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13 recordsLinked to original sources
PubMed2025

Rapid Radiations Outweigh Reticulations During the Evolution of a 750-Million-Year-Old Lineage of Cyanobacteria.

Species are a fundamental unit of biodiversity. Yet, the existence of clear species boundaries among bacteria has long been a subject of debate. Here, we studied species boundaries in the context of the phylogenetic history of Nostoc, a widespread genus of photoautotrophic and nitrogen-fixing cyanobacteria that includes many lineages that form symbiotic associations with plants (e.g. cycads and bryophytes) and fungi (e.g. cyanolichens). We found that the evolution of Nostoc was characterized by eight rapid radiations, many of which were associated with major events in the evolution of plants. In addition, incomplete lineage sorting associated with these rapid radiations outweighed reticulations during Nostoc evolution. We then show that the pattern of diversification of Nostoc shapes the distribution of average nucleotide identities (ANIs) into a complex mosaic, wherein some closely related clades are clearly isolated from each other by gaps in genomic similarity, while others form a continuum where genomic species boundaries are expected. Nevertheless, recently diverged Nostoc lineages often form cohesive clades that are maintained by within-clade gene flow. Boundaries to homologous recombination between these cohesive clades persist even when the potential for gene flow is high, i.e. when closely related clades of Nostoc co-occur or are locally found in symbiotic associations with the same lichen-forming fungal species. Our results demonstrate that rapid radiations are major contributors to the complex speciation history of Nostoc. This underscores the need to consider evolutionary information beyond thresholds of genomic similarity to delimit biologically meaningful units of biodiversity for bacteria.

Phylogeny↗
PubMed1979

Phylogeny and the herniated disc.

Using a phylogenic classification of the spine, one can identify precisely the numerical location of any vertebra or disc, including vertebrae with junctional anomalies at transitional zones. Such precision permitted comparisons of myelographic reports of sites of disc disease with the actual levels of extradural deformities and of charted levels of disc operations with the actual levels of disc curettements. Among 100 patients there were 33 with phylogenic or junctional departures from the human mode. Among these 33 there was a combined total of 18 identification errors, and there were four entries at incorrect levels. Preoperative landmarking would appear to be obligatory.

Adult↗
PubMed1979

The spectrum of Ebstein's anomaly of the tricuspid valve.

The structure of the tricuspid valve in 14 cases of Ebstein's malformation is described and compared with that in the normal heart. The anomalous hearts showed a spectrum of malformation, varying from minimal displacement of the adjacent parts of the septal and inferior leaflets of the tricuspid valve to presence of an imperforate membrane or muscle shelf between the inlet and trabecular zones of the right ventricle. In "typical" Ebstein's anomaly the anterosuperior leaflet was abnormally attached so as to partially obstruct the route from right atrium to distal right ventricle, the communication between these chambers being between the abnormally attached leaflet and its malformed neighbors. In two hearts, a muscular shelf produced stenosis between inlet and trabecular portions, but a competent valve was produced at this site, the atrialized part of the right ventricle being of normal thickness. The significance of these findings is considered with regard to possible methods of repair. Description of the anomaly is facilitated by considering the right ventricle as possessing inlet, trabecular, and outlet portions. The essence of the anomaly is displacement of the tricuspid orifice to the junction of the inlet and trabecular ventricular zones.

Ebstein Anomaly↗
PubMed1978

Ventral porencephaly: a cerebral defect associated with multiple congenital anomalies.

An infant with multiple congenital anomalies was found at autopsy to have a porencencephalic defect on the ventral surface of the left frontal lobe. The intracranial defect was seen in association with an anomalous configuration of the circle of Willis. The zone of tissue destruction corresponded to the vascular territory of the anterior choroidal and lenticulo-striate branches of the proximal middle cerebral arteries, which were absent on the left. The developmental anomaly of the circle of Willis may have predisposed to tissue destruction by compromising cerebral perfusion at midgestation, a stage of rapid brain growth.

Abnormalities, Multiple↗
PubMed1977

[The follow-up of high risk pregnancies with the determination of estriol 16-glucuronid excretion. Second: Excretion in preeclampsia, post maturity, intrauterine growth retardation, diabetes, Rh incompatability and intrauterine fetal deaths (author's transl)].

The estriol 16-glucuronid excretion was determined in 186 urine samples in cases with preeclampsia, post maturity, pregnancies past the expected date of confinement, intra-uterine fetal deaths, congenital anomalies, Rhesus incompatability and diabetes mellitus. In groups with mild dystrophy, severe dystrophy, and intra-uterine fetal death, three zones of estriol 16-glucuronid excretion were determined. Zone 1 is suggestive of a possible fetal impairment. Zone 2 shows a high probability of fetal impairment and Zone 3 was considered as lethal zone suggestive of imminent intra-uterine fetal death. The degree of rhesus incompatability, disease of the fetus or of diabetogenic fetopathy was not recognizable by the estriol 16-glucuronid excretion.

Abnormalities, Multiple↗
PubMed1978

[X-ray anatomic features of the skeleton in the 47, XYY syndrome].

The data are represented on the examination of 11 men with 47, XYY karyotype, roengenography of some parts of their skeletals including. The result are compared with the data on investigation of 430 human males chosen from a population. This anomaly in the karyotype stipulates, in the skeletal formation, a tendency to high stature, a certain flattening in the head of the radiocarpal articulation, the kneepan and the distal contour of the femoral bone. Nearly in a half of all observations valgus deviation of the ulnar articulation was somewhat increased, in 3 cases--inhibition of some synostoses in the growth zones of the extremities was noted. A supposition is made that in males the insidence of cleft in sesamoid bones in the lower extremities is increased in the presence of the extra Y-chromosome.

Adult↗
PubMed1978

[Familial manifestation of a circumscribed cutaneous aplasia of the vertex associated, in one case, with cardiac malformation (author's transl)].

The authors described a one-month-old baby girl showing a zone of cutaneous aplasia of the vertex; she presented, in addition, an extensive interventricular communication. A family study enabled them to ascertain that her three-year-old brother had a scarred alopecial area starting at the bregmatic region and continuing backwards along the median line; the six-year-old sister also had a scar on the vertex. Neither parent had any anomaly of the scalp. It would appear that circumscribed cutaneous aplasias generally result from a localised developmental defect, the exact mechanism of which remains unexplained. Circumscribed cutaneous aplasia which is sporadic and isolated in the majority of cases of trisomy 13) can, however, be transmitted as a mendelian trait, usually dominant. In the family under study, the absence of any lesion in the parents and the very small distance separating the two communes from which they originated rather favour a recessive autosomal mode of heredity.

Female↗
PubMed1979

Evidence for the occurrence of early modifications in the 'glia limitans' layer of the neocortex of the reeler mutant mouse.

A comparative EM study of the marginal zone of the neocortex in E15 foetuses of normal and 'reeler' mice was carried out. In the mutant a direct contact between 'proneurons' and the superficial basal lamina bordering the 'glia limitans' layer was observed. Since this phenomenon occurs with a much higher frequency in the mutant than in the normal animal, it is thought to be important in the genesis of the 'reeler' anomaly. In the discussion, different hypotheses concerning the possible nature, mechanism and importance of the interaction described are suggested.

Animals↗
PubMed2026

ARX mutation-associated interneuron defects provide insights into mechanisms underlying developmental epilepsies.

Cortical interneuron (cIN) dysfunction is associated with various neurodevelopmental and neurological disorders, including developmental epilepsies, autism spectrum disorders and intellectual disabilities. Mutations in ARX (aristaless-related homeobox) are linked to these conditions, with or without accompanying structural brain anomalies. We previously demonstrated that the loss of Arx in the mouse ganglionic eminence, the birthplace of cINs, is associated with seizures, whereas its loss in cortical excitatory neuron progenitor cells results in structural anomalies but no seizures. To elucidate the pathophysiological role of ARX in cINs and its relationship to seizure phenotype, Arx conditional mutant mouse lines were investigated using Gad2- and Nkx2.1-Cre drivers to target distinct populations in the cIN lineage. Our data demonstrate that ARX abrogation results in defects in cIN density and distribution, as well as perinatal lethality. In these mice, we observed defects in cell cycle exit, a biased loss of the marginal zone migration stream of cINs, shifts in cell fate from caudal ganglionic eminence to medial ganglionic eminence identity, and a reduced number of parvalbumin⁺ and somatostatin⁺ cINs, with parvalbumin⁺ cINs being more severely affected. Single-cell RNA sequencing combined with chromatin immunoprecipitation and sequencing revealed that ARX regulates key processes involved in cell cycle progression, cIN subtype differentiation and cIN migration. Investigation of one downregulated target gene, Lmo1, uncovered a potential mechanism by which ARX regulates the number and distribution of cINs in the cortex. Cortical slice cultures demonstrate that LMO1 inhibits cIN migration by repressing Cxcr4 expression, which encodes a key receptor involved in cortical guidance. These data indicate that ARX positively regulates cIN migration by derepressing LMO1's repressive role. Consistent with our mouse model, we observed a significant loss of parvalbumin+ and somatostatin+ cINs in the brain of a patient carrying a pathogenic variant of ARX, who was diagnosed with developmental epileptic encephalopathy. Together, our data provide novel insights into how ARX and its target genes regulate cIN development and migration and into the pathogenic mechanisms underlying a spectrum of neurodevelopmental disorders linked to loss of ARX.

Animals↗
PubMed1977

[Transformation of the temporomandibular joint in the treatment of sagittal bite anomalies].

The results from distocclusion and mesiocclusion treatments were radiologically evaluated in 89 patients. In two experiments, mesiocclusion and distocclusion were produced in monkeys by means of cemented inclined planes. The transformations thus achieved were evaluated by radiography, histology and craniometry. The treatment of distocclusion results in an increase in size of the mandible, of the angle of the mandible, and of the lower third of the face. The head of the condyle erects itself. Reactive tissue changes (activation of the osteoblasts and osteoclasts, accelerated ossification of the cartilage) were seen in the dorsal part of the head of the condyle. Thus, the theory of Breitner is not confirmed. There were no resorption phenomena at the articular eminence and in the anterior part of the head of the condyle, and no so-called pressure and traction zones.

Animals↗
PubMed1977

[Neuropsychologic characteristics of children with retarded mental development].

The neuropsychological study of 50 children with the diagnosis of mental retardation permitted to devide them into 2 groups according to the character and severity of disturbances. In the first group disturbances of some cortical functions are of a dynamical character, in the second group there is a stable insufficiency. The prevalence of the defect is different: in the first group phenomena of a dysfunction are observed in the zone of verbal tasks and in the second--in the verbal and nonverbal areas. The consideration of these results from the point of view of the conjugate brain activity allows one to state in the first group a dysfunction of the left (speech) hemisphere along with the normal development of the right hemisphere. In the second group there is a dysfunction of both hemispheres which points to a more expressed severity of disturbances. A special neuropsychological study of the functions of the frontal lobes protecting the highest forms of behaviour regulation demonstrates their different insufficiency in children with mental retardation. The first group shows impulsiveness and instability of an arbitrary control, the second group--enertness, perseveration in programming movements and actions. However, the anomaly of mental development in the second group of children may be related to mental retardation, since the marked defects are compensated by the possibility of holding intentions and capability of purposeful activity.

Child↗
PubMed1979

Comparison of visual function studies in two cases of senile macular degeneration.

In this paper two relatively early cases of senile macular degeneration are compared by making use of a number of tests of visual function, some relatively new, coupled with observation of the fundus and analysis by fluorescein angiography. The functional tests include visual acuity, the sustainedlike and transientlike functions which are believed to test inner retinal receptive field properties and to have origin in the inner and outer plexiform layers, the Stiles-Crawford function which reflects the directional sensitivity and orientation of photoreceptors, and increment threshold curves. In one case there was evidence of inner retinal involvement at the time the tests were conducted, but, because the Stiles-Crawford function remained essentially normal, it is assumed that the receptors were not disturbed relative to their orientation. In this case (as in many others), the zone or area exhibiting functional change does not necessarily match the area exhibiting anatomical change as observed by examination of the fundus, fundus photography, and fluorescein angiography. In the second patient there is evidence of both anomalous inner retinal function and disturbance in receptor alignment. The later suggests disorientation of the receptor bed. These findings correlated with the fundus observation and fluorescein angiographic evidence of a leak, resulting in the presence of serous fluid beneath the neurosensory retina. With resolution of this fluid there was a return of the functional tests toward normal. At this time, it is not possible to determine whether, in two cases, the functional changes are proceeding on a parallel course, but are at different stages, or whether they are the expression of somewhat different anomalies.

Aged↗
PubMed1977

[Ultrastructural characteristics of human spermatozoa with elongated head (author's transl)].

In most spermatozoa with elongated head persists an abundant complex membranous system between the post-acromial zone and the post-nuclear region. This system has a periodical structure, the apparently spherical unit of which is 120 A in diameter; it develops between the two sheaths of the nuclear envelope and seems to be continuous with the innermost one. This system can be seen in spermatids during normal spermiogenesis and in most cases it seems to be eliminated either with cytoplasmic droplet or by swelling into the nucleus. Now, a comparable but permanent structure is located all around the head of the normal spermatozoon at the height of the posterior part of the post-acrosomial sheath. This latter system is organized under plasma membrane and only visible on the ultrathin sections made with an appropriate incidence. For some authors it might contribute to maintain the integrity of the head and that of the neck of the spermatozoon and so it might be comparable to a system of septal desmosomes. For other authors periodic structures might favour adherence and fusion of spermatozoon with ovocyte during fertilisation. The particular membranous system that we describe persists often in the spermatozoon with elongated head, by its exuberance it can trouble or delay the fusion of the two gametes at the moment of fertilisation, which might explain the sterility of men bearing this anomaly.

Acrosome↗