Cytokine production in whole blood cell cultures of patients undergoing therapy with biological response modifiers or 5-fluorouracil

We have measured the levels of interferon (IFN), tumor necrosis factor (TNF), interleukin-1 (IL-1), IL-1, and IL-2 in the whole blood cell culture supernatants of 43 tumor patients undergoing a treatment with biological response modifiers or a conventional therapy with 5-fluorouracil and leucovorin. In the blood cell cultures of the 16 patients who received 5-fluorouracil and leucovorin IFN levels decreased (P0.01) and TNF levels rose (P0.05) during each therapy cycle. However, in the blood samples a declining number of total leukocytes and lymphocytes was measured (P0.05). Progressive disease could be correlated to a tendency towards lower IFN levels in the pretherapeutic cultures of these patients. The second group analyzed consisted of 8 patients receiving a low-dose IL-1 therapy. In this group we found either an unchanged or an augmented IFN production of the blood cells during treatment. In the group of 13 patients receiving low-dose recombinant IL-2 (4.5×10⁶IU m^–2 day^–1) significantly increasing IFN levels were seen in the blood cell cultures during the therapy (P0.05), although total leukocyte counts decreased. In this group, 4 had stable disease for at least 2 months and 9 patients had tumor progression under therapy. In the cultures of the latter a tendency towards lower IFN values was found. Finally, the cytokine production in the blood cell cultures of 6 patients receiving a combination therapy of IFN and high-dose IL-2 was studied. During this therapy a dramatically reduced production not only of IFN but also of all other measured cytokines was found. In this group all patients had tumor progression under therapy. It is concluded that the measurements of cytokine production in a reproducible whole blood culture system may be useful for monitoring immunological therapies and may help us to find out which doses of biological response modifiers have enhancing or suppressive effects on the functions of the immune cells.     

Molecular screening and fetal diagnosis of β-thalassemia in the Italian population

Summary This paper reports our experience of molecular screening and fetal diagnosis of -thalassemia in 457 at risk couples of Italian descent. Molecular screening was carried out by dot blot analysis on amplified DNA with oligonucleotide probes complementary to the eight most common mutations in Italians [39 (CT); 6 (-A); ⁺-87 (CG); ⁺ IVSI nt 110 (GA); IVSI nt 1 (GA); ⁺ IVSI nt 6 (TC); IVSII nt 1 (GA); ⁺ IVSII nt 745 (CG)]. By using this approach, we have been able to define the mutation in 92.8% of cases. The rest (all but four) were defined by direct sequencing and this led to the detection of nine rare mutations [76 (-C); ⁺ IVSI nt 5 (GA); ⁺ IVSI nt 5 (GC); ⁺ IVSI -1 (cod 30) (GC); ⁺-87 (CT), -290 bp del.; ⁺-101 (CT)], and to the characterization of a novel mutation consisting of the deletion of the G at the invariant AG of the IVSII splice acceptor site of the -globin gene ( IVSII nt 850-1 bp). In the remaining four cases, the -globin gene showed entirely normal sequences and the -globin gene cluster was intact, as indicated by Southern blot analysis. Fetal diagnosis was carried out by dot blot analysis with the oligonucleotide probes defined in the parents. The procedure is simple and reliable, and the results can be obtained within 1 week of sampling. No misdiagnosis has so far occurred. The results indicate that fetal diagnosis of -thalassemia by DNA analysis may be obtained in practically all cases (even in a population showing marked heterogeneity of -thalassemia) by the combination of dot blot analysis for detecting common mutations, and direct sequencing for defining those that are uncommon.     

Dry to wet weight biomass conversion constant for Tetrahymena elliotti (Ciliophora,Protozoa)

Summary The wet and dry weights of both axenic and monoxenic cultures of the ciliate Tetrahymena were determined directly. These estimates are dependent upon the method of volume determination. Assuming a prolate spheroidal shape for the ciliate, we calculate a mean wet weight of 0.4157±0.0713 pg m^-3 and a mean dry weight of 0.2793±0.0652 pg m^-3. Using electronic cell sizing, our estimates are 0.7869±0.1659 pg m^-3 and 0.5239±0.1101 pg m^-3, respectively. Independent of the method of volume determination, we estimate a mean biomass conversion ratio (dry weight/wet weight) of 0.59±0.08.     

Analysis of the 5′ flanking sequence of the Gγ globin gene by denaturing gradient gel electrophoresis confirms the heterogeneity of the Bantu βs haplotype

Summary The GCTT polymorphism recently described at positions — 1106 and — 1105 in the 5 flanking region of the G globin gene for the Bantu ^S haplotype was analysed by denaturing gradient gel electrophoresis. We studied 108 ^S chromosome and 122 ^A chromosomes. The TT sequence was found as follows: in all of 80 chromosomes bearing the Bantu ^S haplotype with the 6-bp deletion -400 nt from the G gene in 3 out of 5 Bantu ^S chromosomes without the deletion, in 1 out of 122 ^A chromosomes from different ethnic origins but in none of 23 ^S chromosomes bearing the Senegal, Benin or Cameroon haplotypes. These results confirm the heterogeneity of the Bantu ^S haplotype and allow a tentative evolutionary sequence for the different alleles at this locus to be presented.     

Theoretical studies on the necessary number of components in mixtures

Summary Theoretical studies on the necessary number of components in mixtures (for example multiclonal varieties or mixtures of lines) have been performed according to yielding ability. All theoretical investigations are based upon a Gram-Charlier frequency distribution of the component means with skewness ₁ and kurtosis ₂. The selected fraction p of the best components constitutes the mixture under consideration. The same selection differential S = S (p, ₁, ₂) can be realized by different parameter values of p, ₁ and ₂. Therefore, equal yield levels of the mixture can be achieved by different selected fractions p which implies different numbers of components in the mixture. Numerical results of S = S(p) for different values of ₁ and ₂ are presented and discussed. Of particular interest are the selected fractions p which lead to a maximal selection differential S. These results on S for large populations must be reduced in the case of finite population size. For this correction term we used an approximation B = B (p, n, ₁, ₂) given by Burrows (1972) where n = number of selected components. For given parameter values of ₁, ₂ and p, the necessary number n of components can be calculated by using the condition: Burrows-correction less than a certain percentage g of S — for example with g = 0.05 or g = 0.01. For given ₁ and ₂, the number n leading to a maximal selection differential S can be regarded as necessary number of components (necessary = maximum gain of selection under the given conditions). Numerical results are given for ₂ = 0 and for eight situations which are defined by linear relations ₂ = c ₁ between skewness and kurtosis. These cases will contain all possible numerical situations for ₁ and ₂, which may be relevant for practical applications. The necessary number of components turns out to be nearly independent of the numerical value of the kurtosis ₂. The n-intervals leading to selected fractions p from 0.01 to 0.20 approximately are: 2 n 4 for g = 0.05, 6 n 20 for g = 0.01 and 11 n 40 for g = 0.005, respectively. However, percentages g less than 0.01 would be unrealistically excessive. Therefore, following the assumptions and restrictions given in this paper one may conclude that n = 20 seems to be an appropriate upper bound for the necessary number of components in mixtures.     

The stimulation of methylmercury production by decomposition of flooded birch leaves and jack pine needles

The link between methylmercury (MeHg) production and decomposition of flooded organic matter was examined using an enclosure experiment. Six plastic enclosures were filled with lake water containing low concentrations of dissolved organic carbon (146µmolL^–1) and MeHg (0.02ngL^–1) and anchored in a lake at the Experimental Lakes Area, northwestern Ontario. Either fresh birch leaves, fresh jack pine needles, or no plant tissues at all were added to enclosures. Birch leaves decomposed 2.4 times faster than jack pine needles as measured by the total carbon decomposition by-products produced in enclosures over time. However, measured net MeHg production in enclosures containing birch leaves (0.35±0.05ng per g carbon added) was five times lower than in the enclosures containing jack pine needles (1.94±0.28ng per g carbon added). These results showed that MeHg production is not solely related to rates of organic matter decomposition, and that increases in MeHg associated with flooded birch leaves and jack pine needles resulted from the production of new MeHg as opposed to leaching of MeHg already in the plant tissues during decomposition.     

Susceptibility of clinical isolates of yeasts to anti-fungal agents

The antimicrobial activity of amphotericin B, 5-fluorocytosine, nystatin, clotrimazole and miconazole were compared in vitro against 244 strains of yeasts that had been isolated from clinical specimens. The yeasts used in this study included 20 species of Candida, Cryptococcus, Saccharomyces Geotrichum, Rhodotorula, Torulopsis and Trichosporon. The majority of the strains (78%) had an MIC of 0.5 g/ml for amphotericin B, 81% an MIC of 1 g/ml for 5-fluorocytosine, 99% 8 g/ml for nystatin, 91%, 8.0 g/ml for clotrimazole and 98% had an MIC of 4.0 for miconazole. Of the anti-fungal agents tested, 5-fluorocytosine and nystatin were found to have the greatest antifungal activity.     

Analogues of NADP+ as inhibitors and coenzymes for NADP+ malic enzyme from maize leaves

Structural analogues of the NADP⁺ were studied as potential coenzymes and inhibitors for NADP⁺ dependent malic enzyme from Zea mays L. leaves. Results showed that 1, N⁶-etheno-nicotinamide adenine dinucleotide phosphate ( NADP⁺), 3-acetylpyridine-adenine dinucleotide phosphate (APADP⁺), nicotinamide-hypoxanthine dinucleotide phosphate (NHDP⁺) and -nicotinamide adenine dinucleotide 2: 3-cyclic monophosphate (23NADPc⁺) act as alternate coenzymes for the enzyme and that there is little variation in the values of the Michaelis constants and only a threefold variation in V_max for the five nucleotides. On the other hand, thionicotinamide-adenine dinucleotide phosphate (SNADP⁺), 3-aminopyridine-adenine dinucleotide phosphate (AADP⁺), adenosine 2-monophosphate (2AMP) and adenosine 2: 3-cyclic monophosphate (23AMPc) were competitive inhibitors with respect to NADP⁺, while -nicotinamide adenine dinucleotide 3-phosphate (3NADP⁺), NAD⁺, adenosine 3-monophosphate (3AMP), adenosine 2: 5-cyclic monophosphate (25AMPc), 5AMP, 5ADP, 5ATP and adenosine act as non-competitive inhibitors. These results, together with results of semiempirical self-consistent field-molecular orbitals calculations, suggest that the 2-phosphate group is crucial for the nucleotide binding to the enzyme, whereas the charge density on the C₄ atom of the pyridine ring is the major factor that governs the coenzyme activity.Abbreviations NADP⁺ 1, N⁶-etheno-nicotinamide adenine dinucleotide phosphate - NHDP⁺ nicotinamide-hypoxanthine dinucleotide phosphate - APADP⁺ 3-acetylpyridine-adenine dinucleotide phosphate - SNADP⁺ thionicotinamide-adenine dinucleotide phosphate - AADP⁺ 3-aminopyridine-adenine dinucleotide phosphate - 23NADPc⁺ -nicotinamide adenine dinucleotide 2: 3-cyclic monophosphate - 3NADP⁺ -nicotinamide adenine dinucleotide 3-phosphate - 2AMP adenosine 2-monophosphate - 3AMP adenosine 3-monophosphate - 23AMPc adenosine 2: 3 monophosphate cyclic - A adenosine - RuBP ribulose 1,5-bisphosphate - SCF-MO Self-Consistent Field-Molecular Orbitals (method)     

Nuclear Overhauser effect investigation on GM1 ganglioside containingN-glycolyl-neuraminic acid (II3Neu5GcGgOse4Cer)

The conformational properties of the oligosaccharide chain of GM1 ganglioside containingN-glycolyl-neuraminic acid, -Gal-(1-3)--GalNAc-(1-4)-[-Neu5Gc-(2-3)]--Gal-(1-4)--Glc-(1-1)-Cer, were studied through NMR nuclear Overhauser effect investigations on the monomeric ganglioside in dimethylsulfoxide, and on mixed micelles of ganglioside and dodecylphosphocholine in water. Several interresidual contacts for the trisaccharide core--GalNAc-(1-4)-[-Neu5Gc-(2-3)]--Gal-were found to fix the relative orientitation of the three saccharides, while the glycosidic linkage of the terminal -Gal-was found to be quite mobile as the -Gal-(1-3)--GalNAc-disaccharide exists in different conformations. These results are similar to those found for two GM1 gangliosides containingN-acetyl-neuraminic acid and neuraminic acid [1].Abbreviations Ganglioside nomenclature is in accordance with Svennerholm [23] and the IUPAC-IUB Recommendations [24] GM3(Neu5Ac) II³Neu5AcLacCer, -Neu5Ac-(2-3)--Gal-(1-4)--Glc-(1-1)-Cer - GM3(Neu5Gc) II³Neu5GcLacCer, -Neu5Gc-(2-3)--Gal-(1-4)--Glc-(1-1)-Cer - GM1(Neu5Ac) II³Neu5AcGgOse₄Cer, -Gal-(1-3)--GalNAc-(1-4)-[-Neu5Ac-(2-3)]--Gal-(1-4)--Glc-(1-1)-Cer - GM1(Neu5Gc) II³Neu5GcGgOse₄Cer, -Gal-(1-3)--GalNAc-(1-4)-[-Neu5Gc-(2-3)]--Gal-(1-4)--Glc-(1-1)-Cer - GM1(Neu) II³NeuGgOse₄Cer, -Gal-(1-3)--GalNAc-(1-4)-[-Neu-(2-3)]--Glc-(1-1)-Cer - GD1a IV³Neu5AcII³Neu5AcGgOse₄Cer, -Neu5Ac-(2-3)--Gal-(1-3)--GalNAc-(1-4)-[-Neu5Ac-(2-3)]--Gal-(1-4)--Glc-(1-1)-Cer - GalNAc-GD1a IV⁴GalNAcIV³Neu5AcII³Neu5AcGgOse₄Cer, -GalNAc-(1-4)-[-Neu5Ac-(2-3)]--Gal-(1-3)--GalNAc-(1-4)-[-Neu5Ac-(2-3)]--Gal-(1-4)--Glc-(1-1)-Cer - Neu neuraminic acid - Neu5Ac N-acetyl-neuraminic acid - Neu5Gc N-glycolyl-neuraminic acid - Cer ceramide     

Impact of ethanol and acetaldehyde on DNA and cell viability of cultured neurones

Ethanol consumption has long been associated with brain damage. However, the mechanism underlying this deleterious effect remains unclear. Among different hypotheses, acetaldehyde is regarded by certain authors as playing a major role in the expression of ethanol toxicity, but there are still some uncertainties about the exact nature of its implication. We therefore tried to characterize the profile of the alterations of neuronal viability and DNA integrity obtained after either a direct exposure to ethanol or to acetaldehyde. Ethanol at concentrations within the range of blood alcohol levels in intoxicated humans (100 mmol/L) induced DNA alterations without any apparent effect on cell viability. Acetaldehyde ( 1000 mol/L) can also induce DNA alterations but with a different profile of the DNA cellular alterations. The comparison between the distributions of the comet tail DNA indicated that ethanol induced strong breaks (tail DNA 60 a.u.) generation whereas acetaldehyde rather induced lower breaks (20tail DNA 50 a.u.) formation but affecting a greater number of neurones. Acetaldehyde had thus a different genotoxic potential which may suggest a different mode of action or a different cellular target. Furthermore, when a single 100 mmol/L ethanol exposure did not lead to any loss of cell viability, the addition of an inhibitor of aldehyde dehydrogenase was followed by a significant loss in viability. In contrast, the inhibition of catalase, which suppresses acetaldehyde synthesis, led to no reduced viability in the same exposure conditions. ROS also reduced viability, but this was observed only after both cytochrome P450 stimulation and catalase inhibition. These combined results could suggest that acetaldehyde may play a significant role in the expression of ethanol toxicity in brain.     

Convergent synthesis of neoglycopeptides by coupling of 2-bromoethyl glycosides to cysteine and homocysteine residues in T cell stimulating peptides

The 2-bromoethyl -glycosides of the disaccharide galabiose [Gal(1-4)Gal] and the trisaccharides globotriose [Gal(1-4)Gal(1-4)Glc] and 3-sialyllactose [Neu5Ac(2-3)Gal(1-4)Glc] have been prepared by improved routes. The 2-bromoethyl glycosides were then used in cesium carbonate promoted alkylations of the sulfhydryl groups of cysteine and homocysteine residues in T cell stimulating peptides. This convergent and general approach was used to prepare 16 neoglycopeptides which were obtained in 52–95% yields after purification by HPLC. 1H NMR spectroscopy revealed that -elimination and epimerization of neoglycopeptide stereocentres did not occur during the synthesis.     

Average phase difference theory and 1∶1 phase entrainment in interlimb coordination

The dynamics of coupled biological oscillators can be modeled by averaging the effects of coupling over each oscillatory cycle so that the coupling depends on the phase difference between the two oscillators and not on their specific states. Average phase difference theory claims that mode locking phenomena can be predicted by the average effects of the coupling influences. As a starting point for both empirical and theoretical investigations, Rand et al. (1988) have proposed d/dt= — K sin ), with phase-locked solutions =arcsin( /K), where is the difference between the uncoupled frequencies and K is the coupling strength. Phase-locking was evaluated in three experiments using an interlimb coordination paradigm in which a person oscillates hand-held pendulums. was controlled through length differences in the left and right pendulums. The coupled frequency _c was varied by a metronome, and scaled to the eigenfrequency _v of the coupled system K was assumed to vary inversely with _c. The results indicate that: (1) and K contribute multiplicatively to (2) =0 or = regardless of K when =0; (3) 0 or regardless of when K is large (relative to ); (4) results (1) to (3) hold identically for both in phase and antiphase coordination. The results also indicate that the relevant frequency is _c/_v rather than _c. Discussion high-lighted the significance of confirming =arcsin(/K) for more general treatments of phase-locking, such as circle map dynamics, and for the 11 phase-entrainment which characterizes biological movement systems.     

A diallel cross for mating speeds inDrosophila melanogaster

A diallel cross inDrosophila melanogaster for the mating speeds of previously unmated pairs aged 6 days was carried out for 6 inbred lines and their hybrids. Pairs were observed for 40 minutes.There was extreme hybrid vigour especially in mating frequency for 10 minutes but the degree of hybrid vigour was relatively smaller for 40 minutes.Considerable variability occurred between the inbred lines indicating the genotypic control of mating speed.An analysis of variance on the hybrids revealed significant general and specific combining abilities, and reciprocal effects. The mating frequency for 10 minutes gave heritability in the narrow sense, h²=0.605, 20 minutes gave h²=0.510 and 40 minutes gave h²=0.342.The progressive reduction in h² is due to a decrease in additive genetic variance and an increase in dominance variance with time. Thus either the dominance relations of genes controlling mating speeds change with time. or different loci control this character at different times.     

Evolutionary temperature adaptation of fish sarcoplasmic reticulum

Summary Sarcoplasmic reticulum has been isolated from the white muscle of 15 species of teleost fish adapted to diverse thermal environments. Evidence has been obtained that the Ca²⁺-dependent ATPase of fish sarcoplasmic reticulum has undergone evolutionary modification for function at different temperatures. Compared with tropical fish, cold adapted species have higher rates of Ca²⁺ transport and Ca²⁺-ATPase activities at low temperatures. Most species have linear Arrhenius plots over the temperature range 0–30°C. Activation enthalpies (H ) of the ATPase ranged from 53–190 kJ mol^–1 and were positively correlated with environment temperature. Activation entropy (S ) varied from negative values in cold adapted species to positive values in tropical fish.In contrast to the Ca²⁺-ATPase, the basal ATPase of fish sarcoplasmic reticulum showed no relationship between either ATPase activity or thermodynamic activation parameters and environmental temperature.Only the Ca²⁺-dependent ATPase is coupled to Ca²⁺ transport. The percentage of total ATPase activity which is Ca²⁺ activated is higher at low temperatures in cold than in warm adapted species. For example, ratios of Ca²⁺-dependent/total ATPase at 2°C varied from 80–98% in Arctic, Antarctic and North Sea species to only 2–50% in various tropical fish. Above 20°C, similar ratios in the range 80–98% were obtained for all species. The nature of the basal ATPase and mechanisms of temperature adaptation of fish sarcoplasmic reticulum are discussed.Abbreviations ET environmental temperature - EGTA ethylene glycol-bis (-aminolethyl ether)-N, N-tetraacetic acid - HEPES N-2-hydroxylpiperazine-N-2-ethanesulfonic acid - SR sarcoplasmic reticulum     

Identification of beta subunit of the rhesus monkey chorionic gonadotropin (rmCG)

Chorionic gonadotropin (CG) is a placental derived hormone that plays a crucial role in successful implantation and establishment of early pregnancy in the primates. The rhesus monkey was chosen as a model to understand the feasibility of developing human DNA immuno-contraceptive. The coding region of rhesus monkey CG -subunit (rmCG) was isolated by the TDRT-PCR method. The nucleotide sequence including the leader peptide was 499 nucleotide long and encoded 166 amino acids. In comparing with the previous known primates CG -subunits, the rmCG was the highest degree of homology with baboon CG -subunit at the deduced amino acid sequence (94%), 79.5% homology with human CG -subunit and 70.4% homology with marmoset monkey CG -subunit. The eukaryotic expression vector pCMV4-rmCG inserted full-coding cDNA sequence of rmCG was constructed, and the expression of rmCG -subunit in HeLa cells transient expressing system in vitro and BALB/c mice in vivo was determined. The results demonstrated that the recombinant PCMV4-rmCG eukaryotic expression vector could express rmCG -subunit in vitro and in vivo.     

Die Richtungen des Nahrungsflusses im Darmtrakt der Kleinzikade Euscelidius variegatus KBM. (Jassidae)

Zusammenfassung Der Verlauf des Nahrungsflusses im Darmtrakt der Kleinzikade Euscelidius variegatus wird nach Verfütterung von farbstoffhaltiger Nährlösung ermittelt. Es wird der Beweis erbracht, daß die aufgenommene Nahrungsmenge in der Filterkammer geteilt wird und die beiden Anteile den Darmtrakt auf zwei verschiedenen Wegen in Richtung Rektalblase passieren. Ein Anteil der aufgenommenen Nährlösung wird über einen Kurzschlußweg in der Filterkammer sowohl über den Filterkammerdarm als auch über die Kryptonephridien direkt in den Enddarm gepumpt, während die in der Magentasche der Filterkammer verbleibenden Nahrungsanteile über einen langen Verdauungsweg zum After gelangen. Hierbei wird der Magentascheninhalt in den Magen gedrückt. Von dort aus passiert er den Mitteldarm und erreicht über den Enddarm den After. Der Kurzschlußweg und der Verdauungsweg können gleichzeitig benutzt werden. Der Kurzschlußweg wird von der Nahrung jedoch in viel kürzerer Zeit durchströmt als der längere Verdauungsweg.

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The directions of the flow of food in the alimentary trad of the leafhopper Euscelidius variegatus KBM. (Jassidae)

Summary The leafhopper Euscelidius variegatus is fed with synthetic food, coloured with 1% Azorubin-S. Its flow in the alimentary tract has been studied. It has been found that the sucked-in food is divided into two parts in the filter chamber, each taking different way in the alimentary tract for its flow. One part of the food is pumped into the hindgut via the short circuit way going through the filter chamber once over the Filterkammerdarm and also over the kryptonephries. That part of the food, which remains in the pocket of the filter chamber takes the long digestion way to the anus over stomach, midgut and hindgut. Both the ways could be used at the same time. But the food takes much shorter time for its passage through the short circuit way as compared to the time needed for the long digestion way.

     

Characterization of the MHC class II region in cattle. The number of DQ genes varies between haplotypes

The organization of the major histocompatibility complex (MHC) class II region in cattle was investigated by Southern blot analysis using human probes corresponding to DO, DP, DQ, and DR genes. Exon-specific probes were also employed to facilitate the assessment of the number of different bovine class II genes. The results indicated the presence of single DO and DR genes, at least three DR genes, while the number of DQ genes was found to vary between MHC haplotypes. Four DQ haplotypes, DQ ^{1 1} to DQ ^{2 4}, possessed a single DQ and a single DQ gene whereas both these genes were duplicated in eight other haplotypes, DQ ^{3 5} to DQ ^{9 12}. No firm evidence for the presence of bovine DP genes was obtained. The same human probes were also used to investigate the genetic polymorphism of bovine class II genes. DQ DQ , DR DR , and DO restriction fragment length polymorphisms (RFLPs) were resolved and in particular the DQ restriction fragment patterns were highly polymorphic. Comparison of the present result with the current knowledge of the class II region in other mammalian species suggested that the DO, DP, DQ, DR, and DZ subdivision of the class II region was established already in the ancestor of mammals. The DP genes appear to be the least conserved class II genes among mammalian species and may have been lost in cattle. The degree of polymorphism of different class II genes, as revealed by RFLP analyses, shows striking similarities between species.     

Essentialistisches und evolution?res Denken in der systematischen Ornithologie des 19. und 20. Jahrhunderts

Zusammenfassung Die Ablösung des essentialistischen (typologischen) Denkens bei Vertretern der systematischen Ornithologie durch das darwinistische (evolutionäre) Populationsdenken um die letzte Jahrhundertwende bildete eine scharfe historische Diskontinuität. Die essentialistische Denkweise, die in Europa während des 19. Jahrhunderts dominierend war, erreichte ihr Ende im Werk vonOtto Kleinschmidt (1870–1954), dem letzten Vertreter derPallas-Schlegel Schule. In den ersten Jahrzehnten dieses Jahrhunderts wurde die evolutionäre Denkweise der Ornithologen der nordamerikanischenBaird-Coues Schule und der europäischenSeebohm-Harter Schule bestimmend. Die weite taxonomische Begrenzung von Arten durch die Ornithologen der essentialistischenPallas-Schlegel Schule und der evolutionären Mikrotaxonomie täuscht Gemeinsamkeiten dieser Schulen vor; im theoretischen Denken ihrer Vertreter bestanden fundamentale Unterschiede. Gegenwärtig ist eine Entwicklung innerhalb der evolutionären Mikrotaxonomie erkennbar, die möglicherweise in naher Zukunft zu einer Trennung in zwei Schulen mit verschiedenen Artkonzepten und unterschiedlicher Artabgrenzung führen wird: (a) Weite Artabgrenzung (mit relativ wenigen polytypischen Arten) und (b) enge Artabgrenzung (mit relativ vielen monotypischen Arten). Dazwischen vermitteln intermediäre Vorschläge. Der wissenschaftliche Naturschutz bezieht sich heute auf evolutionär signifikante Einheiten und ist unabhängig von den verschiedenen systematischen Konzeptionen über die Art.

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Essentialistic and evolutionary thinking in the field of systematic ornithology during the 19^th and 20^th century

Essentialistic thinking dominated systematic ornithology in North America during the first half of the 19^th century and in Europe until the beginning of this century, when evolutionary thinking superseded it marking a sharp historical discontinuity. Evolutionary thinking of the ornithologists of the North AmericanBaird-Coues school and of the EuropeanSeebohm-Hartert school prevailed increasingly from the late 19^th century and early 20^th century onward, respectively. The representatives of the essentialisticPallas-Schlegel school and of evolutionary microtaxonomy delimited species taxa broadly which common procedure concealed the fundamental differences in their theoretical thinking. Within the near future, evolutionary microtaxonomy may split into two different schools supporting different species concepts and a different delimitation of species taxa: (a) Wide species limits resulting in relatively few polytypic species taxa and (b) narrow species limits resulting in numerous monotypic species taxa; intermediate views connect these extremes. Conservation biology refers to evolutionarily significant units and is independent of the different views of systematists as to what constitutes a species.

     

Cell recycling studies for α-amylase production by Bacillus amyloliquefaciens

Production of -amylase by a strain of Bacillus amyloliquefaciens was investigated in a cell recycle bioreactor incorporating a membrane filtration module for cell separation. Experimental fermentation studies with the B. amyloliquefaciens strain WA-4 clearly showed that incorporating cell recycling increased -amylase yield and volumetric productivity as compared to conventional continuous fermentation. The effect of operating conditions on -amylase production was difficult to demonstrate experimentally due to the problems of keeping the permeate and bleed rates constant over an extended period of time. Computer simulations were therefore undertaken to support the experimental data, as well as to elucidate the dynamics of -amylase production in the cell recycle bioreactor as compared to conventional chemostat and batch fermentations. Taken together, the simulations and experiments clearly showed that low bleed rate (high recycling ratio) various a high level of -amylase activity. The simulated fermentations revealed that this was especially pronounced at high recycling ratios. Volumetric productivity was maximum at a dilution rate of around 0.4 h^–1 and a high recycling ratio. The latter had to exceed 0.75 before volumetric productivity was significantly greater than with conventional chemostat fermentation.List of Symbols a proportionality constant relating the specific growth rate to the logarithm of G (h) - a ₁ reaction order with respect to starch concentration - a ₂ reaction order with respect to glucose concentration - B bleed rate (h^–1) - C starch concentration (g/l) - C ₀ starch concentration in the feed (g/l) - D dilution rate (h^–1) - D _E volumetric productivity (KNU/(mlh)) - e intracellular -amylase concentration (g/g cell mass) - E extracellular -amylase concentration (KNU/ml) - F volumetric flow rate (l/h) - G average number of genome equivalents of DNA per cell - k _l intracellular equilibrium constant - k ₂ intracellular equilibrium constant - k _s Monod saturation constant (g/l) - k ₃ excretion rate constant (h^–1) - k _d first order decay constant (h^–1) - k _gl rate constant for glucose production - k _st rate constant for starch hydrolysis - k _t1 proportionality constant for -amylase production (gmRNA/g substrate) - k ₁ translation constant (g/(g mRNAh)) - KNU kilo Novo unit - m maintenance coefficient (g substrate/(g cell massh)) - n number of binding sites for the co-repressor on the cytoplasmic repressor - Q repression function K₁/K₂Q1.0 - R ratio of recycling - R _s rate of glucose production (g/lh) - r _c rate of starch hydrolysis (g/(lh)) - R _eX retention by the filter of the compounds X: starch or -amylase - r intracellular -amylase mRNA concentration (g/g cell mass) - r _C volumetric productivity of starch (g/lh) - r _E volumetric productivity of intracellular -amylase (KNU/(g cell massh)) - r _r volumetric productivity of intracellular mRNA (g/(g cell massh)) - r _e volumetric productivity of extracellular -amylase (KNU/(mlh)) - r _s volumetric productivity of glucose (g/(lh)) - r _X volumetric productivity of cell mass (g/(lh)) - S ₀ free reducing sugar concentration in the feed (g/l) - S extracellular concentration of reducing sugar (g/1) - t time (h) - V volume (l) - X cell mass concentration (g/l) - Y yield coefficient (g cell mass/g substrate) - Y _E/S yield coefficient (KNU -amylase/g substrate) - Y _E total amount of -amylase produced (KNU) - substrate uptake (g substrate/(g cell massh)) - specific growth rate of cell mass (h^–1) - _d specific death rate of cells (h^–1) - _m maximum specific growth rate of cell mass (h^–1) This study was supported by Bioprocess Engineering Programme of the Nordic Industrial Foundation and the Center for Process Biotechnology, the Technical University of Denmark.     

Modelling of predator–prey trophic interactions. Part I: two trophic levels

A class of lumped parameter models to describe the local dynamics in a controlled environment of a two-trophic chain is considered. The class is characterized by a trophic function (functional response of predator to the abundance of prey) depending on the ratio of prey biomass x and a linear function of predator biomass y: f(qx/[(1-)k+y]), where q is the efficiency of the predation process, k is a reference biomass, and (01) specifies the predation model. The trophic function is defined only by some properties determining its shape. A stability analysis of the models has been performed by taking the parameters q and as bifurcation parameters: the regions in the (,q) plane of existence and stability of nonnegative equilibrium states and limit cycles are determined. This analysis shows that the behaviour of the models is qualitatively similar for 0<1 (in particular the null state is always a saddle point), while the value =1 gives rise to some kind of structural instability of the system (in particular the null state becomes an attractor for sufficiently high predation efficiency).