Reproductive and Genetic-Studies With a Laboratory Colony of the Dasyurid Marsupial Sminthopsis-Crassicaudata

1989 ◽  
Vol 37 (3) ◽  
pp. 207 ◽  
Author(s):  
JH Bennett ◽  
WG Breed ◽  
DL Hayman ◽  
RM Hope
Keyword(s):  
Reproductive Biology ◽  
Meiotic Chromosome ◽  
Litter Production ◽  
Genetic Studies ◽  
Adult Weight ◽  
Sminthopsis Crassicaudata ◽  
Laboratory Colony ◽  
Marked Disparity ◽  
Marsupial Species ◽  
High Level

The fat-tailed dunnart, Sminthopsis crassicaudata, is a small insectivorous dasyurid (adult weight about 16 g) widely distributed in Australia. A laboratory colony of this marsupial, which has been built up over many years, is providing material for studies of dasyurid reproductive biology and genetics. In the area of reproductive biology, we have found a marked disparity in the age of maturation between the two sexes, and we are currently studying certain aspects of spermatogenesis, sperm transport, fertilisation and early embryonic development. Genetical studies have revealed large differences between the sexes in autosomal linkage values and meiotic chromosome behaviour. In females, we have observed very limited intrachromosomal recombination and this is reflected in the distal localisation of chiasmata on the autosomes. Extreme localisation of chiasmata has not hitherto been found in a mammal, and it will be interesting to see how widely it occurs in other marsupial species. The genetical and cytological findings lead to a number of predictions that are being tested in further experimental work with the colony. Although we have been able to raise litter production to a high level, the very variable and unpredictable nature of male reproductive performance currently limits the wider use of the S. crassicaudata colony. It is clear, however, that this dasyurid has the potential to become a very useful laboratory marsupial and that it will be especially valuable for comparative biomedical studies.

INHERITANCE OF RESISTANCE TO NET BLOTCH IN BARLEY. I. FACTORS AFFECTING THE PENETRANCE AND EXPRESSIVITY OF GENE(S) CONDITIONING HOST RESISTANCE

1969 ◽  
Vol 11 (3) ◽  
pp. 587-591 ◽  
Author(s):  
T. N. Khan
Keyword(s):  
Environmental Conditions ◽  
Net Blotch ◽  
Host Reaction ◽  
Susceptible Parent ◽  
Breeding Programs ◽  
Genetic Studies ◽  
Factors Affecting ◽  
Drechslera Teres ◽  
Resistant Varieties ◽  
High Level

Variability in the host-reaction of barley to infection by Drechslera teres was examined in the parents and progeny of selected crosses under different environmental conditions of testing.The Ethiopian variety C.I. 5791 exhibits a consistently high level of resistance under a range of environmental conditions, which is in contrast to the Manchurian variety C.I. 2330. The sensitivity of the genes for resistance possessed by these varieties to environmental modifications is considered to depend upon their respective genetic backgrounds. Furthermore, variability of host reaction in the progeny of these resistant varieties was shown to be influenced by the genetic background of the susceptible parent used.The implications of these findings in the conduct and interpretation of genetic studies and in backcross breeding programs is discussed.

Genetic structure of Gahnia radula (Cyperaceae), a key sedge for revegetation

2017 ◽  
Vol 65 (2) ◽  
pp. 128
Author(s):  
Alex Arnold ◽  
Andrea Kodym ◽  
Nancy M. Endersby-Harshman ◽  
John Delpratt ◽  
Ary A. Hoffmann
Keyword(s):  
Genetic Variation ◽  
Adaptive Potential ◽  
Genetic Studies ◽  
Potential Source ◽  
Landscape Processes ◽  
Disturbed Areas ◽  
Eastern Australia ◽  
Genetic Patterns ◽  
Source Populations ◽  
High Level

Genetic studies can help guide effective ecological restoration by identifying potential source populations that contain the genetic variation necessary for adaptive potential, based on past landscape processes. Here we investigate genetic patterns in Gahnia radula (R.Br.) Benth., a sedge from south-eastern Australia that has potential for revegetation of disturbed areas. We developed microsatellite markers for this species and used them to show that it propagates mostly in a clonal manner. Levels of genetic variability differed between populations and the spatial scale of this variability within these populations is identified. A population used in recent restoration efforts and which sets seed has a particularly high level of variability. Recommendations are developed for sourcing material when using this sedge for revegetation.

scholarly journals Marsupial chromosome DNA content and genome size assessed from flow karyotypes: invariable low autosomal GC content

2018 ◽  
Vol 5 (8) ◽  
pp. 171539 ◽  
Author(s):  
Fumio Kasai ◽  
Patricia C. M. O'Brien ◽  
Jorge C. Pereira ◽  
Malcolm A. Ferguson-Smith
Keyword(s):  
Genome Size ◽  
Dna Content ◽  
Chromosome Painting ◽  
Gc Content ◽  
Tammar Wallaby ◽  
Individual Chromosome ◽  
Tasmanian Devil ◽  
Marsupial Species ◽  
Cross Species Chromosome Painting ◽  
High Level

Extensive chromosome homologies revealed by cross-species chromosome painting between marsupials have suggested a high level of genome conservation during evolution. Surprisingly, it has been reported that marsupial genome sizes vary by more than 1.2 Gb between species. We have shown previously that individual chromosome sizes and GC content can be measured in flow karyotypes, and have applied this method to compare four marsupial species. Chromosome sizes and GC content were calculated for the grey short-tailed opossum (2 n = 18), tammar wallaby (2 n = 16), Tasmanian devil (2 n = 14) and fat-tailed dunnart (2 n = 14), resulting in genome sizes of 3.41, 3.31, 3.17 and 3.25 Gb, respectively. The findings under the same conditions allow a comparison between the four species, indicating that the genomes of these four species are 1–8% larger than human. We show that marsupial genomes are characterized by a low GC content invariable between autosomes and distinct from the higher GC content of the marsupial × chromosome.

scholarly journals Microsatellites Cross-Species Amplification across Some African Cichlids

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Etienne Bezault ◽  
Xavier Rognon ◽  
Karim Gharbi ◽  
Jean-Francois Baroiller ◽  
Bernard Chevassus
Keyword(s):  
Microsatellite Markers ◽  
Oreochromis Niloticus ◽  
Molecular Genetic ◽  
Point Of View ◽  
Genetic Studies ◽  
African Cichlid ◽  
Wide Range ◽  
The Mean ◽  
High Level ◽  
African Cichlids

The transfer of the genomic resources developed in the Nile tilapia, Oreochromis niloticus, to other Tilapiines sensu lato and African cichlid would provide new possibilities to study this amazing group from genetics, ecology, evolution, aquaculture, and conservation point of view. We tested the cross-species amplification of 32 O. niloticus microsatellite markers in a panel of 15 species from 5 different African cichlid tribes: Oreochromines (Oreochromis, Sarotherodon), Boreotilapiines (Tilapia), Chromidotilapines, Hemichromines, and Haplochromines. Amplification was successfully observed for 29 markers (91%), with a frequency of polymorphic (P95) loci per species around 70%. The mean number of alleles per locus and species was 3.2 but varied from 3.7 within Oreochromis species to 1.6 within the nontilapia species. The high level of cross-species amplification and polymorphism of the microsatellite markers tested in this study provides powerful tools for a wide range of molecular genetic studies within tilapia species as well as for other African cichlids.

Genetically-Determined Variation of Pelage Color and Reflectance in Natural and Laboratory Populations of the Marsupial Sminthopsis-Crassicaudata (Gould)

1988 ◽  
Vol 36 (4) ◽  
pp. 441 ◽  
Author(s):  
RM Hope ◽  
GK Godfrey
Keyword(s):  
Selective Advantage ◽  
South Central ◽  
Upper Limit ◽  
Sminthopsis Crassicaudata ◽  
Laboratory Colony ◽  
Laboratory Populations ◽  
Pelage Color ◽  
Desert Areas ◽  
Central Australia ◽  
Genetically Determined

A study of variation in dorsal pelage colour and reflectance of the dasyurid marsupial, Sminthopsis crassicaudata, has been based on animals captured from widely scattered areas in south-central Australia, and on a laboratory colony of this species. Measurements on the degree of resemblance between relatives gave heritability estimates of pelage reflectance close to the theoretical upper limit of unity. Measurements on the reflectance of animals captured from the wild revealed a geographical cline, with reflectance decreasing (animals becoming darker) with increasing southerly latitude. The higher reflectance (paler coloured) animals were found to inhabit the northern desert areas. We suggest that this cline results from a selective advantage enjoyed by animals whose dorsal pelage colour makes them relatively inconspicuous in their habitat to nocturnal preditors.

Cross-species amplification and characterization of microsatellite loci in Pinus mugo Turra

Biologia ◽  
2013 ◽  
Vol 68 (4) ◽  
Author(s):  
Konrad Celiński ◽  
Ewa Pawlaczyk ◽  
Aleksandra Wojnicka-Półtorak ◽  
Ewa Chudzińska ◽  
Wiesław Prus-Głowacki
Keyword(s):  
Microsatellite Markers ◽  
Polymorphic Information Content ◽  
Pinus Mugo ◽  
Genetic Studies ◽  
Transfer Rates ◽  
Isolation And Characterization ◽  
Nuclear Microsatellite ◽  
European Mountain ◽  
High Level

AbstractPinus mugo (dwarf mountain pine) is an important component of European mountain ecosystems. However, little is known about the present genetic structure and population differentiation of this species at the DNA level, possibly due to a lack of nuclear microsatellite markers (SSR) developed for Pinus mugo. Therefore in this study we transferred microsatellite markers originally developed for Pinus sylvestris and Pinus taeda to Pinus mugo. This cross-species amplification approach is much faster and less expensive than isolation and characterization of new microsatellite markers. The transfer rates from the source species to Pinus mugo were moderately low (26%). There were no differences in microsatellite repeat motifs between the source species and Pinus mugo. Nuclear microsatellite markers successfully transferred to Pinus mugo can be applied to various genetic studies on this species, due to the high level of their polymorphism and high value of polymorphic information content.

Photoperiod and some other factors affecting reproduction in female Sminthopsis crassicaudata (Gould) (Marsupialia : Dasyuridae) in captivity

1978 ◽  
Vol 26 (3) ◽  
pp. 449 ◽  
Author(s):  
MJ Smith ◽  
JH Bennett ◽  
CM Chesson
Keyword(s):  
Widespread Species ◽  
Factors Affecting ◽  
Factors Influencing ◽  
Pathological Conditions ◽  
Sminthopsis Crassicaudata ◽  
Laboratory Colony ◽  
In Captivity ◽  
Biochemical Variation ◽  
To Come ◽  
Short Days

In central and southern Australia, S. crassicaudata is a widespread species which shows morphological and biochemical variation throughout its range. A laboratory colony was established from wild-caught animals from central, southern and south-eastern populations. The origin of wild-caught females or the parentage of laboratory-bred females did not affect their response to any of the investigated factors influencing reproduction. Very few females produced litters after they had reached 30 months of age. The colony was maintained for nearly 10 years in one artificially illuminated room. The lighting schedule was usually 16L : 8D, but at approximately 6-monthly intervals the animals were subjected to 3 weeks of 8L : 16D. Significantly more litters were born in pairings that had experienced short days than in those continuously exposed to long days. Oestrous cycles ceased in the 8L : 16D periods and resumed at about 20-30 days after the onset of 16L : 8D in many females, although some took longer to come into oestrus. Two of 27 females did not come into oestrus within 88 days, and, of the 25 females that came into oestrus, five did not ovulate. Pathological conditions in the reproductive system were rare. Most litters were born within the first 6 weeks of pairs being formed. Females which had produced one litter were more likely to produce a second litter when returned to the father of their first litter than when caged with a different male. When two females were caged with one male, one or occasionally both females produced a litter. Breeding in response to onset of long days is not consistent with the opportunistic breeding of many desert animals.

scholarly journals Study genetic diversity in maize inbreds and improved hybrid vigor in hybrids produce to determine commercial hybrids in Iraq

2015 ◽  
Vol 5 (3) ◽  
pp. 728-731
Author(s):  
Ziyad A. Abed
Keyword(s):  
Genetic Diversity ◽  
Genetic Distance ◽  
Rapd Markers ◽  
Field Experiments ◽  
Random Amplified Polymorphic Dna ◽  
Hybrid Vigor ◽  
Breeding Programs ◽  
Genetic Studies ◽  
Maize Inbreds ◽  
High Level

 A field experiments was conducted in greenhouse to determinate the genetic diversity among 7 genotypes from maize(4 inbreds and 3hybrids) by using molecular markers with Random Amplified polymorphic DNA(RAPD),that shown high level of polymorphism among genotypes of maize ,where the percentage of polymorphism ranged from(66%) and (83.33%) the highest number of polymorphism band (16) and size fragment ranged between (3800 bp) with the primer ( Bnlg 1185 ) and the lowest 180 with the primer( Bnlg 1464).The genetic distance value ranged between (0.3451) and (0.6534) ,where the lowest genic distance between (k1 and k2),while the highest genetic distance between(k4) and (k3xk4).In this study RAPD markers were shown to be powerful to detect genetic diversity and provided us high polymorphism values within genotypes of maize ,also we can conclude for useful those primers for genetic studies in plant breeding programs for developing synthetic cultivars or improved inbreds of maize. 

Genetic control of meiotic chromosome pairing in tetraploid Agropyron elongatum. I. Pattern of pairing in natural and induced tetraploids and in F1 triploid hybrids

1986 ◽  
Vol 28 (5) ◽  
pp. 783-788 ◽  
Author(s):  
A. Charpentier ◽  
M. Feldman ◽  
Y. Cauderon
Keyword(s):  
Control System ◽  
Genetic Control ◽  
Chromosome Pairing ◽  
Meiotic Chromosome ◽  
Agropyron Elongatum ◽  
Homologous Group ◽  
Meiotic Chromosome Pairing ◽  
Random Pairing ◽  
Expected Values ◽  
High Level

Meiotic chromosome pairing was studied in natural and induced tetraploid Agropyron elongatum, as well as in triploid hybrids between natural tetraploid and diploid cytotypes. The natural tetraploids showed a highly regular, diploid-like pairing, while the induced ones showed an average of two to three multivalents per cell. A high level of pairing was exhibited by the triploid hybrids, 4.15 bivalents and 2.82 trivalents per cell, supporting the assumption that the natural tetraploid is of an autoploid origin. Frequencies of meiotic configurations of the induced tetraploid and of the F1 triploid hybrids deviated significantly from the expected values based on a model assuming random pairing within one homologous group in autoploids: the observed data were characterized by fewer multivalents than expected, indicating a tendency towards bivalentization. This tendency is fully realized in the natural tetraploid. The presence of a pairing-control system in these autoploids, most probably a genetic one, that determines bivalent rather than multivalent pairing is suggested.Key words: Agropyron, pairing, bivalentization, tetraploid, multivalents.

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