Low-molecular-weight ligands in plants: role in metal homeostasis and hyperaccumulation.

Mineral nutrition is one of the key factors determining plant productivity. In plants, metal homeostasis is achieved through the functioning of a complex system governing metal uptake, translocation, distribution, and sequestration, leading to the maintenance of a regulated delivery of micronutrients to metal-requiring processes as well as detoxification of excess or non-essential metals. Low-molecular-weight ligands, such as nicotianamine, histidine, phytochelatins, phytosiderophores, and organic acids, play an important role in metal transport and detoxification in plants. Nicotianamine and histidine are also involved in metal hyperaccumulation, which determines the ability of some plant species to accumulate a large amount of metals in their shoots. In this review we extensively summarize and discuss the current knowledge of the main pathways for the biosynthesis of these ligands, their involvement in metal uptake, radial and long-distance transport, as well as metal influx, isolation and sequestration in plant tissues and cell compartments. It is analyzed how diverse endogenous ligand levels in plants can determine their different tolerance to metal toxic effects. This review focuses on recent advances in understanding the physiological role of these compounds in metal homeostasis, which is an essential task of modern ionomics and plant physiology. It is of key importance in studying the influence of metal deficiency or excess on various physiological processes, which is a prerequisite to the improvement of micronutrient uptake efficiency and crop productivity and to the development of a variety of applications in phytoremediation, phytomining, biofortification, and nutritional crop safety.

[Comparative analysis of the monopodial and sympodial models of bulb branching in Galanthus L]. / Sravnitel'nyi analiz monopodial'noi i simpodial'noi modelei vozobnovleniia lukovitsy u Galanthus L..

We have examined sympodial and monopodial models of bulb branching in Galanthus. The issue of the position of the reduced prophyll is discussed. We proposed a method of formal interpretation: parts of the plant were positioned on diagrams; several variants of axial schemes were matched to each diagram; the schemes were divided into two classes, monopodial and sympodial ones, and stability of each class was estimated. In order to decide about the model of Galanthus bulb branching, we have examined plants with additional inflorescences and plants with additional leaf series. We have shown that the sympodial model predicts the presence of the reduced prophyll at the base of the innovation bud in all studied cases. Consecutive stages of prophyll reduction (prophyll of the innovation bud) can be followed in Amaryllidaceae in the following sequence: Zephyranthes, a well-developed large prophyll with green lamina; Vallota, a developed prophyll with reduced green lamina; Haemanthus, a thin chaffy short-living prophyll. At the end of this sequence is Galanthus with completely reduced prophyll at the innovation bud.

[Primary cancer of the duodenum]. / O pervichnom rake dvenadtsatiperstnoi kishki.

8 patients with primary carcinoma of the duodenum were operated upon: 3 pancreatoduodenal resections were carried out upon 3 patients. 1 patient underwent duodenectomy, the rest were mitigating and exploratory interventions. There were no fatal outcomes after radical interventions. The authors believe that radical operations for carcinoma of the duodenum allow to look forward to a longlasting cure.

[Importance of the method of timely external drainage of the pancreatic duct in transduodenal papillectomy and pancreatoduodenal resection]. / Znachenie metodiki vremennogo naruzhnogo drenirovaniia pankreaticheskogo protoka pri transduodenal'noi papillektomii i pankreatoduodenal'noi rezektsii

With the aim of prophylaxis against postoperative pancreatitis in transduodenal papillectomy and pancreatoduodenal resection the authors have elaborated the technic of a provisional external drainage of Wirsung's duct by means of a controlled transnasal drainage. Ten operations were performed using this technic. There were two deaths. The recommended technic provides a free outflow of the pancreatic juice from the pancreas outwardly during several days after the operation.

[Results of repeated operations in cancer of the major duodenal papilla]. / Rezul'taty povtornykh operatsii pri rake bol'shogo duodenal'nogo sosochka.

15 repeated operations for cancer of the major duodenal papilla were carried out. Gastroduodenal obstruction, recurrent jaundice, external bile fistulas, uneffective first operation served as indications for these interventions. Pathological conditions following a radical operation in cancer of the major duodenal papilla are not always due to the progress of the tumor. Repeated operations for cancer of this localization are by far justified with appropriate indications.