Boško Milovanović

Recent changes in Serbian climate extreme indices from 1961 to 2010

The evolution of daily extreme temperature and precipitation from 1961 to 2010 in Serbia was investigated. Trends of five temperature indices, three precipitation indices, and four combined indices were calculated at ten temperature and ten precipitation stations located within the study area, and their corresponding significances were tested using the Student’s t test. Obtained results suggest that the time periods of extremely hot weather last longer, while the periods of extremely cold weather are shortened. Trends of duration of extreme temperature conditions were most pronounced in summer season. Periods of mild weather conditions are extended. Amount and intensity of precipitation had statistically significant increase only during autumn and were most pronounced in the northern and western parts of the country. On an average, there was no significant decrease in the maximum number of consecutive dry days or increase in the wet days (except in autumn). The investigation of four combined temperature-precipitation regimes showed the domination of “dry” regimes over “wet,” increasing trend of “warm” regimes and decreasing trend of “cold” regimes. The correlation between the examined extreme indices and the large-scale circulation patterns showed that EA and NAO had significant influence on duration of winter warm periods, while their influence on duration of cold periods cannot be confirmed with certainty.

Strain-specific helper T cell profile in the gut-associated lymphoid tissue

C57BL/6, BALB/c and NOD mice are among the most frequently used strains in autoimmunity research. NOD mice spontaneously develop type 1 diabetes (T1D) and they are prone to induction of experimental autoimmune encephalomyelitis (EAE). Both diseases can be routinely induced in C57BL/6 mice, but not in BALB/c mice. Also, C57BL/6 mice are generally considered T helper (Th)1-biased and BALB/c Th2-biased mice. Having in mind increasingly appreciated role of gut associated lymphoid tissue (GALT) cells in autoimmunity, especially in relation to gut Th17 and regulatory T (Treg) cells, our aim was to determine if there are differences in proportion of CD4+ T cell populations in mesenteric lymph nodes and Peyers patches of these mouse strains. Lower proportion of Treg was observed in NOD PP, Th2 cells dominated in BALB/c mice in mesenteric lymph nodes (MLN) and Peyers patches (PP), while Th1 cells prevailed in C57BL/6 MLN. Intradermal immunization of mice with complete Freunds adjuvant resulted in significant difference in Th cell distribution in GALT of NOD mice. Differences were less pronounced in C57BL/6 mice, while GALT of BALB/c mice was almost unresponsive to the immunization. The observed strain- and tissue-dependent changes in Treg proportion after the immunization was probably a consequence of different CCR2 or CCR6-related migration patterns and/or in situ Treg proliferation. In conclusion, NOD, a highly autoimmunity-prone mouse strain, exhibits more profound GALT-related immune response upon immunization compared to the strains that are less prone to autoimmunity.

Low ionospheric reactions on tropical depressions prior hurricanes

Abstract We study the reactions of the low ionosphere during tropical depressions (TDs) which have been detected before the hurricane appearances in the Atlantic Ocean. We explore 41 TD events using very low frequency (VLF) radio signals emitted by NAA transmitter located in the USA and recorded by VLF receiver located in Belgrade (Serbia). We found VLF signal deviations (caused ionospheric turbulence) in the case of 36 out of 41 TD events (88%). Additionally, we explore 27 TDs which have not been developed in hurricanes and found similar low ionospheric reactions. However, in the sample of 41 TDs which are followed by hurricanes the typical low ionosphere perturbations seem to be more frequent than other TDs.

CLIMATE REGIONALIZATION OF SERBIA ACCORDING TO KÖPPEN CLIMATE CLASSIFICATION

The paper presents a concise overview of the theoretical framework on which climate classifications are based. Beside short review of climate classifications, namely climatic regionalization for Serbia (or wider area including Serbia), main deficiency of these research was ascertained (which primarily relate to the period on the basis of which climate regionalization was carried out). The criteria of the Koppen climate classification are presented, on the basis of which the climate regionalization of Serbia has been carried out. The methodology of making maps of air temperatures and precipitation amounts has been described, on the basis of which a map of the climate regions of Serbia has been created. Spatial distribution of the types and subtypes of the climates in Serbia has been briefly described. It has been pointed to the constraints of the climate regionalization that arise from the theoretical bases of the climate classifications, but also from nature of the collected data and the applied methodology.

Tropical temperature altitude amplification in the hiatus period (1998-2012)

In the period 1998-2012 there was a stagnation in temperature rise, despite the GHGs radiation forcing is increased (hiatus period). According to Global Circulation Models simulations, expected response on the rise of GHGs forcing is tropical temperature altitude amplification - temperature increases faster in higher troposphere than in lower troposphere. In this paper, two satellite data sets, UAH MSU and RSS, were used to test altitude temperature amplification in tropic (20°N-20°S) in the hiatus period. We compared data from satellite data sets from lower troposphere (TLT) and middle troposphere (TMT) in general and particularly for land and ocean (for UAH MSU). The results from both satellite measurements showed the presence of hiatus, i.e. slowdown of the temperature rise in the period 1998-2012 compared to period 1979-2012 (UAH MSU) and temperature fall for RSS data. Smaller increase, i.e. temperature fall over ocean showed that hiatus is an ocean phenomenon above all. Data for UAH MSU showed that temperature altitude amplification in tropic was not present either for period 1979-2012, or 1998-2012. RSS data set also do not show temperature altitude amplification either for longer (1979-2012), or for shorter period (1998-2012). RSS data for successive 15-year periods from 1979-1993 till 1998-2012 does not show tropical temperature altitude amplification and in one case negative trend is registered in TLT and in two cases in TMT. In general, our results do not show presence of temperature altitude amplification in tropic in the hiatus period. [Projekat Ministarstva nauke Republike Srbije, br. III47007]

The Frequency of Allele CCR5∆32 in a Serbian Population / UČESTALOST ALELA CCR5∆32 U SRPSKOJ POPULACIJI

Summary Background: The mutant CCR5Δ32 allele confers resist- ance to HIV infection. Several hypotheses regarding its ori- gin and persistence in the human population have been proposed. It is assumed that the Δ32 mutation was intro- duced in Northern or Eastern Europe and that it spread to the south. Although the frequency of CCR5Δ32 was deter- mined in numerous European nations and regions, further data are needed to complete the puzzle of CCR5Δ32 dis- tribution within the continent. Methods: To this end, CCR5Δ32 frequency was determined in a Serbian population (sample size 352). DNA was extracted from peripheral whole blood and polymerase chain reaction specific for CCR5 gene was performed. A reaction product of 263 bp was obtained from the wild- -type CCR5 sequence and a product of 231 bp was ob- tained from the truncated CCR5Δ32 sequence. Results: Overall allele frequency of CCR5Δ32 is 4.55%; 0.57% of individuals in the examined population are homo- zygous and 8.52% are heterozygous for CCR5Δ32. Conclusions: The determined frequency of the CCR5Δ32 allele in a Serbian population is unexpectedly low, consid- ering ethnically related populations. Keywords: CCR5, Δ32, Serbia. Kratak sadržaj Uvod: Nosioci alela CCR5Δ32 su relativno rezistentní na infekciju HIV-om. Postoji nekoliko hipoteza o poreklu i održanju ovog alela u ljudskoj populaciji. Pretpostavlja se da je mutacija A32 nastala u populaciji severne ili istočne Evrope i da se potom proširila ka jugu. lako je učestalost CCR5Δ32 odredena u mnogim evropskim populacijama, dodatni podaci su neophodni za formiranje sveobuhvatne slike o distribuciji CCR5Δ32 u Evropi. Zbog toga smo u našoj študiji odredili učestalost CCR5Δ32 u srpskoj popu- laciji, za koju do ovog rada nisu postojali takvi podaci. Metode: DNK je izolovana iz periferne krvi 352 osobe. U reakciji lančanog umnožavanja koriščeni su prajmeri spe- cifični za gen CCR5. Dobijen je proizvod od 263 bp na osnovu matrice »wild type«, sekvence CCR5 gena, a proiz- vod od 231 bp na osnovu okrnjene sekvence gena CCR5 (CCR5A32). Ukupna učestalost alela CCR5Δ32 u srpskoj populaciji iznosi 4,55%. Rezultati: Od ukupnog broja analiziranih osoba, identifiko- vano je 8,52% heterozigotnih i 0,57% homozigotnih nosila- ca za ovaj alel. Zaključak: Utvrdená učestalost alela CCR5Δ32 u srpskoj populaciji je neočekivano niska, u poredenju sa učestalošču u ostalim slovenskim populacijama.