Basidiospore Wall Ultrastructure of the False-Truffle Hydnangium and Its Phylogenetic Significance

Mycologia ◽  
1993 ◽  
Vol 85 (6) ◽  
pp. 890 ◽  
Author(s):  
Gregory M. Mueller ◽  
Angelica von Hofsten ◽  
Anette Axen ◽  
Betty A. Strack
Keyword(s):  
Phylogenetic Significance ◽  
Wall Ultrastructure ◽  
False Truffle

Basidiospore Wall Ultrastructure of the False-Truffle Hydnangium and Its Phylogenetic Significance

Mycologia ◽  
1993 ◽  
Vol 85 (6) ◽  
pp. 890-893
Author(s):  
Gregory M. Mueller ◽  
Angelica Von Hofsten ◽  
Anette Axén ◽  
Betty A. Strack
Keyword(s):  
Phylogenetic Significance ◽  
Wall Ultrastructure ◽  
False Truffle

Cell Wall Ultrastructure in Three Strains of a Cariogenic Streptococcus

1971 ◽  
Vol 29 ◽  
pp. 338-339
Author(s):  
M. J. Kramer ◽  
Alan L. Coykendall
Keyword(s):  
Cell Wall ◽  
Dental Caries ◽  
Streptococcus Mutans ◽  
Microscopic Study ◽  
Electron Microscopic Study ◽  
Genetic Heterogeneity ◽  
Morphological Characteristics ◽  
Electron Microscopic ◽  
Dna Reassociation ◽  
Wall Ultrastructure

During the almost 50 years since Streptococcus mutans was first suggested as a factor in the etiology of dental caries, a multitude of studies have confirmed the cariogenic potential of this organism. Streptococci have been isolated from human and animal caries on numerous occasions and, with few exceptions, they are not typable by the Lancefield technique but are relatively homogeneous in their biochemical reactions. An analysis of the guanine-cytosine (G-C) composition of the DNA from strains K-1-R, NCTC 10449, and FA-1 by one of us (ALC) revealed significant differences and DNA-DNA reassociation experiments indicated that genetic heterogeneity existed among the three strains. The present electron microscopic study had as its objective the elucidation of any distinguishing morphological characteristics which might further characterize the respective strains.

Hominin transition to Upper Pliocene

2017 ◽  
Author(s):  
Francisco J. Ayala ◽  
Camilo J. Cela-Conde
Keyword(s):  
Brain Development ◽  
Late Pleistocene ◽  
Technological Progress ◽  
Homo Sapiens ◽  
Middle Pleistocene ◽  
Evolutionary Significance ◽  
Australopithecus Afarensis ◽  
Phylogenetic Significance ◽  
Homo Neanderthalensis ◽  
Surprising Discovery

This chapter analyzes the transition of the hominins from the Middle Pleistocene to the Late Pleistocene. Two alternative models are explored, the “Multiregional Hypothesis” (MH) and the “Replacement Hypothesis,” and how each model evaluates the existing relationships between the taxa Homo neanderthalensis and Homo sapiens. Next is the investigation of the transitional (or “archaic,” if this grade is taken into account) exemplars found in Europe, Africa, and Asia and their evolutionary significance. In particular, the comparison between H. erectus and H. sapiens in China and Java is investigated, as the main foundation of the MH. The chapter ends with the surprising discovery of Homo floresiensis and its description and interpretations concerning its taxonomic and phylogenetic significance. The correlation between brain development and technological progress is at odds with the attribution of perforators, microblades, and fishing hooks to a hominin with a small cranial volume, similar to that of Australopithecus afarensis.

scholarly journals A novel primary bile acid in the Shoebill stork and herons and its phylogenetic significance

2002 ◽  
Vol 43 (5) ◽  
pp. 685-690 ◽  
Author(s):  
L.R. Hagey ◽  
C.D. Schteingart ◽  
H-T. Ton-Nu ◽  
A.F. Hofmann
Keyword(s):  
Bile Acid ◽  
Phylogenetic Significance ◽  
Primary Bile Acid

Adaptive function and phylogenetic significance of novel skeletal features of a new Devonian microconchid tubeworm (Tentaculita) from Wyoming, USA

2021 ◽  
pp. 1-15
Author(s):  
Michał Zatoń ◽  
Mingxi Hu ◽  
Mercedes di Pasquo ◽  
Paul M. Myrow
Keyword(s):  
Middle Devonian ◽  
New Genus ◽  
Adaptive Strategy ◽  
Phylogenetic Significance ◽  
New Genus And Species ◽  
Adaptive Function ◽  
Faunal Assemblage ◽  
Early Devonian ◽  
Narrow Channels ◽  
Algal Thalli

Abstract A new genus and species of microconchid tubeworm, Aculeiconchus sandbergi n. gen. n. sp., is described from the Givetian (Devonian) Maywood Formation of Cottonwood Canyon, Wyoming, USA. It possesses unique hollow spines of various lengths on the tube underside, a position previously undocumented for these fossils. Like some cyclostome bryozoans possessing basal tubular extensions, the basal spines of Aculeiconchus n. gen. were presumably also used for fixation to flexible substrata, e.g., algal thalli, which is a previously undocumented adaptive strategy in microconchids. Together with other skeletal features, such basal spines could suggest that ‘lophophorate’ microconchids, unlike the other tentaculitoids, might be phylogenetically not as distant from bryozoans as previously thought. The Maywood Formation, which contains a few-millimeters thick, monospecific shell accumulation of the microconchids described herein, records deposition in an estuarine brackish setting within narrow channels that were cut into underlying strata. The microconchids were opportunistic taxa that repeatedly colonized these salinity-stressed estuarine channels, leading to a series of adaptive innovations, including colonization of plant stems during the Early Devonian (Beartooth Butte Formation) and possibly flexible, soft-algal substrata during the Middle Devonian (Maywood Formation, this study). Tectonic quiescence during the Early and Middle Devonian indicates that erosion and subsequent deposition of the Maywood and the underlying Beartooth Butte Formation channels were responses to major eustatic events. Over a span of nearly 30 Myr, channels were cut successively during lowstand conditions and a distinctive faunal assemblage with microconchids tracked marine transgressions into the channels. UUID: http://zoobank.org/394c8b32-d5e7-411e-8e56-6fb9f55bbb8a

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