The presence of synaptic and chromosome disjunction mutants in Cenchrus ciliaris (Poaceae: Paniceae)

Bothalia ◽  
1999 ◽  
Vol 29 (2) ◽  
pp. 327-334 ◽  
Author(s):  
N. C. Visser ◽  
J. J. Spies ◽  
H. J. T. Venter
Keyword(s):  
Environmental Factors ◽  
Geographical Distribution ◽  
High Temperatures ◽  
Chromosome Abnormality ◽  
Mutant Gene ◽  
Cenchrus Ciliaris ◽  
High Incidence ◽  
Low Humidity ◽  
Recessive Mutant ◽  
Chromosome Disjunction

Synaptic mutants are present in  Cenchrus ciliaris L This species, due to the presence of linear bivalents and occasion­al trivalents and quadrivalents, is an intermediate desynaptic species. In addition, geographical distribution and environmental factors, such as high temperatures and low humidity, could also have had an influence on the desynapsis observed.The disjunction of chromosomes during anaphase I was mostly abnormal in this desynaptic species. Precocious disjunction of chromosomes into chromatids occurred during anaphase I Due to the high incidence of this chromosome abnormality, a mutant gene,  'pc'  responsible for the disjunction of chromosomes, must be present. The absence of cytokinesis in one specimen indicates a recessive mutant gene,  'va' to be active in this species.

scholarly journals High Temperatures Decrease the Flight Capacity of Diaphorina citri Kuwayama (Hemiptera: Liviidae)

Insects ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 394
Author(s):  
Carlos A. Antolinez ◽  
Tobias Moyneur ◽  
Xavier Martini ◽  
Monique J. Rivera
Keyword(s):  
Relative Humidity ◽  
High Temperatures ◽  
Insect Pest ◽  
The United States ◽  
Diaphorina Citri ◽  
Long Distance ◽  
Flight Duration ◽  
Custom Made ◽  
Flight Capacity ◽  
Low Humidity

Diaphorina citri Kuwayama (Hemiptera: Liviidae), commonly known as Asian citrus psyllid (ACP), is an invasive insect pest and the vector of the bacterium causing Huanglongbing (HLB), a lethal disease of citrus. In the United States, ACP has been established in all citrus-producing zones, all of which have different environmental conditions. The spread of ACP and, more importantly, HLB, has progressed differently depending on the state, with more rapid spread in Florida and Texas than in California. Climatic variations between the regions are likely a strong factor in the difference in the rate of spread. Despite this, it is unknown how the flight capacity of D. citri is influenced by high temperatures (>30 °C) and subsequently, low humidity experienced in California but not in Texas or Florida. In this study, by using a custom-made, temperature-controlled flight mill arena, we assessed the effect of high temperatures on the flight capacity and flight propensity of D. citri under low (20–40%) and high (76–90%) relative humidity conditions. We found that temperature and humidity influence the propensity to engage in short or long-distance flight events. Psyllids exposed to temperatures above 43 °C only performed short flights (˂60 s), and a high relative humidity significantly decrease the proportion of long flights (≥60 s) at 26 and 40 °C. The flight capacity for insects who engaged in short and long flights was significantly affected by temperature but not by humidity. For long flyers, temperature (in the 26–43 °C range) was negatively correlated with distance flown and flight duration. The most favorable temperature for long dispersion was 26 °C, with suboptimal temperatures in the range of 32–37 °C and the least favorable temperatures at 40 and 43 °C. In conclusion, D. citri is able to fly in a broad range of temperatures and efficiently fly in high and low humidity. However, temperatures above 40 °C, similar to those experienced in semi-arid environments like Southern California or Arizona, are detrimental for its flight capacity.

scholarly journals Large Carpenter Bees as Agricultural Pollinators

2010 ◽  
Vol 2010 ◽  
pp. 1-7 ◽  
Author(s):  
Tamar Keasar
Keyword(s):  
Geographical Distribution ◽  
High Temperatures ◽  
Mass Rearing ◽  
Food Plants ◽  
Nectar Robbing ◽  
Pollination Service ◽  
Carpenter Bees ◽  
Wide Range ◽  
Low Illumination ◽  
Greenhouse Tomatoes

Large carpenter bees (genusXylocopa) are wood-nesting generalist pollinators of broad geographical distribution that exhibit varying levels of sociality. Their foraging is characterized by a wide range of food plants, long season of activity, tolerance of high temperatures, and activity under low illumination levels. These traits make them attractive candidates for agricultural pollination in hot climates, particularly in greenhouses, and of night-blooming crops. Carpenter bees have demonstrated efficient pollination service in passionflower, blueberries, greenhouse tomatoes and greenhouse melons. Current challenges to the commercialization of these attempts lie in the difficulties of mass-rearingXylocopa, and in the high levels of nectar robbing exhibited by the bees.

scholarly journals Geographical distribution of sheep breeds in Brazil and their relationship with climatic and environmental factors as risk classification for conservation

2014 ◽  
Vol 1 (1) ◽  
pp. 3 ◽  
Author(s):  
Concepta McManus ◽  
Potira Hermuche ◽  
Samuel Paiva ◽  
José Ferrugem Moraes ◽  
Cristiano de Melo ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Geographical Distribution ◽  
Risk Classification ◽  
Sheep Breeds

scholarly journals Prospects for The Use of Thermotolerant Microorganisms for Remediation of Oil-Contaminated Soils

2020 ◽  
Author(s):  
S.A. Aitkeldiyeva ◽  
E.R. Faizulina ◽  
L.G. Tatarkina ◽  
A.V. Alimbetova ◽  
O.N. Auezova ◽  
...  
Keyword(s):  
High Temperatures ◽  
Contaminated Soils ◽  
Soil Cover ◽  
Molecular Genetic ◽  
Taxonomic Diversity ◽  
Oil Fields ◽  
Vital Activity ◽  
Genetic Characteristics ◽  
Low Humidity ◽  
Oil And Oil Products

Most of the world's oil fields are concentrated in geographic areas with high temperature conditions. One of the main problems of remediation of territories in hot climates is the fact that high temperatures reduce the viscosity of oil and, thus, accelerate its diffusion into the soil. This greatly complicates the processes of soil cover restoration using conventional methods. An alternative can be bioremediation using the oil-oxidizing microorganisms that are resistant to high temperatures and low humidity. The presented review is devoted to the analysis of studies of thermotolerant microorganisms by scientists from different countries with the aim of using them in the remediation of contaminated soils from oil and oil products. The data on the influence of the main environmental factors, such as temperature, oxygen, pH, salinity, aeration, the presence of nutrients, etc., on the viability and vital activity of thermotolerant hydrocarbon-oxidizing microorganisms are presented. Examples of biochemical and molecular genetic characteristics of thermotolerant microorganisms are given. Their taxonomic diversity is shown, and examples of the degradation of individual oil components by active strains are given.

scholarly journals Trisomy 13: a new recurring chromosome abnormality in acute leukemia

Blood ◽  
1990 ◽  
Vol 76 (8) ◽  
pp. 1614-1621 ◽  
Author(s):  
H Dohner ◽  
DC Arthur ◽  
ED Ball ◽  
RE Sobol ◽  
FR Davey ◽  
...  
Keyword(s):  
Acute Leukemia ◽  
Myeloid Leukemia ◽  
De Novo ◽  
Chromosome Abnormality ◽  
Cell Receptor ◽  
Trisomy 13 ◽  
Lymphoid Leukemia ◽  
High Incidence ◽  
T Cell Receptor Beta ◽  
Hematopoietic Precursor

Abstract A new recurring chromosome abnormality was identified in 8 of 621 consecutive successfully karyotyped adults with de novo acute leukemia. These eight patients had trisomy 13 as the sole cytogenetic abnormality. On central morphologic review, five cases were classified as subtypes of acute myeloid leukemia, one as acute mixed lymphoid and myeloid leukemia, one as acute lymphoid leukemia, and one as acute undifferentiated leukemia. Blasts of all eight cases expressed one or more myeloid differentiation antigens. Three also expressed T-lineage- associated antigens; however, none of these had rearrangement of the T- cell receptor beta, gamma, or delta genes. Four of six cases tested were TdT positive. All eight patients with trisomy 13 were treated with intensive induction chemotherapy; only three entered a short-lived complete remission. Survival of patients with trisomy 13 ranged from 0.5 to 14.7 months, and was significantly shorter than that of the remaining patients (median 9.5 v 16.2 months, P = .007). We conclude that trisomy 13 is a rare, recurring clonal chromosome abnormality in acute leukemia associated with a poor prognosis. Malignant transformation of an immature hematopoietic precursor cell is suggested by the expression of antigens characteristic of both the myeloid and lymphoid lineage, the high incidence of TdT positivity, and the morphologic heterogeneity in these leukemias.

scholarly journals High temperatures and absence of light affect the hatching of resting eggs of Daphnia in the tropics

2016 ◽  
Vol 88 (1) ◽  
pp. 179-186 ◽  
Author(s):  
Thécia A.S.V. Paes ◽  
Arnola C. Rietzler ◽  
Diego G.F. Pujoni ◽  
Paulina M. Maia-Barbosa
Keyword(s):  
Environmental Factors ◽  
High Temperatures ◽  
Aquatic Ecosystems ◽  
Resting Eggs ◽  
Negative Influence ◽  
Southeastern Brazil ◽  
Light Conditions ◽  
Tropical Environments ◽  
The Tropics ◽  
Hatching Rates

Temperature and light are acknowledged as important factors for hatching of resting eggs. The knowledge of how they affect hatching rates of this type of egg is important for the comprehension of the consequences of warming waters in recolonization of aquatic ecosystems dependent on dormant populations. This study aimed at comparing the influence of different temperature and light conditions on hatching rates of Daphnia ambigua andDaphnia laevis resting eggs from tropical environments. The ephippia were collected in the sediment of three aquatic ecosystems, in southeastern Brazil. For each lake, the resting eggs were exposed to temperatures of 20, 24, 28 and 32 °C, under light (12 h photoperiod) and dark conditions. The results showed that the absence of light and high temperatures have a negative influence on the hatching rates. Statistical differences for hatching rates were also found when comparing the studied ecosystems (ranging from 0.6 to 31%), indicating the importance of local environmental factors for diapause and maintenance of active populations.

scholarly journals Evidence from chimaeras for the pattern of proliferation of epidermis in the mouse

1977 ◽  
Vol 29 (3) ◽  
pp. 279-284 ◽  
Author(s):  
Margaret C. Green ◽  
Dianne Durham ◽  
Thomas C. Mayer ◽  
Peter C. Hoppe
Keyword(s):  
Cell Proliferation ◽  
Clonal Growth ◽  
Mutant Gene ◽  
Agouti Locus ◽  
Recessive Mutant

SUMMARYThe recessive mutant gene downless (dl) causes abnormal texture of the coat and absence of hair on the tail. The dl locus had previously been shown to act in the epidermis and not in the dermis. To obtain evidence on the pattern of proliferation of epidermis, downless ↔ normal chimaeras were produced by embryo aggregation, and the pattern of normal and mutant hair in the coat was examined. The chimaeras showed a pattern of narrow transverse stripes of normal and abnormal hair. This pattern was similar to that found in mice chimaeric for alleles at the agouti locus known to act in the dermis. This evidence supports the conclusion that the pattern of cell proliferation is similar in dermis and epidermis, and is compatible with the hypothesis that both tissues proliferate by lateral coherent clonal growth from a randomly mixed array of longitudinally arranged cells.

Sign in / Sign up

Export Citation Format

Share Document