The wonders of magnetism

In this acceptance address for the Bioelectromagnetics Society's 2001 d'Arsonval Award, Dr. Tenforde reviews the highlights of the nonionizing field aspects of his research and scientific service career. These are focused in four areas: (a). development and application of microelectrophoretic methods to probe the surface chemistry of normal and cancerous cells; (b). research on the biophysical mechanisms of interaction and the dosimetry of static and extremely low frequency magnetic fields; (c). application of extremely high intensity magnetic fields in several spectroscopic methods for probing the detailed structures of large biological macromolecules; and (d). development of national and international guidelines for the exposure of workers and members of the general public to electromagnetic fields with frequencies spanning the entire nonionizing electromagnetic spectrum.     

Latitudinal gradients of parasite richness: a review and new insights from helminths of cricetid rodents

The latitudinal diversity gradient (LDG), or the trend of higher species richness at lower latitudes, has been well documented in multiple groups of free‐living organisms. Investigations of the LDG in parasitic organisms are comparatively scarce. Here, I investigated latitudinal patterns of parasite diversity by reviewing published studies and by conducting a novel investigation of the LDG of helminths (parasitic nematodes, trematodes and cestodes) of cricetid rodents (Rodentia: Cricetidae). Using host–parasite records from 175 parasite communities and 60 host species, I tested for the presence and direction of a latitudinal pattern of helminth richness. Additionally, I examined four abiotic factors (mean annual temperature, annual precipitation, annual temperature range and annual precipitation range) and two biotic variables (host body mass and host diet) as potential correlates of parasite richness. The analyses were performed with and without phylogenetic comparative methods, as necessary. In this system, helminths followed the traditional LDG, with increasing species richness with decreasing latitude. Nematode richness appeared to drive this pattern, as cestodes and trematodes exhibited a reverse LDG and no latitudinal pattern, respectively. Overall helminth richness and nematode richness were higher in areas with higher mean annual temperatures, annual precipitation and annual precipitation ranges and lower annual temperature ranges, characteristics that often typify lower latitudes. Cestode richness was higher in areas of lower mean annual temperatures, annual precipitation and annual precipitation ranges and higher annual temperature ranges, while trematode richness showed no relationship with climate variables when phylogenetic comparative methods were used. Host diet was significantly correlated with cestode and trematode species richness, while host body mass was significantly correlated with nematode species richness. Results of this study support a complex association between parasite richness and latitude, and indicate that researchers should carefully consider other factors when trying to understand diversity gradients in parasitic organisms.     

Dissymmetric recognition of the helical sense of deoxyribonucleic acid and evidence for binding of reporter molecules from the minor groove of DNA

Through the utilization of optically active DNP-derivatives of l- and d-proline, evidence is presented which suggests that nucleic acids exist as right-handed helices in solution. The results of ultraviolet absorption, circular dichroism, proton magnetic resonance (pmr), T_m of the helix-coil transition, viscometric, and binding studies are consistent with the above interpretation. It is shown that several types of DNA (i.e., salmon sperm, calf thymus, Micrococcus luteus, poly d(A-T)-poly d(A-T) and poly d(I-C)-poly d(I-C)) exist in a right-handed helical structure in solution. In addition, evidence is presented which strongly indicates that the 2,4-dinitroaniline ring of DNP-proline is intercalated between base-pairs of DNA and the prolyl side chain situated in the minor groove. Moreover, it is shown that the more sterically hindered DNP-derivatives exhibit a higher selectivity for A-T binding sites.     

25 Jahre Mykotoxin-Workshop

Mycotoxin research has a long tradition in Germany and is documented by a series of annual meetings which started 25 years ago. This paper gives an historical review on these Mycotoxin-Workshops. The first mycotoxin workshop in 1979 at the Federal Centre for Meat Research in Kulmbach was initiated by the former Federal Ministry of Agriculture and mainly thought to bring together scientists from the Federal research facilities. Main topics at that early time of mycotoxin research were food and feed safety, the mycology of toxin producers, the analysis and toxicology of mycotoxins. In the following years the Mycotoxin Workshop was influenced not only by working groups from the Federal research facilities but also from universities, state laboratories, other organisations and research scientists from outside Germany and with different disciplines. The number of participants increased from 19 at the beginning to more than 150 up to now and in order to organise these annual meetings at varying locations, in 1997 the society for mycotoxin research was founded. Since that time the Society for Mycotoxin Research (www.mykotoxin.de) is responsible for the organisation of the Mycotoxin Workshops. In addition the Society for Mycotoxin Research organizes the Brigitte Gedek science award, endowed with ￠ 10,000, and the Münchner Mycotoxin fellowship program, both intented to promote scientific research in mycotoxinology.

Presented at the 25^th Mykotoxin Workshop in Giessen, Germany, May 19–21, 2003     

《生物工程学报》30年

回顾了《生物工程学报》伴随着我国生物工程学科成长与发展的30年。从《生物工程学报》与相关成果、与学科发展、与知名科学家的关系等几个方面进行了概述,并对未来发展作了思考。     

The influence of aging on androgen dynamics in the male rat

Androgen assimilation was investigated in a variety of accessory sex organs (seminal vesicles and anterior, dorsal, lateral, and ventral prostates) and in several nonaccessory sex organs in male Wistar rats. After administration of a pulse dose of [³H]testosterone in vivo to intact young (3–4 months old) rats, [³H]testosterone was the primary radioactive steroid recovered from most organs examined, except for the secondary sex glands where the reduced metabolites, [³H]5α-dihydrotestosterone (DHT) and [³H]5α-androstanediol(s), predominated. At longer postinjection times, [³H]DHT was preferentially retained in the accessory sex glands, presumably reflecting intracellular metabolism of [³H]testosterone to this compound and subsequent specific binding of [³H]DHT to receptor proteins. At the longest postinjection interval investigated, the ventral prostate retained greater concentrations of [³H]DHT than the lateral prostate which in turn had a higher [³H]DHT concentration than the seminal vesicles or anterior or dorsal prostates. The latter three glands retained approximately equal concentrations of [³H]DHT. Scatchard plot analyses of cytosol binding in 24-h castrates indicated that with one exception, the level of high affinity DHT binding sites was generally correlated with the retention of [³H]DHT in vivo in intact rats. Specifically, while the affinity for DHT binding in all accessory sex organs was the same, the number of high affinity binding sites per mg wet tissue weight was on the order of ventral prostate > anterior prostate ≥ seminal vesicles ≥ dorsal prostate > lateral prostate. Studies of the influence of aging to 22–26 months revealed no apparent differences in the affinity of the DHT receptor for its ligand in any of the accessory sex glands from 24-h castrates when the receptors were present in levels sufficiently high to quantify. The concentration of available DHT receptors with advancing age remained constant in the anterior and dorsal prostates, increased in the seminal vesicles, and declined in the ventral and lateral prostates. The decreases observed in the ventral prostate were only partial, but the receptors of the lateral prostate declined to nondetectable levels.