding the other amino acids. In the first experiment, 19 amino acids were separately examined for effects on one-cell embryo development. Six amino acids (phenylalanine, valine, isoleucine, tyrosine, tryptophan, and arginine) inhibited embryo development (reduced mean cell number; MCN), and three others (glycine, cystine, and lysine) stimulated development (increased MCN), compared with basic medium containing only glutamine and hypotaurine (low control). When the responses with the six inhibitory amino acids were totalled, only 3 of 185 (2%) one-cell embryos reached the six-or seven-cell stage compared to a total of 15 of 76 (20%) embryos that developed to these stages using the three stimulatory amino acids. When tested together in a second experiment, the six inhibitory amino acids significantly reduced the MCN, from 4.28 +/- 0.44 (low control) to 3.71 +/- 0.55. In this group, 17 of 117 (15%) of one-cell embryos reached more than four-cell and only 4 of 117 (3%) reached six- or 7-cell stages, compared with 39 of 117 (33%) and 12 of 117 (10%), respectively, for the basal medium group.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

18.
Body shape differences between two benthophagous, sympatric cichlid species, Ctenopharynx pictus and Otopharynx sp. “heterodon nankhumba” were examined for 14 morphometric characters using measurements obtained from 11 morphological landmarks and additional 6 characters from the head region using principal component and regression analyses. The two species, though not closely related, superficially resemble each other and, being benthic feeders, directly compete for food resources unless morphological differences lead to trophic specialization. Hence, the present study explores the presence of such morphological variations. Principal component analysis (PCA), revealed that only four characters loaded highly on PC II and, therefore, account for most of the variations in the external morphology between the two species. C. pictus has longer lower jaws reflecting longer gape, and a shorter abdominal cavity than O. sp. “heterodon nakhumba”. The regression analyses showed significant differences in the allometric coefficients of the lower jaw and abdominal cavity, which might have contributed to differences in overall shape detected between the two species. The difference in gape size between the two species may be related to different feeding habits employed by each species, and such specializations are suggested to reduce interspecific competition for food resources. We suggest that the ensuing ecological separation promotes sympatry of these two species.  相似文献   

19.
Data from the article by Brodsky et al. (2000) have been examined in order to confirm that the fluctuations they report are not random but have a rhythmic basis, thereby verifying their conclusions regarding the existence of periodicity in protein synthesis. Reasons are outlined why oscillations should be expected in all cellular biochemical studies. Associated practical problems are briefly discussed together with comments on the validity and value of less rigorous methods of analysis. The subject of aliasing is raised as justification for doubting the validity of much published data, especially where periodicity has not been suspected. The existence of oscillations indicates the need for a thorough re-evaluation of our understanding of cell biochemistry.  相似文献   

20.
    
While dominance relationships have been widely studied in chimpanzees, in bonobos, dominance style and linearity of hierarchy are still under debate. In fact, some authors stated that bonobo hierarchy is nonlinear/ill-defined, while others claimed that it is fairly linear. In this paper, we test the hypothesis that a shift in group composition determines changes in linearity of hierarchy. To test this hypothesis, we collected data on one of the largest captive groups in the world, in the Apenheul Primate Park (The Netherlands). We investigated the linearity of the hierarchy in two different periods, with a shifting group composition. We used the corrected Landau's index and David's scores to estimate which animals were most dominant. The major overall result of our study is that hierarchy is fairly nonlinear in this group: during the first study period (eight adults), the hierarchy was nonlinear, whereas during the second one (six adults), it failed to reach statistical linearity. We argue that the reduction of the number of adults is the principal factor affecting linearity. We also found that dominance interactions were evenly distributed across sex classes in both study periods. Furthermore, no correlation was observed between age/body weight and rank. As for the overall dominance relationship between males and females, our results suggest that there is no exclusive female dominance in the Apenheul group. The dominance style of bonobos may be loose and differentially expressed in diverse groups or in the same group, along with shifting conditions.  相似文献   

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