An Algorithm for Calculation of n-Dimensional Nonlinear Dependencies – Behaviour Tests on Rats

The evaluation of the data obtained during the behaviour tests always leads to the problem of multiple correlation, very often with non-linear dependencies on the target. All mathematical and statistical procedures that have been used so far are based on the assumption of an equation for the desired correlation for which parameters and related statistical equivalents are determined eventually. The MODAK system applied here (MODAK = algorithms of modelling for the calculation of multi-dimensional non-linear mathematical models) breaks down a complex correlation into individual dependencies in a mathematical and statistical way and selects suitable equations for each of them independently and determines the corresponding parameters. The numerical example evaluates data of behaviour tests on rats. First results obtained on the correlations of various behaviour tests indicate both the possibility of selecting suitable tests independent of each other and a better interpretation of the observed patterns of behaviour taking into account the interrelations between the tests. In addition, MODAK is a method which can be applied as a matter of course in a general way to all cases which call for the reduction and analysis of data occurring in process and system analysis and in the evaluation of test results requiring statistical modelling. So far, MODAK applications range from engineering sciences to medicine.     

Changing behavior of surface immunoglobulin on mouse B lymphocytes during immune development: I. LPS-induced changes in the lateral mobility of B lymphocyte surface immunoglobulins on two populations which express different surface immunoglobulin phenotypes

The redistribution of surface membrane immunoglobulin molecules (sIg) was studied in two functionally distinct populations of mouse splenic B lymphocytes, namely, those bearing membrane IgM(IgG^?) and those bearing IgG. Brief exposure to mitogenic doses of bacterial lipopolysaccharide (LPS) produced direct but differential effects on the subsequent ability of specific antibodies to induce this redistribution on each cell type. Studied as a function of temperature, antibody-induced redistribution of sIgM on cells previously exposed to LPS was observed to occur at temperatures lower than the temperatures required for similar sIgM redistribution on lymphocytes not exposed to LPS. In contrast, mitogen-treated sIgG⁺ cells demonstrated an opposite and long-lasting effect (at least 40 hr), requiring higher temperatures to allow sIgG movement comparable to that seen on untreated sIgG-bearing lymphocytes. Thus, we conclude that LPS interacts with both IgM⁺(IgG^?) and IgG⁺ lymphocytes, but that such interactions produced different membrane effects on each B-cell subset. This membrane change can therefore be useful as a quasi-functional differentiation marker. Furthermore, differences in sensitivity to cellular activation by LPS seen between sIgM-bearing (sIgG^?) and sIgG-bearing B cells may be a reflection of such direct, although different, membrane effects.     

A silver stain for the detection of nanogram amounts of tRNA following two-dimensional electrophoresis

Three ultrasensitive protein silver-staining methods have been compared with respect to the detection of tRNA in polyacrylamide gels. The method of Sammons (D. W. Sammons, L.D. Adams, and E.E. Nishizawa (1981) Electrophoresis 2, 135-141) has been shown to have remarkable sensitivity, with a detection limit of 0.3 ng tRNA/mm2, allowing the two-dimensional fractionation of submicrogram amounts of bulk tRNA. The application of this technique to developmental and differentiation problems and other areas where the amounts of nonradioactive tRNA available are limited is anticipated.     

Suppressive effects of soluble histocompatibility antigens on the in vitro generation of cytotoxic T cells to D-end alloantigens

Murine histocompatibility antigens were solubilized from the spleens and lungs of C57BL/6 (H-2b) animals with hypertonic salt (3 M KC1). Aggregate-free soluble antigens were incubated with nonadherent lymph node cells from BALB/c (H-2d) mice for 18 hr prior to their use as responder cells in the mixed-lymphocyte reaction (MLR). It was found that the generation of cytotoxic cells was suppressed while the proliferative response was not affected. The observed suppression was not due to a shift in the kinetics of the generation of cytotoxicity as determined throughout a 10-day culture period. The suppression was specific in that the response in MLR to unrelated H-2f stimulator cells and the subsequent generation of cytotoxic cells were unchanged. Using various H-2 recombinant strains as target cells in the assay of cell-mediated lympholysis, suppression of cytotoxicity was observed when the D end, but not the K end, was shared with the C57BL/6 strain from which the antigens were derived.     

Seminalplasmin: A protein with many biological properties

Proteins present in the seminal plasma of mammals are known to influence functions associated with ejaculated spermatozoa such as motility, capacitation, acrosome reaction and fertilising ability. The proteins isolated and characterised so far influence only one of the above functions of spermatozoa. Seminalplasmin, a protein isolated from the seminal plasma of bull is exceptional in that it influences many of the above spermatozoal functions. It is also a potent antimicrobial protein and capable of lysing microbial and mammalian cells. The physiological function of seminalplasmin as nature's own antifertility agent is discussed.     

Integrated palaeoecological and historical data in the service of fine-resolution land use and ecological change assessment during the last 1000 years in Rõuge, southern Estonia

Aims Our aim is to reconstruct decadal scale development of historical landscapes during the last 1000 years by means of fossil pollen analysis of annually laminated lake sediments, and detailed historical maps and documents. Location Lake Rõuge Tõugjärv (Estonia), a small lake with annually laminated lake sediments situated in a dense prehistoric setting. Methods The chronology of the palaeodata is based on the annual laminations supported by AMS ¹⁴C and ²¹⁰Pb dating and ¹³⁷Cs, ²⁴¹Am, and spheroidal carbonaceous particle marker horizons. The time‐scale and resolution allows fine sampling (the pollen samples generally comprise 3.5 years) and vegetation change reconstruction. Relevant source area of pollen (RSAP) of the lake was estimated, and the statistical zonation, rate of change, palynological richness, and DCA and PCA ordinations were generated on the basis of the pollen data. The historical calibration data set (maps, numerical information on population, domestic stock, farmland division, etc.) is based on archival material preserved in the Estonian Historical Archives. Results The topmost part (0–180 cm) of the sediment column of Lake Rõuge Tõugjärv, covering the last 1000 years, is visibly laminated carbonaceous gyttja. The varve chronology extends from ad 2000 to ad 1339, with a cumulative ± 9‐year error estimate. Beyond this the chronology is extrapolated using the ¹⁴C date and varve age–depth estimations. The simulation of the RSAP of Lake Tõugjärv shows that the major portion of the pollen loading originating from local vegetation is derived from plants growing within 2000 m of the sampling site. The pollen record divides into five statistically significant subgroups, which fall on the PCA plot into three clusters reflecting the general openness–closedness of the landscape. During the period between ad 1000 and 1200 (RT 1) the Rõuge area was generally wooded with birch, spruce and pine forests. The advancement of extensive farming gradually opened up the landscape between ad 1200 and 1650 (RT 2 and RT 3). The maximum openness of the landscape was reached between ad 1650 and 1875 (RT 4), with the most open period in the late eighteenth century. Historical maps from 1684 and 1870–99 and available quantitative data on population, domestic stock, farmland division, etc. show the same trend. The pollen data covering the last 125 years, and maps from 1935 and 1995, show the reduction of arable land in RSAP of the lake under investigation and the reduction of open land to an extent comparable with the end of the seventeenth century. Main conclusions The formation and development of the cultural landscape at Rõuge over the last 1000 years is characterized by rapid changes in floristic richness and rates of vegetation change attributed to certain historic processes in the RSAP. Five phases of landscape and social development are clearly distinguished during the last 1000 years. The decadal scale vegetation response to human‐induced forcing agrees with historical maps and documents and could be used for past landscapes prior to the period with solid historical data.