scholarly journals Evolutionary Trends in the Ventral Nerve Cord of the Stingless Bees ( Meliponini)

2017 ◽  
Vol 9 (1) ◽  
pp. 117-129
Author(s):  
Alvaro Wille
Keyword(s):  
Nerve Cord ◽  
Abdominal Segment ◽  
Stingless Bees ◽  
Ventral Nerve Cord ◽  
Evolutionary Trends ◽  
The Third ◽  
Starting Point ◽  
Primitive Forms ◽  
Trigona Fulviventris ◽  
Generalized Type

There are, in relation to the number of ganglia, three main types of ven­tral nerve cords in the adult stingless bees: 1) Those which have two ganglia in the thorax and five in the abdomen, 2) those which have two ganglia in the thorax and four in the abdomen, and 3) those which have three ganglia in the thorax and four in the abdomen. Intermediate types between those listed exist.The most generalized ventral nerve card was found in the workers of Trigona fulviventris, where each ganglion lies only one segment ahead from its respective segment (Fig. 1, A). When this generalized type of nerve cord is taken as a starting point, there are two major recognizable evolutionary trends almong the stingless bees (Fig. 1). One trend is toward the fusion of ganglion 7 with the preceding abdominal ganglion. This occurs independently in the several subgenera of Trigona, with a series of intermediate steps (Fig. 3, A to H). Among some of the species of Melipona there is also a tendency of fusion of ganglion 7 with ganglion 6 (Fig. 4, A to D ) but none of the species of Mélipona dissected was found with those ganglia completely fused.The second trend noted is toward cephalization of the nerve cord ( Fig. 2). This occurs only in Melipona. Here the abdominal ganglia migrate from two to four segments ahead from their respective segments. As a result, gan­glion 3, which in primitive forms was located in the second abdominal segment (first metasomal segment), has moved well inside the thorax. The presence of ganglion 3 in the thorax is characteristic of all the species of Melipona. The highest type of cephalization is found only in a few species, such as MeliPona flavipennis in which ganglia 4 and 5 have moved into the second abdominal segment, and ganglia 6 and 7 into the third. Therefore, in this type, the card extends in the abdomen only as far as the third abdominal segment (second metasomal segment, Fig. 2, E ) . There are, of course, intermediate types.

Extracellular filaments in the perineurium of the florida lobster, Panulirus argus

1987 ◽  
Vol 45 ◽  
pp. 784-785
Author(s):  
Roy J. Baerwald ◽  
Lura C. Williamson
Keyword(s):  
Blood Brain Barrier ◽  
Glial Cells ◽  
Tannic Acid ◽  
Nerve Cord ◽  
Ventral Nerve Cord ◽  
Florida Keys ◽  
Panulirus Argus ◽  
Brain Barrier ◽  
Cacodylate Buffer ◽  
Nerve Cords

In arthropods the perineurium surrounds the neuropile, consists of modified glial cells, and is the morphological basis for the blood-brain barrier. The perineurium is surrounded by an acellular neural lamella, sometimes containing scattered collagen-like fibrils. This perineurial-neural lamellar complex is thought to occur ubiquitously throughout the arthropods. This report describes a SEM and TEM study of the sheath surrounding the ventral nerve cord of Panulirus argus.Juvenile P. argus were collected from the Florida Keys and maintained in marine aquaria. Nerve cords were fixed for TEM in Karnovsky's fixative and saturated tannic acid in 0.1 M Na-cacodylate buffer, pH = 7.4; post-fixed in 1.0% OsO4 in the same buffer; dehydrated through a graded series of ethanols; embedded in Epon-Araldite; and examined in a Philips 200 TEM. Nerve cords were fixed for SEM in a similar manner except that tannic acid was not used.

Teologiczne znaczenie osoby i natury w świetle chrystologii Soboru Chalcedońskiego

2018 ◽  
Vol 31 (4) ◽  
pp. 146-165
Author(s):  
Giacomo Calore
Keyword(s):  
The Third ◽  
Starting Point

Council of Chalcedon is an actual closing point for Christology and a starting point for anthropology. Behind the teachings of the Council of Chalcedon,together with later clarifications added by the Second and the Third Councils of Constantinople, there were centuries of dispute between the School of Alexandria and the School of Antioch about the person and natures of Christ (4th/5th – 7th centuries). Therefore the light shed on the man by patristic Christology concerns understanding of his being a person and his nature. The analysis of the Council’s teachings of faith shows that these two concepts belong to two different areas which means that every man, following the man Jesus, is a person whose dignity is on a different level than his natural features (mind, will, consciousness, etc.) – in other words, it originates from transcendence. Simultaneously, person is a relational reality because it puts a man in a relation with God in which the nature can be improved, the nature whose essence – since it was adopted by Logos – is to be capax Dei, or ability to grow in following Christ.

Law and Economics

2020 ◽  
pp. 84-102
Author(s):  
Daniel B. Kelly
Keyword(s):  
Economic Analysis ◽  
First Generation ◽  
Law And Economics ◽  
Private Law ◽  
Foreseeable Future ◽  
Business Associations ◽  
The Third ◽  
Starting Point ◽  
The Law ◽  
The Impact

This chapter analyzes how law and economics influences private law and how (new) private law is influencing law and economics. It focuses on three generation or “waves” within law and economics and how they approach private law. In the first generation, many scholars took the law as a starting point and attempted to use economic insights to explain, justify, or reform legal doctrines, institutions, and structures. In the second generation, the “law” at times became secondary, with more focus on theory and less focus on doctrines, institutions, and structures. But this generation also relied increasingly on empirical analysis. In the third generation, which includes scholars in the New Private Law (NPL), there has been a resurgence of interest in the law and legal institutions. To be sure, NPL scholars analyze the law using various approaches, with some more and some less predisposed to economic analysis. However, economic analysis will continue to be a major force on private law, including the New Private Law, for the foreseeable future. The chapter considers three foundational private law areas: property, contracts, and torts. For each area, it discusses the major ideas that economic analysis has contributed to private law, and surveys contributions of the NPL. The chapter also looks at the impact of law and economics on advanced private law areas, such as business associations, trusts and estates, and intellectual property.

scholarly journals Mutations Affecting Nerve Attachment of Caenorhabditis elegans

Genetics ◽  
2001 ◽  
Vol 157 (4) ◽  
pp. 1611-1622 ◽  
Author(s):  
Go Shioi ◽  
Michinari Shoji ◽  
Masashi Nakamura ◽  
Takeshi Ishihara ◽  
Isao Katsura ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Nerve Cord ◽  
Ventral Nerve Cord ◽  
Body Wall ◽  
The Body ◽  
Genetic Loci ◽  
Muscle Attachment ◽  
C Elegans ◽  
Ventral Cord ◽  
Excretory Canal

Abstract Using a pan-neuronal GFP marker, a morphological screen was performed to detect Caenorhabditis elegans larval lethal mutants with severely disorganized major nerve cords. We recovered and characterized 21 mutants that displayed displacement or detachment of the ventral nerve cord from the body wall (Ven: ventral cord abnormal). Six mutations defined three novel genetic loci: ven-1, ven-2, and ven-3. Fifteen mutations proved to be alleles of previously identified muscle attachment/positioning genes, mup-4, mua-1, mua-5, and mua-6. All the mutants also displayed muscle attachment/positioning defects characteristic of mua/mup mutants. The pan-neuronal GFP marker also revealed that mutants of other mua/mup loci, such as mup-1, mup-2, and mua-2, exhibited the Ven defect. The hypodermis, the excretory canal, and the gonad were morphologically abnormal in some of the mutants. The pleiotropic nature of the defects indicates that ven and mua/mup genes are required generally for the maintenance of attachment of tissues to the body wall in C. elegans.

Serotonin-induced nitric oxide production in the ventral nerve cord of the earthworm, Eisenia fetida

2001 ◽  
Vol 41 (2) ◽  
pp. 129-134 ◽  
Author(s):  
Yoshiichiro Kitamura ◽  
Yuichi Naganoma ◽  
Haruhito Horita ◽  
Hiroto Ogawa ◽  
Kotaro Oka
Keyword(s):  
Nitric Oxide ◽  
Nerve Cord ◽  
Eisenia Fetida ◽  
Ventral Nerve Cord ◽  
Nitric Oxide Production ◽  
Oxide Production
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