[Tree-rings width variability along latitudinal and paleolatitudinal gradients].

Processed are 57596 dated series of tree-rings width (TRW ) from the International Tree-ring Data Bank. The results obtained indicate that: 1. The TRW is strongly correlated with tree age. Periods of cambium activity are strictly dependent on the age of the trees. Therefore, there is a strong correlation between TRW and periods of radial growth. It is suggested that synchronization of the periods of radial growth in the first 150 years of trees life with cycles of climatic factors leads to increase in TRW . 2. Satisfactory coincidence between latitudinal profiles of TRW , on the one hand, and climatic and biological indicators, on the other hand, is observed. Latitudinal profile of TRW gets its form under the influence of climate and assimilating mass productivity. 3. Latitudinal change of the TRW in the Cretaceous had a pronounced displacement of a maximum from equator toward 30 °NL. Growth gain of Cretaceous gymnosperms was about twice higher than that of modern trees. Such asymmetry of paleolatitudinal profile of TRW sharply distinguishes it from modern latitudinal profiles that follow climatic parameters.

[AGGLUTINATION OF MESOPHYLL PLASTIDS AND OBLITERATION OF PHLOEM SIEVE TUBES ARE THE TOTAL RESULT OF SEASONAL PAUSES IN PHOTOSYNTHATE EXPORT].

Chloroplast agglutination and sieve tube obliteration are related to the different plant tissues: the agglutination--to the leaf mesophyll, and the obliteration--to the axis phloem. Being equally produced by photosynthate export dynamics, both phenomena are synchronous and can be used for diagnostics of seasonal flashes and pauses of photosynthetic activity with equal success. The nature of the mobility of chloroplast and their shuttle displacements from the nuclear envelope to the cell periphery connected with export dynamics have been established. It is assumed that nuclear envelope is the base structure of the endoplasmic reticulum (ER) inside which the chloroplasts are localized. Activation of photosynthesis and sugar accumulation inside the ER induces its expansion followed by centrifugal diffusion of chloroplasts. Come back effect--ER collapse, its return to the source--can be induced by the blockade of photosynthesis. Centripetal collapse is accompanied by plastid concentration around the nuclear envelope. Displacements of ER and the chloroplasts dislocating inside it are reversible. It depends on seasonal fluctuations of photosynthesis and export intensities. Changes in the volume of sieve tubes, which are due to the same reason, are irreversible. Each seasonal wave of photosynthesis and sugar export forms new series of sieve tubes, replacing obliterated ones.