Origin of euconodont elements

Primitive euconodont elements from the Upper Cambrian of Sweden are investigated histologically and compared with co-occurring elements of paraconodonts. The proposed close relationship between the two groups is confirmed. Typical euconodont and paraconodont elements are bridged by intermediate forms. The ontogenetic development of the early euconodont elements shows striking similarities to the evolutionary development from paraconodonts to euconodonts, suggesting that evolution generally followed a peramorphic pattern (“recapitulation”). The conodont crown originated through extension of the growth lamellae around the whole element, accompanied by stronger mineralization. The first denticulation in Proconodontus arose when a jagged posterior edge in juvenile specimens was enhanced by the subsequent deposition of growth lamellae, a process comparable to the regeneration of broken tips. The most primitive euconodont elements probably erupted from the epithelium earlier in ontogeny than in more advanced forms. After the appearance of the phosphatic crown, conodont elements underwent a very rapid morphological differentiation. Cordylodus may have arisen from Proconodontus serratus.

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The Morphogenetic Influence of Innervation on the Ontogenetic Development of Muscle-spindles

Development ◽

10.1242/dev.5.3.283 ◽

1957 ◽

Vol 5 (3) ◽

pp. 283-292

Author(s):

J. Zelená

Keyword(s):

Skeletal Muscle ◽

Early Stage ◽

Experimental Studies ◽

Morphological Differentiation ◽

Muscle Spindles ◽

Limb Bud ◽

Ontogenetic Development ◽

Muscular Tissue ◽

Neurula Stage

The influence of innervation on the differentiation of peripheral structures during ontogenesis has been studied mainly in skeletal muscle. It has been shown in a number of experimental studies on amphibians that the morphological differentiation of the whole extremity as well as its muscular tissue takes place normally after removal of the medullary plate at the gastrula or neurula stage, although the limb developing without innervation is smaller and its musculature is atrophic (Harrison, 1903, 1904; Hooker, 1911; Hamburger, 1928). In the chick transplantation of the limb-bud into the coelom cavity or on to the chorioallantois leads in the first phase to muscular differentiation despite the fact that the limb is not innervated (Hunt, 1932; Hamburger & Waugh, 1940; Eastlick, 1943; Eastlick & Wortham, 1947). Degeneration and sarcolysis follow the initial differentiation at a very early stage.

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Molecular and Phylogenetic Analysis of Pyridoxal Phosphate- Dependent Acyltransferase of Exiguobacterium acetylicum

Zeitschrift für Naturforschung C ◽

10.1515/znc-2009-11-1222 ◽

2009 ◽

Vol 64 (11-12) ◽

pp. 891-898 ◽

Cited By ~ 1

Author(s):

Narayanan Rajendran ◽

Colby Smith ◽

Williard Mazhawidza

Keyword(s):

Amino Acid ◽

Pyridoxal Phosphate ◽

Extreme Environments ◽

Pcr Amplification ◽

Evolutionary Development ◽

Sequencing Analysis ◽

Amino Acid Residues ◽

Exiguobacterium Acetylicum ◽

Close Relationship ◽

Relationship Of

The pyridoxal-5’-phosphate (PLP)-dependent family of enzymes is a very diverse group of proteins that metabolize small molecules like amino acids and sugars, and synthesize cofactors for other metabolic pathways through transamination, decarboxylation, racemization, and substitution reactions. In this study we employed degenerated primer-based PCR amplification, using genomic DNA isolated from the soil bacterium Exiguobacterium acetylicum strain SN as template. We revealed the presence of a PLP-dependent family of enzymes, such as PLP-dependent acyltransferase, and similarity to 8-amino-7-oxononoate synthase. Sequencing analysis and multiple alignment of the thymidine-adenine-cloned PCR amplicon revealed PLP-dependent family enzymes with specific confering codes and consensus amino acid residues specific to this group of functional proteins. Amino acid residues common to the majority of PLP-dependent enzymes were also revealed by the Lasergene MegAlign software. A phylogenetic tree was constructed. Its analysis revealed a close relationship of E. acetylicum to other bacteria isolated from extreme environments suggesting similarities in anabolic adaptability and evolutionary development.

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Juniperus excelsa s. str. in crimea – differentiation and history inferred from genetic and morphological markers

Folia Forestalia Polonica ◽

10.2478/ffp-2021-0028 ◽

2021 ◽

Vol 63 (4) ◽

pp. 276-288

Author(s):

Małgorzata Mazur ◽

Katarzyna A. Jadwiszczak ◽

Agnieszka Bona ◽

Yuliya Krasylenko ◽

Oleg Kukushkin ◽

...

Keyword(s):

Phylogenetic Analyses ◽

Haplotype Diversity ◽

Geographic Location ◽

Morphological Differentiation ◽

Species Range ◽

Internal Transcribed Spacer Region ◽

Crimean Peninsula ◽

Molecular Features ◽

Juniperus Excelsa ◽

Close Relationship

Abstract Juniperus excelsa s. str. (Greek juniper) in Crimea is a relic species on the limits of its range, and represents the Mediterranean flora in the Sub-Mediterranean part of the peninsula. Its origin and history in this area remains unresolved. We aimed to analyze phylogeny and potential demographic expansion of the juniper in the Crimea as well as to study its morphological differentiation. We analyzed plant material from 59 trees inhabiting eight populations. Genetic variation assessments were based on the four non-coding chloroplast DNA (cpDNA) fragments and the nuclear internal transcribed spacer region ITS1-5,8S-ITS2 (ITS). To examine the morphological differentiation, eight measured/counted traits of cones, seeds, and shoots were chosen and eight ratios were calculated. Morphological parameters were compared using ANOVA, Student’s t test, discrimination analysis and Kruskal-Wallis and U Mann-Whitney tests. Two cpDNA fragments were polymorphic and, in total, 10 cpDNA haplotypes were found. Haplotype diversity (Hd) ranged from 0.0 to 0.9. Based on both cpDNA and ITS sequences variation, phylogenetic analyses revealed a close relationship of the Crimean junipers to the individuals from other parts of the species range. In general, our molecular results confirmed the low level of genetic differentiation of J. excelsa individuals inhabiting different parts of the species range, likely resulting from a common ancestry. Only slight morphological differences were found between populations with different geographic location or habitat. The analyzes showed the distinctness of the populations from the southern part of the coast. Some unique morphological and molecular features of southern coastal populations imply that they are remnants of Late Pleistocene abundant forests. We suggest that the recent fragmentation of the Juniperus populations in the Crimean Peninsula could have arisen during the Atlantic period of the Holocene.

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Ontogeny and ventral median suture of the ptychaspidid trilobiteAsioptychaspis subglobosa(Sun, 1924) from the Furongian (Upper Cambrian) Hwajeol Formation, Korea

Journal of Paleontology ◽

10.1666/09-101r.1 ◽

2010 ◽

Vol 84 (2) ◽

pp. 309-320 ◽

Cited By ~ 12

Author(s):

Tae-Yoon Park ◽

Duck K. Choi

Keyword(s):

Early Phase ◽

Evolutionary History ◽

Sister Group ◽

Ontogenetic Development ◽

Alternative Mode ◽

Upper Cambrian ◽

Ontogenetic Study ◽

History Of ◽

Later Phase

The order Asaphida has been characterized by the possession of a globular protaspis and a ventral median suture. the superfamily Dikelocephaloidea was included in the Asaphida, although there has been no reliable ontogenetic information for this superfamily, and thus whether dikelocephaloids had a protaspis of globular shape has remained unclear. the ontogenetic study of the dikelocephaloid trilobite,Asioptychaspis subglobosa,from Korea reveals that the protaspis ofA. subglobosais not of globular morphology but of general benthic adult-like morphology, heralding that the Dikelocephaloidea may not be closely related to other trilobite groups within the Order Asaphida. This protaspid morphology is clearly distinguished from the highly globular protaspis of the Remopleuridioidea, which has been considered the sister group to the Dikelocephaloidea. in addition, the ontogenetic development of the free cheeks shows thatA. subglobosapossessed anteriorly yoked free cheeks during the early phase of development but formed a ventral median suture by splitting the yoked cheeks in the later phase of ontogeny. This contrasts with the previously suggested mode of ventral median suture formation of the Order Asaphida. This alternative mode of ventral median suture formation ofA. subglobosa,along with non-asaphoid protaspid morphology, warrants removal of the Dikelocephaloidea from the current Order Asaphida. This study further demonstrates that the ventral median suture did not evolve only once in the evolutionary history of trilobites. With the addition of the mode here documented forAsioptychaspis,the ventral median suture is now known to have developed independently and in a different fashion at least three times in the history of Cambrian trilobites.

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Minding the Close Relationship

10.1017/cbo9780511527845 ◽

1999 ◽

Cited By ~ 11

Author(s):

John H. Harvey ◽

Julia Omarzu

Keyword(s):

Close Relationship

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The Solution Strategy as an Indicator of the Developmental Stage of Preschool Children’s Mental-Rotation Ability

Journal of Individual Differences ◽

10.1027/1614-0001/a000017 ◽

2010 ◽

Vol 31 (2) ◽

pp. 95-100 ◽

Cited By ~ 21

Author(s):

Claudia Quaiser-Pohl ◽

Anna M. Rohe ◽

Tobias Amberger

Keyword(s):

Preschool Children ◽

Mental Rotation ◽

Latent Class ◽

Preschool Age ◽

Stage Model ◽

Solution Strategy ◽

Thinking Aloud ◽

Transition Analysis ◽

Solution Strategies ◽

Close Relationship

The solution strategies of preschool children solving mental-rotation tasks were analyzed in two studies. In the first study n = 111 preschool children had to demonstrate their solution strategy in the Picture Rotation Test (PRT) items by thinking aloud; seven different strategies were identified. In the second study these strategies were confirmed by latent class analysis (LCA) with the PRT data of n = 565 preschool children. In addition, a close relationship was found between the solution strategy and children’s age. Results point to a stage model for the development of mental-rotation ability as measured by the PRT, going from inappropriate strategies like guessing or comparing details, to semiappropriate approaches like choosing the stimulus with the smallest angle discrepancy, to a holistic or analytic strategy. A latent transition analysis (LTA) revealed that the ability to mentally rotate objects can be influenced by training in the preschool age.

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Speeded Paper-Pencil Sustained Attention and Mental Speed Tests

Journal of Individual Differences ◽

10.1027/1614-0001.29.4.205 ◽

2008 ◽

Vol 29 (4) ◽

pp. 205-216 ◽

Cited By ~ 9

Author(s):

Stefan Krumm ◽

Lothar Schmidt-Atzert ◽

Kurt Michalczyk ◽

Vanessa Danthiir

Keyword(s):

Sustained Attention ◽

Time Pressure ◽

Factor Model ◽

Higher Order ◽

Future Research ◽

Perceptual Speed ◽

Speed Factor ◽

Close Relationship ◽

Task Processing ◽

Order Factor

Mental speed (MS) and sustained attention (SA) are theoretically distinct constructs. However, tests of MS are very similar to SA tests that use time pressure as an impeding condition. The performance in such tasks largely relies on the participants’ speed of task processing (i.e., how quickly and correctly one can perform the simple cognitive tasks). The present study examined whether SA and MS are empirically the same or different constructs. To this end, 24 paper-pencil and computerized tests were administered to 199 students. SA turned out to be highly related to MS task classes: substitution and perceptual speed. Furthermore, SA showed a very close relationship with the paper-pencil MS factor. The correlation between SA and computerized speed was considerably lower but still high. In a higher-order general speed factor model, SA had the highest loading on the higher-order factor; the higher-order factor explained 88% of SA variance. It is argued that SA (as operationalized with tests using time pressure as an impeding condition) and MS cannot be differentiated, at the level of broad constructs. Implications for neuropsychological assessment and future research are discussed.

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