Vol 8, No 3 (2018)

A mosaic of barren grounds (bars) and areas covered by vegetation often forms in grassy or shrubby communities in conditions of scarcity of environmental resources (e.g., water). Such landscapes have been named “two-phase mosaics”; this term emphasizes the discreteness of vegetation cover units. Fairy rings (FRs) are an example of such structures. There are two sets of competing hypotheses on the reasons behind FR formation: insect activity and self-organization. One of the main arguments against the second set of hypotheses is their inability to explain the FR life cycle: their emergence, ripening, maturation, and disappearance (death). The article proposes a simple cellular-automaton model of the vegetation cover formation. The model imitates the scarcity of resources (water and ash constituents) and generates different variants of the two-phase mosaic. The results depend on two parameters: limitation of resource inflow and plant growth rate. Sixteen percent of combinations of these parameters result in the formation of structures similar to FRs. The model reproduces not only the vegetation distribution pattern observed in the nature but also individual FR life cycles that are consistent with field descriptions. Thus, the model removes the main objection to self-organization as the main mechanism of FR formation.

In the previous publication (Logofet et al., 2017), we reported on constructing a matrix model for a local population of Eritrichium caucasicum at high altitudes of north-western Caucasus. The model described the population structure according to the stages of ontogeny and field data for 6 years of observation. Calibrated from the data, the matrices, L(t), of stage-specific vital rates, which projected the population vector at time t (t = 2009, 2010, …, 2013) to the next year, were dependent on t and naturally different, reflecting indirectly the temporal differences in habitat conditions that occurred during the observations. Therefore, the model turned out to be non-autonomous. In addition to the range of variations in the adaptation measure λ₁(L), we also obtained certain “age traits from a stage-structured model,” such as the average stage duration and the life expectancy for each stage. Those traits were uniquely determined for each given matrix L by a known (from the English literature) VAMC (virtual absorbing Markov chain) technique, while their variations for different years t pointed out the need to solve a mathematical problem of finding the geometric mean (G) of five matrices L(t) with a fixed pattern. The problem has no exact solution, whereas the best approximate one (presented here) results in the estimate of life expectancy as 3.5 years and that of the mean age at first flowering as 12 years. Given the data of 6-year observations, the forecast of whether the local population increases/declines in the long term draws on the range of possible variations in the measure λ₁(G) under reproductive uncertainty, and this range localizes entirely to the right of 1, though very close to λ₁ = 1 meaning a stable population.

Colonial hydroids are used as a natural model of a number of fundamental biological processes, including the self-organization of systems, which is most clearly expressed in the operation of the distribution system. Functional integration of the colonial organism is performed by the moving of intracavitary fluid (hydroplasm) along a tubular body represented by sprouts and the stolons that connect them. Hydroplasm movement occurs due to independent pulsations of hydrants and tubular coenosarc and frequently looks chaotic. However, food particles in hydroplasmatic flows (HPFs) can pass through the stolon at distances commensurate with the colonial organism length for one HPF. The formation of such HPFs is paradoxical, since, as demonstrated by our studies, the pulsator volumes are much smaller than the volume of registered unidirectional HPFs. The article presents the results of the study of (a) HPF length; (b) transverse stolon pulsations in different stolon internodes (modules); (c) HPF rate along the stolon modules; and (d) volumes of the main pulsators (hydrants, coenosarc regions). Microvideo recording for 1–2 h with a magnification of 100 and frequency of 4 frames/s is the basic method of study. The objects of study are seven linear Dynamena pumila colonies of six to eight sprouts each grown on glass from primary sprouts. The HPF length was determined visually by scanning the colony under a microscope for 1–2 h every minute for 10–20 s. Regular powerful HPFs usually started from the primary sprout. According to visual recording, their length was from two to seven stolon modules (6–20 mm). However, HPFs coming from the primary sprout could fill no more than two stolon modules (according to its volume). Consequently, the resulting total continuous HPF is composed of several local HPFs. By means of calculations, it was demonstrated that “swept volumes” (the difference between the max and min volumes) of certain pulsators is much less than the local HPF volume. While the compression of one to two hydrants is enough to form the weakest local HPF, simultaneous compression of ten to twenty hydrants is required to create a powerful HPF. The obtained data can be explained based on the hypothesis on the hydraulic synchronization of independent pulsators and coordinated involvement in the creation of total HPFs of intermediate sprouts, which are entered by the flow on its path; this results in food movement along the colony over significant distances.

The spatial organization of the bill tip organ in waterfowl is studied in 327 specimens from 35 species from the Anseriform order, including geese, swans, seaducks, shelducks, dabbling, and diving ducks. Two types of tactile epithelial formations, sensillar and asensillar, are revealed on the tips of the upper and lower jaws. The number of the mandibular formations always exceeds that of the maxillary. The combinations of these indicators differ significantly among the majority of the studied species. The studied species can be divided into three types based on combinations of the number of upper and lower tactile formations according to different foraging techniques: grazing (geese, swans, sheldgeese), pursuit diving (sea ducks), and dabbling (pochards, shelducks, dabbling ducks). The formation density per square mm correlates with the asymmetry of the bill tip organ (r = 0.55; p < 0.01; n = 327). The correlation is the greatest in dabbling species. The probable function of the bill tip organ, in addition to location and analyse of food particles, lies in the fact that dabbling species can communicate with each other via motions in the course of food intake. This helps them to save time and to optimize their individual distances when feeding in darkness.

In one of every ten cases, the reason behind female infertility turns out to be an orphan disease called hypogonadotropic hypogonadism, the only symptom of which is a reduced level of gonadotropins and, as a consequence, amenorrhea in females. Most often, hypogonadotropic hypogonadism is caused by disorder in the secretion of gonadoliberin, a product of the GNRH1 gene. However, the disease is heterogeneous one, so it may originate from either genetic or nongenetic causes. To study the genetic component of the disease pathogenesis, we conducted molecular-genetic analysis of 11 candidate genes controlling the synthesis and secretion of gonadoliberin, as well as several candidate genes functioning as neurodevelopment and neuroendocrine regulators. The study included a group of patients afflicted by hypogonadotropic hypogonadism of an isolated form (n = 10) and a control group of healthy women (n = 20). All women were of reproductive age, with no detected mutations in candidate genes that could cause any pathological effect. The data on candidate genes expression in white blood cells are indicative of an increased expression of the GNRH1 gene in the sampled patients as compared to the control group (p < 0.05). Other genes demonstrate heterogeneous expression in both the patients group and the control group. Thus, increased GNRH1 expression in blood cells appears to be associated with the isolated form of hypogonadotropic hypogonadism and may be used in the future as a disease marker.