CHROMOSOME NUMBERS OF SOME NORTH AMERICAN MIRIDS (HETEROPTERA: MIRIDAE)

1974 ◽  
Vol 16 (2) ◽  
pp. 251-256 ◽  
Author(s):  
A. E. Akingbohungbe
Keyword(s):  
North American ◽  
Chromosome Numbers ◽  
Probable Mechanism ◽  
Chromosomal Change ◽  
New Information ◽  
Existing Data

Data are presented on the chromosome numbers (2n) of some eighty species of Miridae. The new information is combined with existing data on some Palearctic and Ethiopian species and discussed. From it, it is suggested that continued reference to 2n = 32A + X + Y as basic mirid karyotype should be avoided and that contrary to earlier suggestions, agmatoploidy rather than polyploidy is a more probable mechanism of numerical chromosomal change.

CYTOTAXONOMY, PHYLOGENY, AND CANADIAN DISTRIBUTION OF CIRSIUM UNDULATUM AND CIRSIUM FLODMANII

1961 ◽  
Vol 39 (1) ◽  
pp. 21-33 ◽  
Author(s):  
C. Frankton ◽  
R. J. Moore
Keyword(s):  
North American ◽  
Chromosome Numbers ◽  
World Wide ◽  
North American Species ◽  
Base Number ◽  
Total Length ◽  
The World ◽  
Cirsium Undulatum

The morphology and specific differences of Cirsium undulatum (Nutt.) Spreng. and of C. flodmanii (Rydb.) Arthur are described and their Canadian distributions are reported in detail. The chromosome numbers are C. undulatum f. undulatum and f. album Farwell, 2n = 26; C. flodmanii f. flodmanii and f. albiflorum D. Löve, 2n = 22. The origin of four North American species of Cirsium that do not follow the world-wide base number 17 is discussed; it is postulated that reduction in number has occurred by translocations. The chromosomes of species with reduced numbers are larger than those of the unreduced species but the total length of the chromosomes of both groups is approximately the same.

scholarly journals Sleep, Memory & Brain Rhythms

Daedalus ◽  
2015 ◽  
Vol 144 (1) ◽  
pp. 67-82 ◽  
Author(s):  
Brendon O. Watson ◽  
György Buzsáki
Keyword(s):  
Brain Function ◽  
Scientific Community ◽  
Knowledge Retention ◽  
Brain Functioning ◽  
Brain Rhythms ◽  
Homeostatic Mechanism ◽  
New Information ◽  
The Brain ◽  
Oscillatory Rhythm ◽  
Existing Data

Sleep occupies roughly one-third of our lives, yet the scientific community is still not entirely clear on its purpose or function. Existing data point most strongly to its role in memory and homeostasis: that sleep helps maintain basic brain functioning via a homeostatic mechanism that loosens connections between overworked synapses, and that sleep helps consolidate and re-form important memories. In this review, we will summarize these theories, but also focus on substantial new information regarding the relation of electrical brain rhythms to sleep. In particular, while REM sleep may contribute to the homeostatic weakening of overactive synapses, a prominent and transient oscillatory rhythm called “sharp-wave ripple” seems to allow for consolidation of behaviorally relevant memories across many structures of the brain. We propose that a theory of sleep involving the division of labor between two states of sleep–REM and non-REM, the latter of which has an abundance of ripple electrical activity–might allow for a fusion of the two main sleep theories. This theory then postulates that sleep performs a combination of consolidation and homeostasis that promotes optimal knowledge retention as well as optimal waking brain function.

Chromosome numbers and sexual compatibility in North America of Rorippa sylvestris (Cruciferae)

1984 ◽  
Vol 62 (3) ◽  
pp. 575-580 ◽  
Author(s):  
Gerald A. Mulligan ◽  
Derek B. Munro
Keyword(s):  
North America ◽  
North American ◽  
Chromosome Numbers ◽  
Interspecific Hybrid ◽  
Field Observations ◽  
Sexual Compatibility ◽  
Intraspecific Crossing

Tetraploid (2n = 32), pentaploid (2n = 40), and hexaploid (2n = 48) plants of Rorippa sylvestris (L.) Besser (Cruciferae) and a natural pentaploid (2n = 40) interspecific hybrid, R. sylvestris × R. palustris (L.) Besser, are recorded for North America. These counts are compared with published information on European plants. Tetraploids are most common in Europe (68 vs. 20%), whereas hexaploids are most common in North America (65 vs. 29%). Although self-incompatible R. sylvestris rarely sets seed in nature, indicating that plants within most sites are genetically the same clone, intraspecific crossing data, chromosome information, and field observations indicate that North American R. sylvestris results from the vegetative introduction of many different genotypes.

CHROMOSOME NUMBERS FOR NORTH AMERICAN EUPHORBIACEAE

1975 ◽  
Vol 62 (5) ◽  
pp. 494-500 ◽  
Author(s):  
Lowell E. Urbatsch ◽  
John D. Bacon ◽  
Ronald L. Hartman ◽  
Marshall C. Johnston ◽  
Thomas J. Watson ◽  
...  
Keyword(s):  
North American ◽  
Chromosome Numbers

Chromosome numbers of 15 North American bumble bee species (Hymenoptera, Apidae, Bombini)

1983 ◽  
Vol 25 (1) ◽  
pp. 26-29
Author(s):  
Robin E. Owen
Keyword(s):  
Chromosome Number ◽  
North American ◽  
Chromosome Numbers ◽  
Bumble Bees ◽  
Bumble Bee ◽  
Morphological Divergence ◽  
Chromosome Counts ◽  
Monophyletic Origin ◽  
The Social

Chromosome counts were obtained for 14 Bombus Latr. species (the social bumble bees) belonging to four subgenera and for one Psithyrus Lep. species (the social parasitic bumble bees). In Bombus the haploid numbers were consistent within each subgenus and there was variation between subgenera; the subgenera Bombus s.s. and Pyrobombus have n = 18, while Separatobombus and Cullumanobombus have n = 19. Thus considerable morphological divergence between subgenera is often, but not always, paralleled by divergence in chromosome number. Psithyrus ashtoni has n = 25, higher than all Bombus species yet examined. This provides support for the monophyletic origin of Psithyrus, but the high n is not expected if eusociality selects for increase in chromosome number.

The cytology of Brachycome. I. The subgenus Eubrachycome: A general survey

1970 ◽  
Vol 18 (1) ◽  
pp. 99 ◽  
Author(s):  
S Smith-White ◽  
CR Carter ◽  
HM Stace
Keyword(s):  
Chromosome Number ◽  
Chromosome Numbers ◽  
Base Number ◽  
Undescribed Species ◽  
General Survey ◽  
Chromosome Races ◽  
Chromosomal Change ◽  
Cytological Data ◽  
Wide Range ◽  
Annual Habit

Chromosome number determinations and cytological observations are reported for 37 recognized taxonomic species and varieties, and for a number of undescribed species and chromosome races in Eubrachycome. Additionally, chromosome numbers are reported for six species of Metabrachycome and two species of related genera. A wide range of numbers has been found. It is inferred that x = 9 is the primitive base number in the group. Eubrachycome has used various modes of chromosomal change, including polyploidy, amphidiploidy, decrease in base number, and the establishment of B. chromosomes. The present taxonomy of the group requires revision, taking into account cytological data. Primitive Eubrachycome was probably a mesic perennial. The evolution of desert species has involved reduction in chromosome number and the adoption of the annual habit, but other methods of desert adaptation have been available. Many species are chromosomally unstable, and may have been subject to catastrophic selection.

The chromosome numbers of five North American and European leech species

1987 ◽  
Vol 65 (3) ◽  
pp. 681-684 ◽  
Author(s):  
Ronald W. Davies ◽  
R. N. Singhal
Keyword(s):  
Chromosome Number ◽  
North American ◽  
Chromosome Numbers ◽  
Chromosome Evolution ◽  
Chromosome Counts ◽  
Prophase I ◽  
Metaphase I

Chromosome counts were obtained for four glossiphoniid species belonging to three genera (Glossiphonia, Theromyzon, Placobdella) and for one erpobdellid species (Dina lineata) of freshwater leeches. Theromyzon rude, which has a Palaearctic distribution, had seven bivalents at prophase I and metaphase I, while the Holarctic T. tessulatum had eight bivalents, giving diploid chromosome numbers of 14 and 16, respectively. Placobdella papillifera from Alberta had a chromosome number of 2n = 24 and Glossiphonia complanata from Alberta and England had chromosome counts of 2n = 28. At prophase I and metaphase I nine bivalents occurred in the majority of the nuclei of Dina lineata. These findings are discussed in relation to the chromosome evolution and phylogenetic schemes proposed by previous authors.

Methods, Mounds, and Missions: New Contributions to Florida Archaeology

2021 ◽  
Author(s):  
Jeffrey M. Mitchem
Keyword(s):  
Florida Archaeology ◽  
New Information ◽  
Existing Data

Offering innovative ways of looking at existing data, as well as compelling new information, about Florida’s past, this volume updates current archaeological interpretations and demonstrates the use of new and improved tools to answer larger questions.

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