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PubMed1995

Plasmodium vinckei vinckei and P. yoelii nigeriensis: pattern of gametocyte production and development.

The morphological evolution and the periodicity of the gametocytes of two rodent malaria species were studied in the white mouse. Experiments with Plasmodium vinckei vinckei, a highly synchronous species, showed that the production of the sexual stages was periodic and was set by the specific rhythm of the asexual stages, i.e. the time of inoculation and the duration of the cycle in the blood. The duration of gametocytogenesis from merozoite to stage 0 was approximately 30 hours, and from stage 0 to stage III, 6 hours. Plasmodium yoelii nigeriensis which normally develops asynchronously in the blood was synchronized by a Percoll-glucose gradient fractionation. Although the duration of the asexual cycle was 18 hours, gametocytogenesis from merozoite to stage 0 lasted 24 hours and 12 hours from stage 0 to stage III. Some degree of sequestration was observed in the young gametocytes.

Animals↗
PubMed1995

[An electron microscopic study of the natural death of cyst cells in Sarcosporidia. II. Ultrastructural changes in the nuclei of cyst cells of Sarcocystis muris].

Nuclear changes in cyst cells, developing within 6 and 10 month old sarcocysts of Sarcocystis muris, were followed in terms of the programmed cell death phenomenon. This communication extends our previous studies in the cytoplasm of S. muris cyst cells (Radchenko et al., 1995) to include particular nuclear changes in different involve changes in nuclear configuration: the original spherical from is progressively substituted for irregular or lobulated shapes. This may suggest some corresponding changes in cytoskeleton, involved in formation and maintaining of some definite nuclear shape. In normal cyst cells, the nuclear chromatin appears as a filiform and reticulate structure with a few lumps made of granules and filaments. In the cyst stages subject to natural cell death, structural changes in nuclei involve disassembly of lumps into separate granules. Some spherical structures are seen outbudding from the nucleolus. These structures are presumably made of RNA-containing granules. The pattern of nucleolar segregation in S. muris cells resembles somewhat the changes in nucleoli reported for metazoan cells. However, the general picture of morphological evolution in the nuclei of S. muris cells, in the course of natural dying, differs from that in metazoan cell nuclei. No condensation of nuclear chromatin at the nuclear periphery, or blebbing of the nuclear and cytoplasmic membranes, so characteristic of the latter, was followed in the former. The peculiarities noticed in the sarcosporidia may reflect biological peculiarities of these specialized parasitic protozoa.

Animals↗
PubMed1995

[Plasmacytomas of the upper respiratory tract].

Nine cases of plasmocytoma of the upper airways in the current biopsy material are studied over a three-year period (1991-1993). Initially, all nine cases are clinically diagnosed as neoplasms: hemangiofibroma--one, chondrosarcoma--one, suspected carcinoma--five, and unspecified diagnosis--two. "Plasmocytoma" diagnosis is made on the ground of histological investigation of the material, supported histochemically and electron-microscopically. Some diagnostic problems (differential diagnosis inclusive) are discussed, as well as issues relating to the clinical and morphological evolution of the disease, and predilected gender and age groups.

Adult↗
PubMedDate not supplied

Failure of insulin-like growth factor 1 to improve radiocontrast nephropathy.

Exogenous insulin-like growth factor 1 (IGF-1) has been reported to improve experimental ischemic acute renal failure. We investigated a possible beneficial role of IGF-1 in a model of radiocontrast nephropathy induced by indomethacin, nitro-L-arginine ester and iothalamate. Multiple injections of recombinant human IGF-1 (or its vehicle) at 150 microg/100 g body weight/day were given for 24 h starting 1 h after radiocontrast, or initiated 1 day after the insults and continued for 48 h. IGF-1 prevented neither the fall in creatinine clearance nor medullary thick ascending limb necrosis observed at 24 h. Similarly IGF-1, given for 2 days after renal failure had been established, did not accelerate functional recovery at 72 h, did not ameliorate catabolism and did not alter the morphological evolution of intrarenal damage. In conclusion, IGF-1 had no beneficial effects in this model of radiocontrast nephropathy.

Acute Kidney Injury↗
PubMed1997

Vitamin A and apoptosis in colonic tumor cells.

The mechanism by which vitamin A prevents or delays chemical carcinogenesis remains unclear. In addition to these antimutagenic and antiproliferative activities, vitamin A seems able to induce programmed cell death. In this study, we assess the suggested role of vitamin A on the in vitro apoptosis induction in a rat colonic tumor cell line. Several concentrations of retinyl palmitate were added in the culture media. We observed cell proliferation by measuring the (3H)thymidine incorporation, cell differentiation by measuring the intestinal alkaline phosphatase expression, and apoptosis induction by DNA fragmentation and morphological evolution of adherent and floating cells. The results show that vitamin A decreases (3H)thymidine incorporation after 1 day of treatment, induces alkaline phosphatase expression, and increases the number of cells falling in apoptosis. This report confirms the role of vitamin A on the induction of cell differentiation, on the inhibition of cell proliferation and shows the vitamin A capacity to induce apoptosis. These results could be attractive to prevent development of colon cancer by vitamin A supplemented diets.

Adenocarcinoma↗
PubMedDate not supplied

[Dipetalonema lineage. New attempt at classification].

Through comparing the morphological evolution to the host range and the geographical distribution we can suggest Dipetalonema sensu-largo may be interpreted as a gondwanian lineage which may have evolved after the three main austral continents drifted apart. Therefore, we propose the following systematic splitting: --Sprattia n.gen., type species: S. venacavincola parasite of Australian Marsupials, which may be related to Litomosa; --Breinlia Yorke and Maplestone, 1926, and Breinlia (Johnstonema) (Yeh, 1957), parasite of Australian Marsupials; --Skrjabinofilaria (Travassos, 1925), parasite of American Marsupials; --Macdonaldius (Khanna, 1933), parasite of American Reptiles; --Dipetalonema (Orihelia) n.sub. gen., type species: D. (O.) anticlava, parasite of Dasypodidae; --Dipetalonema (Acanthocheilonema) (Cobbold, 1870), parasite of Insectivora, Carnivora, Pinnipedia, sometimes Rodents; --Dipetalonema (Molinema) (Freitas and Lent, 1939), parasite of Caviomorpha and Beavers; --Dipetalonema (Loxodontofilaria) (Berghe and Gillain, 1939), parasite of Ethiopian Ungulates; --Dipetalonema (Chenofilaria) (Kou, 1958), parasite of Asiatic Pholidota and Australian Marsupials; --Dipetalonema (Dipetalonema) (Diesing, 1861), parasite of American Primates; --Monanema Anteson, 1968, parasite of Rodents other than Cariomorpha; --Ackertia (Vaz, 1934), parasite of Caviomorpha; --Tetrapetalonema (Sandnema) n.sub.gen., type species: T. (S.) digitata, parasite of Asiatic Insectivora and Primates; --Tetrapetalonema (Tetrapetalonema) (Faust, 1935), parasite of Tupaidae, Platyrhinii, and, sometimes, American Rodents and Carnivora; --Tetrapetalonema (Esslingeria) n. sub.gen., type species: T. (E.) perstans, parasite of African African Anthropoidea and Humans; --Filarissima (Chabaud, 1974), parasite of Caviomorpha.

Animals↗
PubMed1991

A model for development and evolution of complex morphological structures.

How 'complex' or composite morphological structures like the mammalian craniomandibular region arise during development and how they are altered during evolution are two major unresolved questions in biology. Herein, we have described a model for the development and evolution of complex morphological structures. The model assumes that natural selection acts upon an array of phenotypes generated by variation in a variety of underlying genetic and epigenetic controlling factors. Selection refines the integration of the various morphogenetic components during ontogeny in order to produce a functioning structure and to adapt the organisms to differing patterns of environmental heterogeneity. The model was applied to the development and evolution of the mammalian mandible (which is used as a paradigm of complex morphological structures). The embryology of the mandible was examined in detail in order to identify the fundamental developmental units which are necessary to assemble the final morphological structure. The model is quite general since equivalent units exist for the development of many other biological structures. This model could be applied to many other developing morphological structures as well as other groups of organisms. For example, it can be applied to cell parameters during Drosophila development (Atchley, 1987). The model as discussed in this paper assumes that morphological changes in the mandible result from evolutionary changes in its underlying developmental units. The developmental units relate to characteristics of cellular condensations which are produced from the differentiation of embryonic neural crest cells. The developmental units include: the number of stem cells in preskeletal condensations (n), the time of initiation of condensation formation (t), the fraction of cells that is mitotically active within a condensation (f), the rate of division of these cells (r), and their rate of cell death (d). These units and their derivative structures are discussed in terms of types of tissue differentiation (chondrogenesis, osteogenesis, primary/secondary osteogenesis, intramembranous/endochondral ossification) and growth properties of major morphological regions of the mandible. Variation in these five units provides the developmental basis for ontogenetic and phylogenetic modification of mandibular morphology. We have discussed how these developmental units are influenced by (a) the cell lineage from which they arise, (b) epithelial-mesenchymal (inductive tissue) interactions, (c) regulation of cell differentiation, and (d) extrinsic factors such as muscles, teeth and hormones. Evidence was provided that variation in mandibular morphology is heritable, subject to modification by natural selection, and that divergence among different genetic stocks has apparently occurred through changes in these developmental units and their derivative structures.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1993

Effects of tamoxifen and CV 205502 on the morphology and the evolution of the noncancerous mouse mammary gland.

Tamoxifen (TAM, 0.01 mg/animal, three times a week) and the experimental prolactin-lowering CV 205502 (CV, 1 microgram/animal, daily) were administered prophylactically, alone or combined, to virgin C3H/Sy mice during the early period of promotion in this spontaneous mammary carcinogenesis system (end of 2nd-5th month of age), in order to study their influence on the morphology and evolution of the noncancerous mammary gland during therapy and after treatment cessation. During TAM administration the epithelial cells of the growing part of the gland exhibited myoepithelial- and, late in the treatment period, apoptotic-like features instead of the secretory ones expected, accompanied by intense basement membrane alterations, thickening of the surrounding connective tissue and arrested adipocyte maturation. These effects reversed progressively after drug withdrawal. The epithelial alterations were more intense and longer lasting in the TAM+CV-group, while growth arrest of the glands was observed in both groups parallel to the degree and the duration of these morphological changes. In these groups, tumor incidence was diminished, as expected, but the tumors that developed late after treatment cessation were of low histological differentiation. The above morphological observations show that TAM inhibits noncancerous mammary gland growth during the reproductive period by altering stromal and epithelial differentiation, effects that reverse progressively after treatment discontinuation and are potentiated by a prolactin-lowering agent in this animal study.

Adipocytes↗
PubMed2006

Elephant brain. Part I: gross morphology, functions, comparative anatomy, and evolution.

We report morphological data on brains of four African, Loxodonta africana, and three Asian elephants, Elephas maximus, and compare findings to literature. Brains exhibit a gyral pattern more complex and with more numerous gyri than in primates, humans included, and in carnivores, but less complex than in cetaceans. Cerebral frontal, parietal, temporal, limbic, and insular lobes are well developed, whereas the occipital lobe is relatively small. The insula is not as opercularized as in man. The temporal lobe is disproportionately large and expands laterally. Humans and elephants have three parallel temporal gyri: superior, middle, and inferior. Hippocampal sizes in elephants and humans are comparable, but proportionally smaller in elephant. A possible carotid rete was observed at the base of the brain. Brain size appears to be related to body size, ecology, sociality, and longevity. Elephant adult brain averages 4783 g, the largest among living and extinct terrestrial mammals; elephant neonate brain averages 50% of its adult brain weight (25% in humans). Cerebellar weight averages 18.6% of brain (1.8 times larger than in humans). During evolution, encephalization quotient has increased by 10-fold (0.2 for extinct Moeritherium, approximately 2.0 for extant elephants). We present 20 figures of the elephant brain, 16 of which contain new material. Similarities between human and elephant brains could be due to convergent evolution; both display mosaic characters and are highly derived mammals. Humans and elephants use and make tools and show a range of complex learning skills and behaviors. In elephants, the large amount of cerebral cortex, especially in the temporal lobe, and the well-developed olfactory system, structures associated with complex learning and behavioral functions in humans, may provide the substrate for such complex skills and behavior.

Animals↗
PubMed2004

Pleiotropic effects on mandibular morphology II: differential epistasis and genetic variation in morphological integration.

The evolution of morphological modularity through the sequestration of pleiotropy to sets of functionally and developmentally related traits requires genetic variation in the relationships between traits. Genetic variation in relationships between traits can result from differential epistasis, where epistatic relationships for pairs of loci are different for different traits. This study maps relationship quantitative trait loci (QTLs), specifically QTLs that affect the relationship between individual mandibular traits and mandible length, across the genome in an F2 intercross of the LG/J and SM/J inbred mouse strains (N = 1045). We discovered 23 relationship QTLs scattered throughout the genome. All mandibular traits were involved in one or more relationship QTL. When multiple traits were affected at a relationship QTL, the traits tended to come from a developmentally restricted region of the mandible, either the muscular processes or the alveolus. About one-third of the relationship QTLs correspond to previously located trait QTLs affecting the same traits. These results comprise examples of genetic variation necessary for an evolutionary response to selection on the range of pleiotropic effects.

Animals↗
PubMed2005

Molecular phylogeny, recent radiation and evolution of gross morphology of the rhubarb genus Rheum (Polygonaceae) inferred from chloroplast DNA trnL-F sequences.

BACKGROUND AND AIMS: Rheum, a highly diversified genus with about 60 species, is mainly confined to the mountainous and desert regions of the Qinghai-Tibetan plateau and adjacent areas. This genus represents a good example of the extensive diversification of the temperate genera in the Qinghai-Tibetan plateau, in which the forces to drive diversification remain unknown. To date, the infrageneric classification of Rheum has been mainly based on morphological characters. However, it may have been subject to convergent evolution under habitat pressure, and the systematic position of some sections are unclear, especially Sect. Globulosa, which has globular inflorescences, and Sect. Nobilia, which has semi-translucent bracts. Recent palynological research has found substantial contradictions between exine patterns and the current classification of Rheum. Two specific objectives of this research were (1) to evaluate possible relationships of some ambiguous sections with a unique morphology, and (2) to examine possible occurrence of the radiative speciation with low genetic divergence across the total genus and the correlation between the extensive diversification time of Rheum and past geographical events, especially the recent large-scale uplifts of the Qinghai-Tibetan Plateau. METHODS: The chloroplast DNA trnL-F region of 29 individuals representing 26 species of Rheum, belonging to seven out of eight sections, was sequenced and compared. The phylogenetic relationships were further constructed based on the sequences obtained. KEY RESULTS: Despite the highly diversified morphology, the genetic variation in this DNA fragment is relatively low. The molecular phylogeny is highly inconsistent with gross morphology, pollen exine patterns and traditional classifications, except for identifying all samples of Sect. Palmata, three species of Sect. Spiciformia and a few species of Sect. Rheum as corresponding monophyletic groups. The monotypic Sect. Globulosa showed a tentative position within the clade comprising five species of Sect. Rheum. All of the analyses revealed the paraphyly of R. nobile and R. alexandrae, the only two species of Sect. Nobilia circumscribed by the possession of large bracts. The crude calibration of lineages based on trnL-F sequence differentiation implied an extensive diversification of Rheum within approx. 7 million years. CONCLUSIONS: Based on these results, it is suggested that the rich geological and ecological diversity caused by the recent large-scale uplifts of the Qinghai-Tibetan Plateau since the late Tertiary, coupled with the oscillating climate of the Quaternary stage, might have promoted rapid speciation in small and isolated populations, as well as allowing the fixation of unique or rare morphological characters in Rheum. Such a rapid radiation, combined with introgressive hybridization and reticulate evolution, may have caused the transfer of cpDNA haplotypes between morphologically dissimilar species, and might account for the inconsistency between morphological classification and molecular phylogeny reported here.

Biological Evolution↗
PubMed1976

[New data on non-parallel evolution of karyotype and morphology in Phyllotinae (Rodents, Cricetidae)].

The non-concordance of the morphological and chromosomal evolution in the Phyllotinae is discussed in the light of the latest karyological data concerning the genus Zygodontomys: individual specimens of this genus from French Guiana present a new chromosomal formula with a high number 2 N; their karyotypical and morphological peculiarities are sufficient to warrant creating a new species Z. reigi. The great variability of the karyotypes appearing in this genus permits one to think that the various groups could represent successive aspects of the same chromosomal evolution, an increase of the number 2 N preceding an eventual decrease.

Animals↗
PubMed1988

A detailed morphological evaluation of the evolution of the haemostatic plug in normal, factor VII and factor VIII deficient dogs.

A standardized injury of the nail cuticle of normal, factor VII and factor VIII deficient dogs was used to study the evolution of the morphological changes occurring within the forming and formed haemostatic plug at the site of vascular injury. The morphological changes occurring were documented by light and transmission electron microscopy (TEM). Randomized measurements were made of the distances between adjacent platelets as a function of platelet interdigitation or compaction and the degree of dilatation of the open canalicular system (OCS) was used as an indicator of the degree of platelet activation. Fibrin deposition was noted both in terms of its location and the point in time at which it first appeared. TEM demonstrated major differences between the factor VIII deficient and the normal and factor VII deficient groups. In the normal animals the intermembrane distance showed noticeable changes with the platelets becoming tightly interdigitated at the time bleeding stopped. During the same period the OCS became dilated. These changes, which were not seen in the factor VIII deficient animals, continued until many platelets lost their intracellular content and became balloon cells or ghosts and fibrinous transformation became prominent. Although those events did occur in the factor VII deficient state, each was delayed and resulted in significant differences between the factor VII and normal animals suggesting that the extrinsic pathway may play an important role in initiating the changes noted. The results suggested that the generation of thrombin and/or factor Xa is essential to promote the initial stabilization of the platelet plug as well as initiating its subsequent consolidation by fibrinous transformation.

Animals↗
PubMed2005

Evolution of male morphology in the ant genus Cardiocondyla.

The ant genus Cardiocondyla is characterized by a striking male polymorphism, with wingless, local fighter males (ergatoid males) with life-long spermatogenesis, and winged, peaceful disperser males with limited sperm supply. We examined the evolution of male morphology by reconstructing the phylogeny of Cardiocondyla from sequences of the mitochondrial COI/COII and 16S RNA genes from 13 of the 15 species, of which males are known. Data suggest that male polymorphism is ancestral and that winged males were lost convergently in several taxa, such as C. elegans, C. batesii, and C. mauritanica. Saber-shaped mandibles and lethal fighting among adult ergatoid males might probably have been the original condition, from which strong, shear-shaped mandibles and attacks directed predominantly against freshly eclosed, not yet sclerotized males might have evolved once. The evolution of queen number from ancestral polygyny to derived monogyny appears to be associated with a switch in the behavior of ergatoid males from fighting to mutual tolerance.

Animals↗
PubMed2004

The spermatozoon of Eurasian murine rodents: Its morphological diversity and evolution.

The murine rodents are the most speciose subfamily of mammals. Here the morphology of the spermatozoon, as determined by scanning and transmission electron microscopy of representative species from four Eurasian clades, is described. Much interspecific variability in all components of the spermatozoon was found to occur, although most species have a bilaterally flattened sperm head with a single apical hook of variable length and orientation. Ultrastructural observations indicate that this apical hook invariably contains a nuclear projection as well as a large extension of the subacrosomal cytoskeleton, as a perforatorium rostrally, and a complex asymmetrical acrosomal extension. These spermatozoa also have relatively long tails that are attached to the lower concave surface of the sperm head. Uniquely, in species in the Apodemus clade, the apical hook is orientated caudally. In a few species a highly derived sperm head morphotype that does not contain an apical hook is present. These sperm heads vary in morphology from being globular in two species of Bandicota, to bilaterally flattened and paddle-shaped in Tokudaia and Micromys. In spermatozoa of the latter two genera the subacrosomal cytoskeleton, which is less extensive than in species with a hooked sperm head, forms an apical extension, but that is not the case in Bandicota. In all species where the sperm head lacks an apical hook the acrosome is more symmetrical. The sperm tail is much shorter in these species, with attachment to the head occurring on the ventral surface in Tokudaia and basal in Micromys and the two species of Bandicota. As the sperm head morphotype with a complex apical hook is present in all the major clades of murine rodents, it is likely to be a plesiomorphic character within each of these clades, with the nonhooked sperm heads, which vary greatly in structure between species of the different lineages, probably being independently derived. The ultrastructural organization of the sperm head of Bandicota, but not those of Micromys or Tokudaia, suggest divergence in some of the morphological events associated with sperm-egg interaction at the time of fertilization.

Animals↗
PubMed2006

Major clades of parmelioid lichens (Parmeliaceae, Ascomycota) and the evolution of their morphological and chemical diversity.

Parmelioid lichens comprise about 1500 species and have a worldwide distribution. Numerous species are widely distributed and well known, including important bioindicators for atmospheric pollution. The phylogeny and classification of parmelioid lichens has been a matter of debate for several decades. Previous studies using molecular data have helped to establish hypotheses of the phylogeny of certain clades within this group. In this study, we infer the phylogeny of major clades of parmelioid lichens using DNA sequence data from two nuclear loci and one mitochondrial locus from 145 specimens (117 species) that represent the morphological and chemical diversity in these taxa. Parmelioid lichens are not monophyletic; however, a core group is strongly supported as monophyletic, excluding Arctoparmelia and Melanelia s. str., and including Parmeliopsis and Parmelaria. Within this group, seven well-supported clades are found, but the relationships among them remain unresolved. Stochastic mapping on a MC/MCMC tree sampling was employed to infer the evolution of two morphological and two chemical traits believed to be important for the evolutionary success of these lichens, and have also been used as major characters for classification. The results suggest that these characters have been gained and lost multiple times during the diversification of parmelioid lichens.

Ascomycota↗
PubMed2004

The evolution of larval morphology and swimming performance in ascidians.

The complexity of organismal function challenges our ability to understand the evolution of animal locomotion. To meet this challenge, we used a combination of biomechanics, phylogenetic comparative analyses, and theoretical morphology to examine evolutionary changes in body shape and how those changes affected swimming performance in ascidian larvae. Results of phylogenetic comparative analyses suggest that coloniality evolved at least three times among ascidians and that colonial species have a convergent larval morphology characterized by a large trunk volume and shorter tail length in proportion to the trunk. To explore the functional significance of this evolutionary change, we first verified the accuracy of a mathematical model of swimming biomechanics in a solitary (C. intestinalis) and a colonial (D. occidentalis) species and then ran numerous simulations of the model that varied in tail length and trunk volume. The results of these simulations were used to construct landscapes of speed and cost of transport predictions within a trunk volume/tail length morphospace. Our results suggest that the reduction of proportionate tail length in colonial species resulted in improved energetic economy of swimming. The increase in the size of larvae with the origin of coloniality facilitated faster swimming with negligible energetic cost, but may have required a reduction in adult fecundity. Therefore, the evolution of ascidians appears to be influenced by a trade-off between the fecundity of the adult stage and the swimming performance of larvae.

Animals↗