On the assembly and structural modulation of lens fiber junctions

1984 ◽  
Vol 42 ◽  
pp. 110-113
Author(s):  
E.L. Benedetti ◽  
I. Dunia ◽  
Do Ngoc Lien ◽  
O. Vallon ◽  
D. Louvard ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Natural History ◽  
Intercellular Junctions ◽  
Eye Lens ◽  
Membrane Domains ◽  
Functional Polymorphism ◽  
Lens Fiber ◽  
The Past ◽  
Structural Modulation ◽  
Biochemical Difference

In the eye lens emerging molecular and structural patterns apparently cohabit with the remnants of the past. The lens in a rather puzzling fashion sums up its own natural history and even transient steps of the differentiation are memorized. A prototype of this situation is well outlined by the study of the lenticular intercellular junctions. These membrane domains exhibit structural, biochemical and perhaps functional polymorphism reflecting throughout life the multiple steps of the differentiation of the epithelium into fibers and of the ageing process of the lenticular cells.The most striking biochemical difference between the membrane derived from the epithelium and from the fibers respectively, concerns the presence of the 26,000 molecular weight polypeptide (MP26) in the latter membranes.

Distribution of the main intrinsic polypeptide in lens fiber membrane domains

1984 ◽  
Vol 42 ◽  
pp. 122-125
Author(s):  
Paul G. FitzGerald ◽  
Joseph Horwitz ◽  
Dean Bok
Keyword(s):  
Intercellular Junctions ◽  
Membrane Domains ◽  
Lens Fiber ◽  
Fiber Membrane ◽  
Electron Microscopic ◽  
Lens Fiber Cell ◽  
Fiber Cells ◽  
Lens Fibers ◽  
Junctional Protein ◽  
Vertebrate Eye

The lens fiber cell of the vertebrate eye is a postmitotic, highly differentiated cell which is derived from the lens epithelium. Upon differentiation into lens fibers, the epithelium expresses a unique membrane protein (Main Intrinsic Polypeptide, MIP) with a molecular weight in excess of 26,000. These lens fiber cells are extraordinarily rich in intercellular junctions which can occupy up to 64% of the cell surface. Lens fiber junctions, frequently referred to as “gap junctions”, co-purify with MIP and it has therefore been suggested from biochemical evidence that MIP is a junctional protein.Electron microscopic immunoferritin studies in which rabbit anti-bovine MIP antiserum was incubated with isolated bovine lens fiber membranes have shown that MIP is present in abundance in pentalaminar profiles conventionally regarded as lens junctions (Figure 1).

Calmodulin-mediated gating of lens gap junction channels in vesicles

1984 ◽  
Vol 42 ◽  
pp. 134-137
Author(s):  
Camillo Peracchia ◽  
Stephen J. Girsch
Keyword(s):  
Gap Junctions ◽  
Freeze Fracture ◽  
Orthogonal Arrays ◽  
Eye Lens ◽  
Lens Fiber ◽  
Cell Coupling ◽  
Particle Spacing ◽  
Fiber Cells ◽  
Gap Junction Channels ◽  
Communicating Junctions

The fiber cells of eye lens communicate directly with each other by exchanging ions, dyes and metabolites. In most tissues this type of communication (cell coupling) is mediated by gap junctions. In the lens, the fiber cells are extensively interconnected by junctions. However, lens junctions, although morphologically similar to gap junctions, differ from them in a number of structural, biochemical and immunological features. Like gap junctions, lens junctions are regions of close cell-to-cell apposition. Unlike gap junctions, however, the extracellular gap is apparently absent in lens junctions, such that their thickness is approximately 2 nm smaller than that of typical gap junctions (Fig. 1,c). In freeze-fracture replicas, the particles of control lens junctions are more loosely packed than those of typical gap junctions (Fig. 1,a) and crystallize, when exposed to uncoupling agents such as Ca++, or H+, into pseudo-hexagonal, rhombic (Fig. 1,b) and orthogonal arrays with a particle-to-particle spacing of 6.5 nm. Because of these differences, questions have been raised about the interpretation of the lens junctions as communicating junctions, in spite of the fact that they are the only junctions interlinking lens fiber cells.

IV.—On the Fossil Sirenia in the British Museum (Natural History), Cromwell Road, S.W.

1885 ◽  
Vol 2 (9) ◽  
pp. 412-425
Author(s):  
Henry Woodward
Keyword(s):  
Natural History ◽  
British Museum ◽  
The Past

Among the vast additions which, during the past five years, have been made to the palæontological collections in the British Museum (Natural History), none probably possess greater interest to the naturalist and comparative anatomist than the remains of the very remarkable group of aquatic phytophagous mammals known as the Sirenia, of which the “Manatee” and the “Dugong” are the living representatives.

scholarly journals Using insect natural history collections to study global change impacts: challenges and opportunities

2018 ◽  
Vol 374 (1763) ◽  
pp. 20170405 ◽  
Author(s):  
Heather M. Kharouba ◽  
Jayme M. M. Lewthwaite ◽  
Rob Guralnick ◽  
Jeremy T. Kerr ◽  
Mark Vellend
Keyword(s):  
Natural History ◽  
Global Change ◽  
Global Changes ◽  
Genomic Information ◽  
Theme Issue ◽  
The Past ◽  
Natural History Collections ◽  
Global Change Research ◽  
Challenges And Opportunities

Over the past two decades, natural history collections (NHCs) have played an increasingly prominent role in global change research, but they have still greater potential, especially for the most diverse group of animals on Earth: insects. Here, we review the role of NHCs in advancing our understanding of the ecological and evolutionary responses of insects to recent global changes. Insect NHCs have helped document changes in insects' geographical distributions, phenology, phenotypic and genotypic traits over time periods up to a century. Recent work demonstrates the enormous potential of NHCs data for examining insect responses at multiple temporal, spatial and phylogenetic scales. Moving forward, insect NHCs offer unique opportunities to examine the morphological, chemical and genomic information in each specimen, thus advancing our understanding of the processes underlying species’ ecological and evolutionary responses to rapid, widespread global changes. This article is part of the theme issue ‘Biological collections for understanding biodiversity in the anthropocene’.

III.—A Synopsis of the Remains of Ganoid Fishes from the Cambridge Greensand

1895 ◽  
Vol 2 (5) ◽  
pp. 207-214 ◽  
Author(s):  
Arthur Smith Woodward
Keyword(s):  
Natural History ◽  
British Museum ◽  
Detailed Comparison ◽  
Present Writer ◽  
The Past ◽  
Private Collection ◽  
Definition Of

The remains of fishes discovered in the Cambridge Greensand are all very fragmentary, and have not hitherto been subjected to the detailed comparison with other Cretaceous Ichthyolites which their interesting stratigraphical position renders desirable. Many specimens, however, are capable of at least generic determination, while many others are sufficiently characteristic fragments for the definition of the species. The present writer has thus been much interested during the past few years in studying collections of these fossils, and the following notes embody some of the results in reference to the ganoid fishes. The British Museum (Natural History) having recently acquired the collection made from the Cambridge Greensand by Mr. Thomas Jesson, F.G.S., nearly all the known species are now represented here; but the writer has also availed himself of the privilege of making use of the fine series in the Woodwardian Museum, Cambridge, and the Philosophical Society's Museum, York, thanks to the kindness of Professor McKenny Hughes, Mr. Henry Woods, and Mr. H. M. Platnauer. Mr. James Carter, M.R.C.S., has also kindly lent some Pycnodont jaws from his private collection

Historical Records and Collections

2019 ◽  
pp. 18-33
Author(s):  
Emily W. B. Russell Southgate
Keyword(s):  
Natural History ◽  
Historical Data ◽  
Historical Documents ◽  
Historical Records ◽  
The Past ◽  
Natural History Collections ◽  
Government Documents ◽  
Historical Photographs ◽  
General Explanation

This chapter introduces the use of historical documents and other forms of information that depend on written explanation, such as natural history collections and historical photographs. After a general explanation of the unique values of these data for establishing historical baselines and trajectories, it gives a brief introduction to the methods used to assess the validity of the sources, including consideration of various biases that are integral to written documents. These include a consideration of scale. The chapter then describes a variety of sources, including historical data, maps, photographs, government documents, and plant and animal collections, with examples of how each has been used to establish some condition or process in the past.

scholarly journals A 21st Century Vision for Neotropical Snake Systematics

2018 ◽  
Vol 1 (1) ◽  
pp. 58
Author(s):  
Robert Alexander Pyron
Keyword(s):  
Species Richness ◽  
Natural History ◽  
Global Change ◽  
South America ◽  
Ecosystem Function ◽  
Museum Specimens ◽  
Fine Grained ◽  
The Past ◽  
The Caribbean ◽  
Recent Synthesis

We live in an unprecedented age for systematics and biodiversity studies. Ongoing global change is leading to a future with reduced species richness and ecosystem function (Pereira, Navarro, & Martins, 2012). Yet, we know more about biodiversity now than at any time in the past. For squamates in particular, we have range maps for all species (Roll et al., 2017), phylogenies containing estimates for all species (Tonini, Beard, Ferreira, Jetz, & Pyron, 2016), and myriad ecological and natural-history datasets for a large percentage of species (Meiri et al., 2013; Mesquita et al., 2016). For neotropical snakes, a recent synthesis of museum specimens and verified localities offers a fine-grained perspective on their ecogeographic distribution in Central and South America, and the Caribbean (Guedes et al., 2018).

scholarly journals Looking Back for the Future: Utilizing Sawfish Saws from Natural History Collections to Conserve the Critically Endangered Largetooth Sawfish (Pristis pristis)

2018 ◽  
Vol 2 ◽  
pp. e25806
Author(s):  
Annmarie Fearing ◽  
Kelcee Smith ◽  
Tonya Wiley ◽  
Jeff Whitty ◽  
Kevin Feldheim ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Natural History ◽  
Mitochondrial Control Region ◽  
Genetic Bottleneck ◽  
Critically Endangered ◽  
Past Century ◽  
Term Survival ◽  
Tissue Samples ◽  
The Past ◽  
Natural History Collections

The Critically Endangered (International Union for Conservation of Nature) largetooth sawfish, Pristispristis, was historically distributed in the tropical Pacific, Atlantic and Indian Oceans. Today, ‘viable’ populations are largely limited to northern Australia. Populations that have suffered from drastic declines in abundance, such as those experienced by P.pristis, are typically at risk of having reduced, or low, levels of genetic diversity. Previous research found that P.pristis in Australia have experienced a genetic bottleneck, but it is unclear whether this bottleneck is the result of contemporary declines over the last century, or if it is the result of historic processes. A direct way to assess whether this genetic bottleneck occurred relatively recently is to compare levels of genetic diversity in contemporary and historic populations. Sawfish saws that were taken as trophies over the past century can now be found in natural history collections around the world and can provide DNA from past sawfish populations. We collected tissue samples from 150 dried P.pristis saws found in both private and public natural history collections. Because DNA from natural history specimens tends to be highly degraded, we targeted ten small DNA fragments, ~150 base pairs each, to amplify and sequence the entire mitochondrial control region. These data will provide important baseline information about P.pristis that can be used to quantify any loss of genetic diversity over the past ~100 years and assess their long-term survival potential. If the levels of genetic diversity in contemporary populations are severely reduced from those of past populations, protecting remaining genetic diversity within and between viable populations should be a priority in conservation plans.

Typifications and taxonomic notes for Veronica subgen. Pseudolysimachium (Plantaginaceae) based on material from the Hungarian Natural History Museum Budapest (BP)

Phytotaxa ◽  
2017 ◽  
Vol 331 (1) ◽  
pp. 35 ◽  
Author(s):  
DIRK C. ALBACH ◽  
DÁNIEL PIFKÓ ◽  
ZOLTÁN BARINA
Keyword(s):  
Molecular Markers ◽  
Natural History ◽  
Natural History Museum ◽  
Northern Eurasia ◽  
Southeastern Europe ◽  
Important Species ◽  
History Museum ◽  
The Past ◽  
Dry Steppe ◽  
Hungarian Natural History Museum

Veronica subgen. Pseudolysimachium is a group of 30 species ranging across northern Eurasia in various open habitats from dry steppe to swamps. It includes several horticulturally important species that have been crossed in the past. As such, it exemplifies a group with long taxonomic tradition, exemplified by more than 600 valid names, which also indicates its variability. In the process of identifying the evolutionary important units, molecular markers have started to help immensely. However, assigning names to identified significant groups of populations has been hindered by problems in typification. Here, we try to alleviate the problem for the taxa in southeastern Europe, which have been analyzed rigorously using AFLP fingerprints in the past, by lectotypifying 11 names and neotypifying four names, mostly based on specimens found in the Hungarian Natural History Museum Budapest (BP). This allowed revising Veronica barrelieri with its three subspecies and synonyms.

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