scholarly journals Tubulin recycling limits cold tolerance

2019 ◽  
Author(s):  
Gabriella Li ◽  
Jeffrey K. Moore

AbstractAlthough cold temperatures have long been used to depolymerize microtubules, how temperature specifically affects the polymerization and depolymerization activities of tubulin proteins and how these lead to changes in microtubule networks in cells has not been established. We investigated these questions in budding yeast, an organism found in diverse environments and therefore predicted to exhibit dynamic microtubules across a broad range of temperatures. We measured the dynamics of GFP-labeled microtubules in living cells and found that lowering the temperature from 37°C to 10°C decreased the rates of both polymerization and depolymerization, decreased the amount of polymer assembled before catastrophes and decreased the frequency of microtubule emergence from nucleation sites. Lowering to 4°C caused rapid loss of almost all microtubule polymer. We provide evidence that these effects on microtubule dynamics may be explained in part by changes in the co-factor-dependent conformational dynamics of tubulin proteins. Ablation of tubulin-binding co-factors further sensitizes cells and their microtubules to low temperatures, and we highlight a specific role for TBCB/Alf1 in microtubule maintenance at low temperatures. Finally, we show that inhibiting the maturation cycle of tubulin by using a point mutant in β-tubulin confers hyper-stable microtubules at low temperatures, rescues the requirement for TBCB/Alf1, and improves the cold tolerance of the yeast. Together, these results reveal an unappreciated step in the tubulin cycle in cells and suggest that this step may be a key limiting factor in the thermal tolerance of organisms.

2019 ◽  
Vol 46 (1) ◽  
pp. 30 ◽  
Author(s):  
Peilu Zhou ◽  
Qiyao Li ◽  
Guangliang Liu ◽  
Na Xu ◽  
Yinju Yang ◽  
...  

Chilling stress increases the amount of polyphenols, especially lignin, which protects tobacco (Nicotiana tabacum L. cv. k326) from chilling stress. To clarify the molecular biosynthesis mechanism of the key representative compounds, specifically lignin, RNA sequencing and ultra-high pressure liquid chromatography coupled to quadrupole-time of flight mass spectrometry technologies were used to construct transcriptomic and metabolomic libraries from the leaves of tobacco plants subjected to normal (25°C) and chilling (4°C) temperature treatments. Transcriptomic libraries from the different samples were sequenced, generating more than 40million raw reads. Among nine samples, metabolomic analysis identified a total of 97 encoding enzymes that function in the key steps of pathways related to polyphenol biosynthesis, where 42 metabolites were also located. An integrated analysis of metabolic and transcriptomic data revealed that most of the intermediate metabolites and enzymes related to lignin biosynthesis were synthesised in the leaves under chilling stress, which suggests that the biosynthesis of lignin plays an important role in the response of tobacco leaves to cold temperatures. In addition, the cold insensitivity of chalcone synthase genes might be considered to be an important rate-limiting factor in the process of precursor substance flow to flavonoid biosynthesis under chilling stress. Furthermore, the upregulated expression of phenylalanine ammonia lyase (PAL), hydroxycinnamoyl transferase (HCT) and cinnamyl-alcohol dehydrogenase (CAD) under chilling stress is the key to an increase in lignin synthesis. This study provides a hypothetical basis for the screening of new active metabolites and the metabolic engineering of polyphenols in tobacco.


2006 ◽  
Vol 63 (3) ◽  
pp. 255-261 ◽  
Author(s):  
Renata Pereira da Cruz ◽  
Sandra Cristina Kothe Milach ◽  
Luiz Carlos Federizzi

Cold tolerance of rice (Oryza sativa L.) during the reproductive stage is important to guarantee high yield under low temperature environments. Field selection, however, does not allow identification of adequate tolerance sources and limits selection of segregating lines due to variable temperature. The objective of this study was to devise methods for distinguishing rice genotypes as to their cold tolerance at the reproductive stage when evaluated under controlled temperature. The effect of cold temperatures was investigated in six rice genotypes at 17°C for varying length of time (three, five, seven and ten days) at two reproductive stages (microsporogenesis and anthesis). Cold tolerance was measured as the percentage of reduction in panicle exsertion and in spikelet fertility. Evaluating cold tolerance through the reduction in panicle exsertion did not allow for the distinction between cold tolerant from cold sensitive genotypes and, when the reduction in spikelet fertility was considered, a minimum of seven days was required to differentiate the genotypes for cold tolerance. Genotypes were more sensitive to cold at anthesis than at microsporogenesis and, as these stages were highly correlated, cold screening could be performed at anthesis only, since it is easier to determine. Rice cold tolerance at the reproductive stage may be characterized by the reduction in spikelet fertility due to cold temperature (17°C) applied for seven days at anthesis.


2021 ◽  
pp. 3-8
Author(s):  
Ю.А. Шнейдер ◽  
Е.В. Каримова ◽  
Ю.Н. Приходько ◽  
Е.Н. Лозовая ◽  
Т.С. Живаева

Томат – важнейшая овощная культура с ежегодным увеличением объемов его производства во всем мире. В Российской Федерации последние несколько лет активно развиваются предприятия защищенного грунта, специализирующиеся на производстве томатов. Вместе с тем растения томата поражают более 200 различных вредителей и болезней. Возбудители вирусных болезней растений – важный ограничивающий фактор для многих отраслей растениеводства, в том числе овощеводства. В последние годы в европейских странах производство томатов в открытом и защищенном грунте пострадало от серьезных потерь, вызванных, главным образом, вирусными фитопатогенами. В статье представлен обзор трех наиболее опасных вирусов, возбудителей болезней томатов – коричневой морщинистости плодов томата, мозаики пепино, пятнистого увядания томата. Эти вирусы неоднократно были выявлены в целом ряде стран практически на всех континентах и вызвали значительные экономические потери в странах своего распространения. Ввиду очень быстрого распространения и обнаружения опасных вирусов томата в ряде стран, занимающихся производством и дальнейшим экспортом семян и плодов томатов, Федеральная служба по ветеринарному и фитосанитарному надзору Российской Федерации (Россельхознадзор) с 27 июля 2020 года ввела в качестве временной карантинной фитосанитарной меры требование об отсутствии этих вирусов в семенах, посадочном материале и плодах растений-хозяев при их ввозе и перемещении по территории Российской Федерации. Результаты анализов фитосанитарного риска, проведенных в ФГБУ «ВНИИКР» в 2020 году, показали, что вирусы коричневой морщинистости плодов томата, мозаики пепино и пятнистого увядания томата соответствуют критериям карантинных для Российской Федерации организмов, вирусы способны проникнуть на территорию страны с подкарантинной продукцией, распространиться и нанести существенный ущерб развитию сельского хозяйства и экономической деятельности страны. Tomato is the most important vegetable crop with an annual increase in its production worldwide. In the Russian Federation, greenhouse industry specializing in the production of tomatoes have been actively developing over the past few years. At the same time, tomato plants affect more than 200 different pests and diseases. Pathogens of viral diseases of plants are an important limiting factor for many branches of crop production, including vegetable growing. In recent years, in European countries, the production of tomatoes in open field and greenhouses has suffered from serious losses caused mainly by viral phytopathogens. The article presents an overview of the three most dangerous viruses, pathogens of tomato diseases – tomato brown rugose fruit virus (ToBRFV), pepino mosaic virus (PepMV) and tomato spotted wilt virus (TSWV). These viruses have been repeatedly detected in a number of countries on almost all continents and have caused significant economic losses in the countries of their distribution. In view of the very rapid spread and detection of dangerous tomato viruses in a number of countries engaged in the production and further export of tomato seeds and fruits, Rosselkhoznadzor, from July 27, 2020, introduced as a temporary quarantine phytosanitary measure the requirement that these viruses are not present in seeds, planting material and fruits of host plants when they are imported and moved through the territory of the Russian Federation. The results of the phytosanitary risk analyses conducted at the Federal State Budgetary Institution «VNIIKR» in 2020 showed that ToBRFV, PepMV and TSWV meet the criteria of quarantine organisms for the Russian Federation, viruses are able to enter the territory of the country with quarantined products, spread and cause significant damage to the development of agriculture and economic activity of the country.


1962 ◽  
Vol 203 (5) ◽  
pp. 834-838
Author(s):  
Sidney S. Schreiber ◽  
Murray Oratz ◽  
Marcus A. Rothschild

Potassium exchange was studied in the intact working hypothermic guinea pig heart in vitro with K42. As at 37 C, buildup and washout experiments demonstrated two compartments of K exchange, but these behaved differently with reductions in temperature to 20 C. The rate of K exchange of the "fast" compartment decreased with lowered temperatures, whereas the rate of "slow" compartment exchange either remained unaffected or increased slightly. Ouabain had no apparent effect on the fast compartment K exchange. Toxic levels of ouabain, which inhibited entrance of K into the slowly exchanging phase at 37 C, showed a minimal effect on this compartment at 20 C. The decreased ouabain inhibition at 20 C was paralleled by a concomitant decrease in toxicity (contracture and ventricular fibrillation). It was postulated that intracellular cardiac K exchange involved two separate processes which responded differently to low temperatures. Ouabain action was indicated to be specifically on that process which was insensitive to cold temperatures.


Insects ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 767
Author(s):  
Xin Lü ◽  
Shi-chou Han ◽  
Zhi-gang Li ◽  
Li-ying Li ◽  
Jun Li

Trichogramma spp. is an important egg parasitoid wasp for biocontrol of agriculture and forestry insect pests. Trehalose serves as an energy source or stress protectant for insects. To study the potential role of trehalose in cold resistance on an egg parasitoid, cDNA for trehalose-6-phosphate synthase (TPS) and soluble trehalase (TRE) from Trichogramma dendrolimi were cloned and characterized. Gene expressions and enzyme activities of TdTPS and TdTRE were determined in larvae, prepupae, pupae, and adults at sustained low temperatures, 13 °C and 16 °C. TdTPS and TdTRE expressions had similar patterns with higher levels in prepupae at 13 °C and 16 °C. TdTPS enzyme activities increased with a decrease of temperature, and TdTRE activity in prepupae decreased sharply at these two low temperatures. In vitro reared T. dendrolimi could complete entire development above 13 °C, and the development period was prolonged without cold injury. Results indicated trehalose might regulate growth and the metabolic process of cold tolerance. Moreover, 13 °C is the cold tolerance threshold temperature and the prepupal stage is a critical developmental period for in vitro reared T. dendrolimi. These findings identify a low cost, prolonged development rearing method, and the cold tolerance for T. dendrolimi, which will facilitate improved mass rearing methods for biocontrol.


Parasitology ◽  
1999 ◽  
Vol 119 (S1) ◽  
pp. S7-S17 ◽  
Author(s):  
D. A. Wharton

SUMMARYLow temperatures affect the rate of growth, development and metabolism of parasites and when temperatures fall below 0°C may expose the parasite to the potentially lethal risk of freezing. Some parasites have mechanisms, such as diapause, which synchronise their life cycle with favourable seasons and the availability of hosts. Parasites of endothermic hosts are protected from low temperatures by the thermoregulatory abilities of their host. Free-living and off-host stages, however, may be exposed to subzero temperatures and both freezing-tolerant and freeze-avoiding strategies of cold hardiness are found. Parasites of ectothermic hosts may be exposed to subzero temperatures within their hosts. They can rely on the cold tolerance adaptations of their host or they may develop their own mechanisms. Exposure to low temperatures may occur within the carcass of the host and this may be of epidemiological significance if the parasite can be transmitted via the consumption of the carcass.


1983 ◽  
Vol 31 (7) ◽  
pp. 975-976 ◽  
Author(s):  
P Chieco ◽  
P J Boor

We performed glutathione (GSH) staining at a low temperature to prevent GSH release from the section and, hence, improve morphology. Fresh frozen sections of liver, lung, kidney, heart, and stomach were incubated for GSH activity in an ice bath (2-5 degrees C) for 5-10 min. Low temperature incubation prevented GSH diffusion out of cells and minimized migration of granules into vessels and outside of tissue. Incubation at low temperature generally reduced the intensity of the stain compared to the standard method. We conclude that low temperature incubation improves GSH localization in cells, probably by regulating the rate, formation, and the size of GSH-mercury orange complexes.


1992 ◽  
Vol 280 ◽  
Author(s):  
A. Estes Wickenden ◽  
D. K. Wickenden ◽  
T. J. Kistenmacher ◽  
S. A. Ecelberger ◽  
T. O. Poehler

ABSTRACTNucleation layers of GaN have been deposited in an MOCVD reactor on (0001) sapphire, over a range of temperatures and layer thicknesses, using either N2 or H2 carrier gas. The layers have been found to be continuous, textured films as deposited at low temperatures (600°C), but to reorder upon annealing, segregating into nucleation sites which exhibit the normal heteroepitaxial relationship with the sapphire substrate.


1967 ◽  
Vol 125 (1) ◽  
pp. 61-70 ◽  
Author(s):  
William J. Klein ◽  
Sam M. Beiser ◽  
Bernard F. Erlanger

Fluoresceinated antinucleoside globulins were shown to react with the nuclei of L cells. The pattern of nuclear fluorescence was similar to the distribution of nuclear DNA. This reaction was shown to be specific by the following control experiments: 1. Absorption of the specific antibody from an antiadenosine globulin eliminated all fluorescence. 2. Treatment of the cells with nonfluorescent antiadenosine globulin, followed by staining with the fluorescent antiadenosine eliminated almost all of the fluorescence of the nucleus. 3. Treatment of the cells with DNase destroyed the ability of the nucleus to react with antiuridine fluorescent antibodies. 4. Fluoresceinated anti-BSA did not produce nuclear fluorescence. Nuclear fluorescence occurred only in cells harvested during the period of maximum DNA synthesis as measured by the uptake of thymidine. This correlates with the previously demonstrated specificity of the antibodies for denatured DNA.


2017 ◽  
Vol 19 (17) ◽  
pp. 10738-10747 ◽  
Author(s):  
Steffen Büning ◽  
Abhishek Sharma ◽  
Shivang Vachharajani ◽  
Estella Newcombe ◽  
Angelique Ormsby ◽  
...  

In-cell temperature jump experiments induce monomer collapse, misfolding and self-association of the Huntingtin exon 1 protein.


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