Operant discrimination of interoceptive urinary bladder stimulation in the monkey.
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Animals↗
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Results for “Extinction, Biological”
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Non-invasive in vivo infrared laser spectroscopy to analyse endogenous oxy-haemoglobin, deoxy-haemoglobin, and blood volume in the rat CNS.
Oxy-haemoglobin (HbO2) and deoxy-haemoglobin (Hb) are chromophores present in biological tissues. Near infrared spectroscopy (NIRS) is a non-invasive methodology based on the low extinction coefficient of tissue in the near infrared region. NIRS can be used to measure changes in the concentration of these chromophores, i.e., haemoglobin, in muscular tissue. In the present work, NIRS has been used for the non-invasive monitoring of HbO2, Hb, and blood volume (V: representing total haemoglobin, i.e., HbO2+Hb) in vivo in the whole rat brain. This has been performed by means of prototype instrumentation based on optic fibre probes placed in contact with the head of anaesthetised rats held in a stereotaxic frame. A preliminary test of the instrument has been performed on human muscle, i.e., lateral gastrocnemius, in order to evaluate the ability of the instrument to detect oxygenation changes. Afterwards, the effects of pharmacological treatments, such as systemic amphetamine and nicotine treatments on the CNS have been detected.
Amphetamine↗
Effects of training on neuronal activity and interactions in primary and higher visual cortices in the alert cat.
The effects of behavioral training on early visual representations have been elusive when assessed with firing rates. Learning-induced changes in performance, however, suggest that representations should encompass early cortical stages. Here, we address the question of whether training-induced effects are pertinent to neuronal activity outside the task proper, which is a requirement if subsequent perceptional processes should profit from training. To search for a neuronal signature of training effects beyond firing rates, we measured local field potentials, multiunit and isolated spike activity during passive viewing of previously learned stimulus response associations (S+ and S-) in areas 17/18 and 21a of two alert cats. Evoked potential responses as well as gamma oscillations even during the first 200 msec were found to be stronger for S+ in both areas. Most importantly, the later parts of the response (>200 msec) not only exhibit a highly significant difference in coherent gamma oscillations for S+ and S- both within and across areas, but are also characterized by a pronounced preference in firing rate for S+ in area 21a, whereas primary cortex shows a nonsignificant trend for weaker spike responses. From these results, we conclude that training-induced plasticity occurs in adult visual cortex for behaviorally relevant stimuli by changing primarily the temporal structure of neuronal activity at early stages of cortical processing, whereas later stages of cortical processing express the increased coherence of their input in elevated firing rates.
Action Potentials↗
Gross anatomy and ultrasonographic images of the reproductive system of the Sumatran rhinoceros (Dicerorhinus sumatrensis).
The Sumatran rhinoceros (Dicerorhinus sumatrensis) is the smallest of all the rhino species. It is one of the rarest mammals in the world and is in imminent danger of extinction. A study was carried out on seven wild-caught females, three wild-caught males and one captive born female Sumatran rhinoceros at the Sumatran Rhinoceros Breeding Centre in Sungai Dusun, Selangor, Malaysia, beginning 1990. As a result of the paucity of scientific information on the reproductive biology of the Sumatran rhinoceros, this study was conducted to obtain information, which could assist in the captive breeding of this endangered and near extinct species. The anatomy of the reproductive system was based on two post-mortem specimens and transrectal real-time ultrasonography in six adult females. Genitalia of the Sumatran rhinoceros were similar to those of other species of rhinoceroses. The cervix consisted of several folds, the uterus was bicornuate with a short body and prominent horns and the ovaries were completely covered by the fimbriated end of the fallopian tube. The internal genitalia could be imaged by ultrasonography. The testes were located within a pendulous scrotum. Two lateral projections were located at the base of the penis. A well-defined process glandis was present at the tip of the penis. The accessory sex glands and the testes could be imaged by ultrasonography.
Animals↗
A hypothesis: autonomic rhythms are reflected in growth lines of teeth in humans and extinct archosaurs.
A major determinant of tooth architecture is the arrangement of lines in dentin and in the enamel following the contour of the surface. Since the original description of these lines in the 19th century, they have been attributed to recurring events during tooth development. They have also attracted the attention of dental scientists and anthropologists; however, to date, studies of these structures have been largely theoretical and microscopic. We show here that the statistical properties of the spacing between the lines are similar in teeth from both ancient and modern humans and from extinct archosaurs, reptiles that lived tens or hundreds of millions of years ago-they also resemble heart rate variability of living humans. We propose that the deposition of these recurring structures is controlled by the autonomic nervous system. This control accounts for their regularity and recurrent nature and implies that the lines are an expression of a biologic rhythm which has been conserved throughout evolution. Details of the rhythms give clues to life styles in ancient civilizations and to the physiology of extinct archosaurs.
Animals↗
A molecular model for the evolution of endothermy in the theropod-bird lineage.
Ectothermy is a primitive state; therefore, a shared common ancestor of crocodiles, dinosaurs, and birds was at some point ectothermic. Birds, the extant descendants of the dinosaurs, are endothermic. Neither the metabolic transition within this lineage nor the place the dinosaurs held along the ectothermic-endothermic continuum is defined. This paper presents a conceptual model for the evolution of endothermy in the theropod-bird lineage. It is recognized that other animals (some fish, insects, etc.) are functionally endothermic. However, endothermy in other clades is beyond the scope of this paper, and we address the onset of endothermy in only the theropod/bird clade. The model begins with simple changes in a single gene of a common ancestor, and it includes a series of concomitant physiological and morphological changes, beginning perhaps as early as the first archosaurian common ancestor of dinosaurs and crocodiles. These changes continued to accumulate within the theropod-avian lineage, were maintained and refined through selective forces, and culminated in extant birds. Metabolic convergence or homoplasy is evident in the inherent differences between the endothermy of mammals and the endothermy of extant birds. The strength and usefulness of this model lie in the phylogenetic, genetic, evolutionary, and adaptive plausibility of each of the suggested developmental steps toward endothermy. The model, although conceptual in nature, relies on an extensive knowledge base developed by numerous workers in each of these areas. In addition, the model integrates known genetic, metabolic, and developmental aspects of extant taxa that phylogenetically bracket theropod dinosaurs for comparison with information derived from the fossil record of related extinct taxa.
Adaptation, Physiological↗
Coexistence of competing species by the oscillation of polymorphisms.
Scale-eating cichlids in Lake Tanganyika exhibit genetically determined lateral asymmetry, especially in their mouth-opening. Frequencies of the morphs oscillate due to strong frequency-dependent selection caused by the switching of prey's attention, and its delayed effect by their growth period. Two scale-eaters coexist in similar densities at south shore of the lake, with their morph frequencies oscillating in phase. We investigated the effect of the oscillation in morph frequencies to the coexistence of competing species. If the difference of two species' growth period is large, the oscillation facilitates the coexistence of the two species, while small difference of growth periods hinders their coexistence. In the latter case, the species with shorter growth period drives the other species to the extinction.
Animals↗
Some exact solutions of a generalized Fisher equation related to the problem of biological invasion.
The problem of biological invasion in a model single-species community is considered, the spatiotemporal dynamics of the system being described by a modified Fisher equation. For a special case, we obtain an exact solution describing self-similar growth of the initially inhabited domain. By comparison with numerical solutions, we show that this exact solution may be applicable to describe an early stage of a biological invasion preceding the propagation of the stationary travelling wave. Also, the exact solution is applied to the problem of critical aggregation to derive sufficient conditions of population extinction. Finally, we show that the solution we obtain is in agreement with some data from field observations.
Animals↗
[Anthropology of the father role].
The anthropological basic characteristics of the "father role" are presented by means of biological and early cultural aspects. The "father role" in its origin arose from mothercentered groups. For them only the "social fatherhood" was of any importance. The female primary groups accepted that man as being "the father" who could provide maximum protection for mother and children. It was not until the post ice-age extinction of many wild animals and the transition to owning of domestic animals--the capital of the shepherds--that patriarchy did develop. Now the "biological fatherhood" as a means of controlling female fertility changed to be the focal point within euroasian cultures.
Animals↗
Newly attained polyploidy and/or clonal reproduction in animals: the brink of extinction, or threshold to new frontiers?
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Agriculture↗
Extinction and exponential growth in random environments.
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Environment↗
The 'whole-animal approach' as a heuristic principle in neuroscience research.
Neuroscience embraces a heterogeneous group of disciplines. A conceptual framework that allows a better articulation of these different theoretical and experimental perspectives is needed. A 'whole-animal approach is proposed as a theoretical and hermeneutic tool. To illustrate the potential of this point of view, an overview of the research that has been performed in the extinction of fear-conditioned responses from Pavlov to the present is discussed. This is an example of how a whole-animal-based approach may help to organize and integrate basic and clinical neuroscience research. Our proposal is in agreement with recent statements calling for more integrative approaches in biological and neuropsychiatric research.
Animals↗
Two predators feeding on two prey species: a result on permanence.
For biological populations the precise asymptotic behavior of the corresponding dynamic system is probably less important than the question of extinction and survival of species. An ecological differential equation is called permanent if there exists some level k greater than 0 such that if the number xi(0) of species i at time 0 is positive for i = 1,2, ..., n then xi(t) greater than k for all sufficiently large times t Characterizations for permanence in a four-species prey-predator system modeled by the Lotka-Volterra equation are presented. The method used is based on a combination of two well-known approaches to dealing with permanence. An interesting feature is the occurrence of heteroclinic cycles.
Animals↗
Random amplified polymorphic DNA (RAPD) markers detect a single phenotype in lysimachia minoricensis J.J. Rodr. (Primulaceae), A wild extinct plant
Lysimachia minoricensis is a Mediterranean (Balearic Islands) endemic that is extinct in the wild but extant in botanical gardens. Previously, no variation at 22 isozyme loci was revealed in more than 150 analysed plants. Random amplified polymorphic DNA (RAPD) analysis was used to examine genetic variation among five individuals from each of eight botanical garden accessions (40 plants). No polymorphisms were detected at 201 amplified bands. This is the first report of RAPD monomorphism in a nonapomictic vascular plant. The lack of detectable genetic variation suggests that an extremely reduced gene pool was recovered in the field before its extinction. Although the screening of other genomic markers is feasible, it is suggested that the knowledge of biological and autoecological features should be prioritized before new re-introductions are attempted.
Journal Article↗
Complementary sex determination substantially increases extinction proneness of haplodiploid populations.
The role of genetic factors in extinction is firmly established for diploid organisms, but haplodiploids have been considered immune to genetic load impacts because deleterious alleles are readily purged in haploid males. However, we show that single-locus complementary sex determination ancestral to the haplodiploid Hymenoptera (ants, bees, and wasps) imposes a substantial genetic load through homozygosity at the sex locus that results in the production of inviable or sterile diploid males. Using stochastic modeling, we have discovered that diploid male production (DMP) can initiate a rapid and previously uncharacterized extinction vortex. The extinction rate in haplodiploid populations with DMP is an order of magnitude greater than in its absence under realistic but conservative demographic parameter values. Furthermore, DMP alone can elevate the base extinction risk in haplodiploids by over an order of magnitude higher than that caused by inbreeding depression in threatened diploids. Thus, contrary to previous expectations, haplodiploids are more, rather than less, prone to extinction for genetic reasons. Our findings necessitate a fundamental shift in approaches to the conservation and population biology of these ecologically and economically crucial insects.
Animals↗
Molecular characterization of a highly divergent HIV type 1 isolate obtained early in the AIDS epidemic from the Democratic Republic of Congo.
Numerous complete human immunodeficiency virus type 1 (HIV-1) genomes have been characterized for contemporary viruses, but few isolates obtained early in the HIV-1 epidemic have been studied. In this article, we describe the molecular characterization of an HIV-1 isolate (83CD003) that was obtained from an AIDS patient in Kinshasa, Democratic Republic of Congo (DRC) in 1983. The complete 83CD003 genome was sequenced in its entirety and found to encode uninterrupted open reading frames for all viral genes. Phylogenetic analysis revealed 83CD003 was a member of the major (M) group of HIV -1, but did not group with any of the known subtypes. Rather, it formed an independent lineage in all regions of its genome that was roughly equidistant from representatives of all other subtypes. Similarly, 83CD003 also did not cluster with any of several unclassified group M sequences that have been reported more recently to circulate in the DRC, suggesting that it may represent an early group M lineage thai is either rare or has gone extinct. The molecular clone of 83CD003 yielded an infectious virus after transfection into mammalian cells and its biological properties can be further studied.
Cell Line↗
Rat alpha 1-cysteine proteinase inhibitor. An acute phase reactant identical with alpha 1 acute phase globulin.
alpha 1-Cysteine proteinase inhibitor was isolated from normal and acute phase rat serum. The procedure, which includes successive fractionations on AcA 34, Cibacron blue Sepharose, DEAE-Sephacel, and hydroxyapatite, but avoids the use of an affinity chromatography step on a cysteine proteinase gel, led to the preparation of two electrophoretically distinct components. These resolved to a single band of apparent Mr = 68,000 when analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A slightly higher Mr was estimated from gel filtration studies, possibly related to the rather high carbohydrate content (15.25% of the dry weight). The purified protein exhibited strong inhibiting capacity towards papain with a Ki of 5 X 10(-11) M. As shown by immunochemical quantitation as well as functional activity, a 6-10-fold increase in the alpha 1-cysteine cysteine proteinase inhibitor content was recorded in inflammatory serum, thus demonstrating the protein to be a typical acute phase reactant. Its partial physicochemical characterization (Mr, isoelectric point, extinction coefficient, amino acid and carbohydrate compositions) shows large similarities with alpha 1 acute phase globulin whose biological function remains unknown, and which is present at the same concentration (about 0.5 g/liter) in normal serum. Identity between the two molecules has been further demonstrated by double immunodiffusion analysis since a continuous precipitating line was observed when purified alpha 1-cysteine proteinase inhibitor was reacted against anti-alpha 1 acute phase globulin and anti-alpha 1-cysteine cysteine proteinase inhibitor antibodies.
Amino Acids↗
Viruses as quasispecies: biological implications.
During viral infections, the complex and dynamic distributions of variants, termed viral quasispecies, play a key role in the adaptability of viruses to changing environments and the fate of the population as a whole. Mutant spectra are continuously and avoidably generated during RNA genome replication, and they are not just a by-product of error-prone replication, devoid of biological relevance. On the contrary, current evidence indicates that mutant spectra contribute to viral pathogenesis, can modulate the expression of phenotypic traits by subpopulations of viruses, can include memory genomes that reflect the past evolutionary history of the viral lineage, and, furthermore, can participate in viral extinction through lethal mutagenesis. Also, mutant spectra are the target on which selection and random drift act to shape the long-term evolution of viruses. The biological relevance of mutant spectra is the central topic of this chapter.
Evolution, Molecular↗