Development of the female gametophyte of Minuria cunninghamii (DC). Benth, Ccompositae)

1964 ◽  
Vol 12 (2) ◽  
pp. 152 ◽  
Author(s):  
GL Davis
Keyword(s):  
Comparative Study ◽  
Female Gametophyte ◽  
New South ◽  
Embryo Sac ◽  
Mature Embryo ◽  
Polygonum Type ◽  
South Wales ◽  
Significant Difference ◽  
Female Gametophyte Development ◽  
Two Populations

Minuria cunninghamii is widely distributed throughout the drier parts of Australia, and a comparative study was made of the female gametophyte development in two populations 300 miles apart in western New South Wales. In specimens collected 120 miles south of Menindee, the embryo sac was monosporic in origin and of the Polygonum type, whereas in those from Wanaaring it was usually bisporic and of the Allium type. No significant difference was found in mature embryo sacs from the two localities, although an unusual feature of both was the occurrence of vacuoles in the apices of the synergids.

scholarly journals Development of Female Gametophyte in Gladiolus italicus Miller (Iridaceae)

Caryologia ◽  
2021 ◽  
Vol 74 (3) ◽  
pp. 91-97
Author(s):  
Ciler Kartal ◽  
Nuran Ekici ◽  
Almina Kargacıoğlu ◽  
Hazal Nurcan Ağırman
Keyword(s):  
Light Microscopy ◽  
Female Gametophyte ◽  
Embryo Sac ◽  
Polygonum Type ◽  
Gametophyte Development ◽  
Embryo Sac Development ◽  
Secondary Nucleus ◽  
Microscopy Techniques ◽  
Female Gametophyte Development ◽  
First Time

In this study gynoecium, megasporogenesis, megagametogenesis and female gametophyte of Gladiolus italicus Miller were examined cytologically and histologically by using light microscopy techniques. Ovules of G. italicus are of anatropous, bitegmic and crassinucellate type. Embryo sac development is of monosporic Polygonum type. Polar nuclei fuse before fertilization to form a secondary nucleus near the antipodals. The female gametophyte development of G. italicus was investigated for the first time with this study.

scholarly journals Subtle Changes or Dramatic Perceptions of Air Pollution in Sydney during COVID-19

Environments ◽  
2021 ◽  
Vol 8 (1) ◽  
pp. 2
Author(s):  
Peter Brimblecombe ◽  
Yonghang Lai
Keyword(s):  
Air Pollution ◽  
Air Quality ◽  
New South ◽  
Human Mobility ◽  
Ground Level ◽  
Physical Reality ◽  
Social Perceptions ◽  
Search Terms ◽  
South Wales ◽  
Significant Difference

The COVID-19 pandemic made it critical to limit the spread of the disease by enforcing human isolation, restricting travel and reducing social activities. Dramatic improvements to air quality, especially NO2, have often characterised places under COVID-19 restrictions. Air pollution measurements in Sydney in April 2019 and during the lockdown period in April 2020 show reduced daily averaged NO2 concentrations: 8.52 ± 1.92 and 7.85 ± 2.92 ppb, though not significantly so (p1~0.15) and PM2.5 8.91 ± 4.94 and 7.95 ± 2.64 µg m−3, again a non-significant difference (p1~0.18). Satellite imagery suggests changes that parallel those at ground level, but the column densities averaged over space and time, in false-colour, are more dramatic. Changed human mobility could be traced in increasing times spent at home, assessed from Google Mobility Reports and mirrored in decreased traffic flow on a major road, suggesting compliance with the restrictions. Electricity demand for the State of New South Wales was low under lockdown in early April 2020, but it recovered rapidly. Analysis of the uses of search terms: bushfires, air quality, haze and air pollution using Google Trends showed strong links between bushfires and pollution-related terms. The smoke from bushfires in late 2019 may well have added to the general impression of improved air quality during lockdown, despite only modest changes in the ground level measurements. This gives hints that successful regulation of air quality requires maintaining a delicate balance between our social perceptions and the physical reality.

scholarly journals The mac1 Gene: Controlling the Commitment to the Meiotic Pathway in Maize

Genetics ◽  
1996 ◽  
Vol 142 (3) ◽  
pp. 1009-1020 ◽  
Author(s):  
William F Sheridan ◽  
Nadezhda A Avalkina ◽  
Ivan I Shamrov ◽  
Tatyana B Batyea ◽  
Inna N Golubovskaya
Keyword(s):  
Female Gametophyte ◽  
Embryo Sac ◽  
Flowering Plants ◽  
Normal Female ◽  
Ovule Development ◽  
Partial Sterility ◽  
Embryo Sac Formation ◽  
Female Gametophyte Development ◽  
Normal Meiosis ◽  
Pleiotropic Mutation

Abstract The switch from the vegetative to the reproductive pathway of development in flowering plants requires the commitment of the subepidermal cells of the ovules and anthers to enter the meiotic pathway. These cells, the hypodermal cells, either directly or indirectly form the archesporial cells that, in turn, differentiate into the megasporocytes and microsporocytes. We have isolated a recessive pleiotropic mutation that we have termed multiple archesporial cells1 (macl) and located it to the short arm of chromosome 10. Its cytological phenotype suggests that this locus plays an important role in the switch of the hypodermal cells from the vegetative to the meiotic (sporogenous) pathway in maize ovules. During normal ovule development in maize, only a single hypodermal cell develops into an archesporial cell and this differentiates into the single megasporocyte. In macl mutant ovules several hypodermal cells develop into archesporial cells, and the resulting megasporocytes undergo a normal meiosis. More than one megaspore survives in the tetrad and more than one embryo sac is formed in each ovule. Ears on mutant plants show partial sterility resulting from abnormalities in megaspore differentiation and embryo sac formation. The sporophytic expression of this gene is therefore also important for normal female gametophyte development.

Reproductive development in two species of Darwinia Rudge (Myrtaceae)

1969 ◽  
Vol 17 (2) ◽  
pp. 215 ◽  
Author(s):  
N Prakash
Keyword(s):  
Embryo Sac ◽  
Pollen Grains ◽  
Reproductive Development ◽  
Outer Zone ◽  
Mature Embryo ◽  
Globular Embryo ◽  
Primary Endosperm Nucleus ◽  
Oil Glands ◽  
Polygonum Type ◽  
History Of

In Darwinia the floral parts are differentiated in a "calyx-orolla-gynoeciumandroecium" sequence. In individual buds stages of microsporogenesis markedly precede corresponding stages of megasporogenesis. The anther is tetrasporangiate with all sporangia lying in one plane. The secretory tapetum is one- to three-layered within the same microsporangium and a large number of Ubisch bodies are formed. The anthers dehisce by minute lateral pores and an ingenious mechanism helps disperse the twocelled pollen grains. A basal placenta in the single loculus of the ovary bears four ovules in D. micropetala and two in D. fascicularis. In both species, however, only one ovule is functional after fertilization. The fully grown ovules are anatropous, crassinucellar, and bitegmic; the inner integument forms the micropyle. The parietal tissue is most massive at the completion of megasporogenesis but is progressively destroyed later. The embryo sac follows the Polygonum type of developnlent and when mature is five-nucleate, the three antipodals being ephemeral. Following fertilization, the primary endosperm nucleus divides before the zygote. Subsequent nuclear divisions in the endosperm mother cell are synchronous and lead to a free-nuclear endosperm which becomes secondarily cellular, starting from the micropylar end at the time the globular embryo assumes an elongated shape. Embryogeny is irregular and the mature embryo is straight with a massive radicle and a hypocotyl which terminates in two barely recognizable cotyledons. Sometimes the minute cotyledons are borne on a narrow neck-like extension of the hypocotyl. A suspensor is absent. Both integuments are represented in the seed coat and only the outer layer of the outer and the inner layer of the inner integuments, with their thick-walled tanniniferous cells, remain in the fully grown seed. The ovary wall is demarcated into an outer zone containing oil glands surrounded by cells containing a tannin-like substance and an inner zone of spongy parenchyma. In the fruit this spongy zone breaks down completely but the outer zone is retained. The two species of Darwinia, while closely resembling each other in their embryology, differ significantly from other Myrtaceae. However, no taxonomic conclusions are drawn at this stage, pending enquiry into the life history of other members of the tribe Chamaelaucieae.

scholarly journals Recent advances in understanding female gametophyte development

F1000Research ◽  
2018 ◽  
Vol 7 ◽  
pp. 804 ◽  
Author(s):  
Debra J Skinner ◽  
Venkatesan Sundaresan
Keyword(s):  
Cell Fate ◽  
Female Gametophyte ◽  
Cell Communication ◽  
Embryo Sac ◽  
Cell Types ◽  
Egg Cell ◽  
Male Gametes ◽  
Reproductive Unit ◽  
Genetic Mechanisms ◽  
Female Gametophyte Development

The haploid female gametophyte (embryo sac) is an essential reproductive unit of flowering plants, usually comprising four specialized cell types, including the female gametes (egg cell and central cell). The differentiation of these cells relies on spatial signals which pattern the gametophyte along a proximal-distal axis, but the molecular and genetic mechanisms by which cell identities are determined in the embryo sac have long been a mystery. Recent identification of key genes for cell fate specification and their relationship to hormonal signaling pathways that act on positional cues has provided new insights into these processes. A model for differentiation can be devised with egg cell fate as a default state of the female gametophyte and with other cell types specified by the action of spatially regulated factors. Cell-to-cell communication within the gametophyte is also important for maintaining cell identity as well as facilitating fertilization of the female gametes by the male gametes (sperm cells).

Ovule and Female Gametophyte Development in Fertile and Sterile Safflower Plants (Carthamus tinctorius L.)

1989 ◽  
Vol 37 (6) ◽  
pp. 519 ◽  
Author(s):  
J Carapetian ◽  
EA Rupert
Keyword(s):  
Cell Differentiation ◽  
Female Gametophyte ◽  
Embryo Sac ◽  
Carthamus Tinctorius ◽  
Gametophyte Development ◽  
Male Gametogenesis ◽  
Delayed Initiation ◽  
Rapid Elongation ◽  
Functional Megaspore ◽  
Female Gametophyte Development

Development of safflower ovules and female gametophytes was compared in fertile and genetically sterile F2 and backcross segregants from the cross between 'US-10' and '57-147' genotypes. Fertile plants formed normal anatropous ovules with eight-nucleate embryo sacs, typical of the angiosperms. One week before anthesis, the eight-nucleate embryo sac is well developed and undergoes rapid elongation and expansion during the 24 h prior to anthesis, accompanied by a doubling in length of the florets. Sterile plants also formed normal ovules, but apparently with a delayed initiation of meiosis which was subsequently arrested at Metaphase I. Embryo sacs did not form in sterile florets except for rare observations of uninucleate embryo sacs which began to degenerate before anthesis. The integumentary tapetum which normally developed upon completion of meiosis in fertile plants, was well developed during Prophase I of megasporogenesis in sterile plants. This observation suggests that cell differentiation and development of this nutritive jacket is basically controlled by the age of the ovules rather than initiated by appearance of the functional megaspore. Failure of both female and male gametogenesis seems to result from interaction of three independently segregating genes.

Effects of variable-intensity logging and the influence of habitat variables on the distribution of the Greater Glider Petauroides volans in montane forest, southeastern New South Wales

2000 ◽  
Vol 6 (1) ◽  
pp. 18 ◽  
Author(s):  
Rodney P. Kavanagh ◽  
Rodney P. Kavanagh
Keyword(s):  
New South ◽  
New South Wales ◽  
Basal Area ◽  
Environmental Variable ◽  
Variable Intensity ◽  
Usual Practice ◽  
South Wales ◽  
Arboreal Marsupials ◽  
Significant Difference ◽  
Before And After

Populations of arboreal marsupials were assessed in forests before and after logging at different levels of logging intensity to determine the sensitivity of these species to habitat disturbance. The logging treatments imposed were unlogged controls and two intensities of integrated logging for sawlogs and woodchips. The mean basal area of trees retained in logged blocks ranged from 83% to 35% of pre-logging levels. The objective of the study was to develop better methods for managing arboreal marsupials within the wood production forests of southeastern New South Wales. Seven species of arboreal marsupials were recorded during the study, but the Greater Glider Petauroides volans was the only species recorded in sufficient numbers for analysis (86% of all records). No significant differences were observed between the treatments in counts of the Greater Glider before and after logging. However, given the observed trend and an a priori expectation of a decline in numbers of this species following intensive logging, a one-tailed statistical test was applied which resulted in a significant difference at P = 0.08 for the contrast between the unlogged controls and the most intensively logged treatment. The existence of a threshold in logging intensity within the range of 21 % to 39% retention of tree basal area, below which numbers of the Greater Glider suffer a marked decline, was inferred on the basis of comparisons with the results of other studies. Factors other than logging were important in determining the distribution of the Greater Glider. Elevation, in particular, was a significant environmental variable, with Greater Gliders more likely to occur in forests above 845 m a.s.1. The presence and absence of particular tree species also influenced the distribution of the Greater Glider. Forests containing Manna Gum E. viminalis and Mountain Gum E. dalrympleana were highly preferred compared to forests with a high proportion of E. obliqua. The presence of E. cypellocarpa appeared to improve the quality of habitat for the Greater Glider in forests dominated by E. obliqua. This study has shown that Greater Glider populations can be maintained at or near pre-logging levels when at least 40% of the original tree basal area is retained thoughout logged areas and when the usual practice of retaining unlogged forest in riparian strips is applied.

57. GENOTYPING OF UROGENITAL CHLAMYDIA TRACHOMATIS IN REGIONAL NEW SOUTH WALES, AUSTRALIA

Sexual Health ◽  
2007 ◽  
Vol 4 (4) ◽  
pp. 306
Author(s):  
D. Mossman ◽  
C. Ooi ◽  
M. Loewenthal ◽  
M. Boyle
Keyword(s):  
Chlamydia Trachomatis ◽  
Older Patients ◽  
New South ◽  
Genotypic Variation ◽  
New South Wales ◽  
Genotype Frequency ◽  
Sexual Networks ◽  
Genotype Analysis ◽  
South Wales ◽  
Significant Difference

Background: Chlamydia Trachomatis is one of the most common sexually transmitted infections in Australia and world wide. This study was undertaken to map the frequency of Chlamydia genotypes in regional New South Wales (NSW), Australia, to explore the potential utility of genotype analysis in defining local sexual networks, and to investigate whether patterns of genotype frequency are correlated with demographic factors, including age and gender. Methods: We studied 204 urine samples infected with Chlamydia trachomatis, as determined by PCR analysis using the COBAS Amplicor system. Samples were collected from wide geographic area of regional New South Wales (Hunter, New England, Northern Rivers, South Eastern New South Wales). Sequencing and genotyping were performed after nested PCR of the omp1 gene. Results: Genotype E was found in 42.6% of infections, with genotypes F (23.5%) and G (16.7%) other common causes of infection. Mixed infection occurred in only 3 cases. There was no significant difference in genotype frequency based on gender or geographic location. There was a significant difference in gender frequency based on patient age, with older patients significantly more likely to demonstrate infection with genotype G (mean age (years) 23.7+/-7.29 sd, E: 21.7 +/-5.7 sd; G: 28.9; sd 10.18; p�=�0.022). Conclusions: There was no significant difference in genotype frequency in the various regions of New South Wales, suggesting genotype analysis is of limited use in defining sexual networks in regional NSW. The finding of a higher frequency of genotype G in older patients raises the possibility that genotypic variation may be driven by immune responses to genotypes that occur more frequently at a younger age. These results may have implications for the future design of a chlamydial vaccine.

Moult, Movements, Age and Sex Composition of Mountain Duck, Tadorna tadornoides, Banded at Lake George, N.S.W

1976 ◽  
Vol 3 (2) ◽  
pp. 173 ◽  
Author(s):  
JL McKean ◽  
LW Braithwaite
Keyword(s):  
Sex Ratio ◽  
Age Structure ◽  
New South ◽  
Sex Composition ◽  
South Wales ◽  
Two Samples ◽  
Significant Difference ◽  
Moult Migration ◽  
Lake George ◽  
Age And Sex

Two samples of mountain ducks totalling 1001 birds were trapped and banded at Lake George,N.S.W. A highly significant difference in age structure between the two samples, taken in January 1965 and in February 1970, may be related to major differences in rainfall for the year preceding each sample. The sex ratio was markedly biased in favour of females. Recoveries of birds were nearly all to the south and west and 300-700 km from the banding site. Fully 99 % of recoveries were in States other than New South Wales. Examination of one sample of 679 mountain ducks for moult of primary and secondary wing feathers showed that approximately one-third of the adults were moulting. It was concluded that the birds were possibly normal residents of the region in which most recoveries occurred, and that they make an annual moult migration to Lake George.

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