3. Oknina (1945-1968) created the concept of deep rest as a process of isolation of protoplasm.

In other tree species (aspen, hornbeam, paper birch and tulip tree) growth begins slowly and lasts 3-4 weeks, then intensifies and after 60 days of active growth reaches 90% of annual growth.

Even in different varieties of the same species, such as apple trees, growth lasts unequally long. In some varieties, the shoots reach their maximum size faster, in others – later, although their size will be approximately the same. Studies conducted at the Research Institute of Horticulture in the GDR in Pilnitz (Dresden) showed that the first varieties will be more productive. This is due to the fact that the larger leaf surface photosynthesisoccurs over a long period of time.

From this we can draw the following conclusion: in most tree species, growth begins in early spring, when the temperature reaches a certain value, but stops at different times and long before the onset of the temperature at which growth can not occur. Tree growth is also affected by age: young seedlings tend to grow longer than adult trees. Seedling growth also begins earlier than in adult trees (here, probably, the main role is played by the higher air temperature around the seedlings). Shoots on the stumps of felled trees grow faster and have twice the growth period than seedlings.

The speed and duration of growth are different 123helpme.me even in different branches of the same plant. The main shoot in most plants begins to grow earlier and grows longer than the side shoots, and the branches near the top of the tree often begin to grow earlier and grow longer than the lower ones. The dormancy period in the branches of the upper tiers of the crown of apple and pear trees is longer than in the lower ones. If you cut the branches from the first days of December to mid-April and keep them in water, the percentage of buds that bloomed in the branches of the lower tiers of the crown is greater and only in the branches cut in April, it is the same. The growth of tree trunks in diameter begins later and lasts longer than growth in height. The total duration of growth of the tree trunk in diameter is greater than the duration of growth of shoots.

PA Henkel and E. 3. Oknina (1945-1968) created the concept of deep rest as a process of protoplasm separation. According to their ideas, when preparing plants for winter, they first accumulate spare nutrients, stop growing and reduce the intensity of physiological processes. Metabolism changes in the direction of accumulation of fats and lipoids, with decreasing temperature below zero, plasmodesma are separated and the cytoplasm is separated from the shell. The place of cytoplasm in the most part of space in covers, obviously, is occupied by water and phosphatides.

PA Henkel and E. 3. Oknina (1964) distinguish three phases of rest:

organic rest associated with changes in protein and nucleic metabolism; deep rest, characterized by the separation of protoplasm and the separation of plasmodesm; forced rest, when the separation ends and the protoplasmic connection between the cells is partially restored.

However, not in all tissues of plants that freeze, protoplasm is isolated. Where this phenomenon is observed, its degree may be different. Plants fall into a state of dormancy not only in the autumn-winter period, but also in summer during drought and heavy salinization of the soil. At the same time similar isolation of protoplasm is observed.

Interruption of organic dormancy is of great practical importance and is used in the so-called distillation of plants, when flowers (roses, azaleas, lilacs, etc.) are grown in greenhouses in winter. Previously, warm (37-39 ° for 9-12 hours) baths were used for this purpose. Ethylene chlorohydrin – C1CH2 – CH2OH (6.7 cm3 / 100 l of air volume for 24 hours) is now most often used. Ethylene chlorohydrin is also used to remove dormant potato tubers (40 cm3 / l of water for 5-30 minutes), especially during the summer planting of potatoes (thiourea, gibberellins, salts of hydrochloric acid, ethyl bromide, dichloroethylene, tri-chloroethylene and alkali metal xanthates).

Vegis (1932) conducted experiments on the removal of Hydrocharis winter buds from dormancy with the help of warm baths of different temperatures and established an unusually high temperature coefficient. Similar coefficients were found in shoots of different tree species and in the early distillation of winter buds. plants. Such high coefficients are characteristic only for thermal denaturation of proteins and dissolution of fats. Based on this, the concluded that the cause of early distillation should be considered the dissolution of cell lipoids and it is warm baths contribute to the dissolution of the phosphatide layer covering the cytoplasm of the cell.

Christiansen and Timan (1950) found that indolylacetic acid accelerates the breakdown of fats and the absorption of organic acids. Inhibitors – iodoacetate, arsenite, Na-fluoride act quite the opposite: carbohydrates and their breakdown products are converted into fats or lipoids. Based on experiments, Vegis (1955) suggested that the rapid distillation of dormant kidneys due to treatment of their IOC occurs as a result of the accelerated action of IOC on the loosening of the surface of the lipoid layer of the cytoplasm due to oxidative decomposition of lipoids. Thus, normal permeability to water, oxygen and nutrients is restored.

12/26/2011

Biology: fat-soluble vitamins. Abstract

The abstract provides information on fat-soluble vitamins

Vitamin A (retinol). The most specific function of vitamin A is its participation in the processes of vision (photo-reception). The photosensitive pigment rhodopsin, which is located on the outer segment of the human retinal rods (which are responsible for twilight vision), contains an oxidative form of vitamin A-retinal. An early symptom of vitamin A deficiency is a weakening of dark adaptation.

The daily requirement of adult pantothenic acid is 5-10 mg.

The main sources of pantothenic acid are liver (6.8 mg per 100 g), yeast (4.2 mg per 100 g), egg yolks, rye bread (0.6 mg per 100 g), green vegetable plants (0.3- 0.8 mg per 100 g) …

Folate (vitamin Sun). In foods, folate is mainly in an inactive form. The transformation of the bound form into biologically active occurs in the process of digestion of food under the influence of enzymes of the small intestine (conjugates). Free form of folate (pteroylglutamic acid) released by conjugate gases of digestive juices is absorbed in the small intestine and used by the body. Derivatives of folate include folinic acid (citrovorum factor and leucovorin). Ascorbic acid is required to convert folate to citrovorum factor. Vitamin B stimulates the conversion of folate in the liver to the active form of leucovorin.

The basis of the biological action of folate is its participation in the construction of porphyrin and hemin blood, which is due to its antianemic effect.

Folate deficiency is the most common form of vitamin deficiency. It is mostly found among the elderly and patients with alcoholism, pregnant women and nursing mothers, as well as in some diseases of various etiologies. The biochemical functions of folate are very diverse and are associated with its participation in the processes of biosynthesis of nucleic acids, methylation reactions and amino acid metabolism.

The body’s need for pyridoxine directly depends on the level of protein intake. It increases during pregnancy and lactation, exposure to ionizing radiation, heart failure. The source of vitamin B6 are products of animal and plant origin (liver, yeast, cereals, legumes, fruits, vegetables).

Vitamin PP (niacin). The main physiological value of vitamin PP is determined by its role in redox processes as an electron carrier. It is part of two coenzymes (NAD and NADH) where hydrogenase.

Under natural conditions, vitamin PP occurs in two forms: nicotinic acid and nicotinamide. In the human body, vitamin PP is formed from the amino acid tryptophan (1 mg of 60 mg of tryptophan).

In the absence of vitamin PP there is a disease of pellagra (from the Italian. Pellagra – rough skin), which is characterized by inflammation of the skin, gastrointestinal tract, lesions of the central nervous system. Symptoms of this disease are inflammation of the skin (dermatitis; Fig. 10) of the face and other exposed areas of the body that are exposed to sunlight, skin sensitivity, irritability, lethargy, incoordination (ataxia), psychosis (in severe cases, possible dementia – dementia), as well as impaired secretion of gastric juice and persistent diarrhea (diarrhea), lack of papillae on the tongue.

Pellagra occurs with a monotonous diet of corn, which contains vitamin PP in a bound state, and a deficiency of the amino acid tryptophan, which is an important source of this vitamin. Chronic intestinal diseases can cause the development of endogenous PP-hypovitaminosis.

The main sources of vitamin PP are yeast, cereals, wholemeal bread, bran, legumes, offal, meat, fish, as well as some vegetables and dried mushrooms.

With a deficiency of vitamin Bg in the body there are deep disorders of protein metabolism, which are manifested in inflammation of the skin (dermatitis), muscle weakness, irritability, hair loss, loss of appetite, nausea and vomiting. Sometimes there are seizures (in children), anemia, decreased immunity, depression, neuritis. This disease resembles inflammation of the skin (dermatitis) in pellagra, but is not amenable to treatment with vitamin PP. Vitamin B6 deficiency is characterized by perineal injection.

Signs of hypovitaminosis B6 occur in patients taking drugs – pyridoxine antagonists, in alcoholics, as well as in women taking contraceptives. Causes of pyridoxine deficiency can be chronic diseases of the gastrointestinal tract, hereditary defects in the functioning of pyridoxine-dependent enzymes (homocystinuria, cystathionuria, hereditary xanthurenuria, pyridoxine-dependent anemia).

An adult’s need for vitamin B6 is 2.5 – C mg per day. Provision is determined by the content of 4-pyridoxy acid in the daily urine (norm 3-5 mg), pyridoxine in the blood (norm 100 μg / l) and serum (norm 70 μg / l). To detect vitamin B deficiency, it is also important to increase the content of xanthurenic acid in the urine after loading with tryptophan (more than 50 mg per day).