Ecological theories and Dutch nature conservation

This paper aims to achieve insight into various ecological theories in the Netherlands which have different, and sometimes opposing, views on the conservation of nature. Interviews, publications and archival research brought to light four separate theories: vitalistic/holistic, dynamic, cybernetic and chaos. Diversity is reached through stability according to vitalistic/holistic and cybernetic theories, but through change and instablility according to the dynamic and chaos theories. These two groups are working apart, and continue to have their own ideas. Prediction of the future is only possible with the vitalistic/holistic and cybernetic theories. Ecologists who adhere to these theories feel responsible and able in different ways to change ecological nature towards desirable end goals. The other two theories, dynamic and chaos, appear to be less activist.     

Relationships of Agropyron intermedium chromosomes determined by chromosome pairing and alcohol dehydrogenase isozymes in common wheat background

Summary The relationships of Agropyron intermedium chromosomes in two wheat-Agropyron addition series were determined. Chromosome pairing behaviour revealed that the alien chromosome in lines TAF-2 and L7 of Vilmorin-A. intermedium set are homologous to the alien chromosomes in lines P and C of the Caribo-A. intermedium set respectively. Localization of alcohol dehydrogenase isozyme genes in Vilmorin-Agropyron addition line L4 and in Caribo-Agropyron line O indicated relationships with wheat chromosomes of homoeologous group 4.     

Lysing of fresh human tumor by a cytotoxic factor derived from autologous large granular lymphocytes independently of other known cytokines

Summary During interaction with autologous tumor cells large granular lymphocytes (LGL) of cancer patients released a soluble cytotoxic factor, termed LGL-derived cytotoxic factor, which mediated lysing of autologous fresh tumor cells. The cytotoxic factor was compared with purified human recombinant cytotoxic cytokines, including tumor necrosis factor (TNF), lymphotoxin (LT), interferon (IFN) , IFN, interleukin-1 (IL-1) and IL-2. The LGL cytotoxic factor exhibited cytotoxicity against autologous and allogeneic fresh human tumor cells in an 18-h⁵¹Cr-release assay, while these target cells were resistant to lysing by any of the recombinant cytokines. Mixtures of recombinant(r) TNF, rLT, rIFN, rIFN, rIL-1 and rIL-2 were still unable to produce cytotoxic effects on fresh human tumor cells. Treatment with monoclonal and polyclonal antibodies directed against rTNF, rLT, rIFN, rIFN, or rIL-1 did not inhibit the cytotoxic activity of LGL-derived cytotoxic factor against fresh human tumor cells. Even a mixture of all the antibodies was incapable of blocking the cytolytic activity of the factor to fresh human tumor cells. Furthermore, intact LGL-mediated lysing of autologous tumor cells was not inhibited by any of the antibodies. These results may indicate that a cytotoxic factor produced by LGL in response to autologous tumor cells mediates lysing of fresh human tumor cells independently of TNF, LT, IFN, IL-1 and IL-2.     

Complete protection against melanoma in absence of autoimmune depigmentation after rejection of melanoma cells expressing α(1,3)galactosyl epitopes

The major barrier for xenotransplantation in humans is the presence of (1–3) Galactosyl epitopes (Gal) in xenogeneic tissue and the vast quantities of natural antibodies (Ab) produced by humans against this epitope. The binding of anti-Gal Ab to cells expressing Gal triggers a complement-mediated hyperacute rejection of target cells. The hyperacute rejection of whole cancer cells, modified to express Gal epitopes, could be exploited as a new cancer vaccine to treat human cancers. We tested this hypothesis in Galactosyltransferase knockout (GT KO) mice which, like humans, do not express Gal on their cell surfaces and can produce anti-Gal Ab. Forty-five percent of mice with preexisting anti-Gal Ab rejected Gal positive melanoma cells (B16Gal). These mice remained tumor-free for more than 90 days. The majority of control mice injected with B16Null, Gal negative cells succumbed to melanoma. The rejection of B16Gal induced strong long-lasting antitumor immunity against B16Null measured by the expansion of cytotoxic T lymphocytes. In addition, mice rejecting B16Gal were protected against melanoma since they survived a second rechallenge with B16Null. Protected mice developed antitumor immunity in the absence of autoimmune depigmentation (vitiligo). These results show that rejection of Gal positive melanoma cells can efficiently boost the immune response to other tumor associated antigens present in Gal negative melanoma cells. This study supports the concept of a novel anticancer vaccine to treat human malignancies.     

A model of associative memory in the brain

A model of associative memory for time varying spatial patterns is proposed and simulated on a digital computer. This is a network composed of many neuron-like elements, and shows an ability for associative memory similar to that of the brain.Suppose a number of sequences of spatial patterns are presented to this network, for example, 12345, ABC, and so on. Then, these patterns are memorized in the network. After that, if any part of one of these sequences, say 23, is presented to the circuit, the rest of the sequence, 45, is recalled following to it. It resembles to such a situation — if we hear a part of a melody which we have memorized in the past, the rest of the melody is recalled even after it is stopped half-way. Although the recalled patterns are not always 100% correct, they are not completely destroyed even if the presented patterns are imperfect.     

A structural model for elongation factor 1 (EF-1) and phosphorylation by protein kinase CKII

EF-1a binds aminoacyl-tRNA to the ribosome with the hydrolysis of GTP; the complex facilitates the exchange of GDP for GTP to initiate another round of elongation. To examine the subunit structure of EF-1 and phosphorylation by protein kinase CKII, recombinant , , and subunits from rabbit were expressed in E. coli and the subunits were reconstituted into partial and complete complexes and analyzed by gel filtration. To determine the availability of the and subunits for phosphorylation by CKII, the subunits and the reconstituted complexes were examined as substrates for CKII. Formation of the nucleotide exchange complex increased the rate of phosphorylation of the subunit and reduced the Km, while addition of to or the complex inhibited phosphorylation by CKII. However, a had little effect on phosphorylation of . Thus, the and subunits in EF-1 were differentially phosphorylated by CKII, in that phosphorylation of was altered by association with other subunits, while the site on was always available for phosphorylation by CKII. From the availability of the subunits for phosphorylation by CKII and the composition of the reconstituted partial and complete complexes, a model for the subunit structure of EF-1 consisting of (22)2 is proposed and discussed.     

Immunofluorescence localization of the epidermolytic toxin target in mouse epidermal cells and tissue

Summary An epidermolytic toxin target was observed in keratohyalin granules of sectioned epidermis by a direct fluorescence procedure using FTC-toxin, but not by an indirect procedure using sequential reaction with toxin, anti-toxin and FTC-secondary antibody. The investigation of the two procedures was extended to keratinocytes. A dispase digestion procedure yielded three fractions which corresponded to basal, spinous and granular cells according to biochemical and morphological criteria. It was shown that the direct and indirect procedures both detected the toxin target in the keratohyalin granules of granular cells, but that the indirect procedure was very insensitive. In control experiments, the profilaggrin of keratohyalin granules was detected readily in cells by a direct procedure using FTC-antiprofilaggrin but only weakly by an indirect double antibody procedure. Insensitivity to indirect procedures thus appears to be a particular property of the keratohyalin granule site. It was shown that the toxin target was readily accessible in permeable (trypsin-isolated) granular cells but inaccessible in impermeable (dispase-isolated) cells.     

Effect of starvation on the content of free amino acids in plasma of different breeds of hen

Summary Leghorn, Cornish and White Rock hens were subjected to starvation. Free amino acids were determined in blood samples taken after 48, 72 and 96 h of starvation. A progressive decrease in concentration of the majority of amino acids was found. Changes in amino acid concentrations during starvation were dependent on the breed of hen.     

Characterization of the effectors required for stable inheritance of Streptococcus pyogenes pSM19035-derived plasmids in Bacillus subtilis

The low-copy-number and broad-host-range pSM19035-derived plasmid pBT233 is stably inherited in Bacillus subtilis cells. Two distinct regions, segA and segB, enhance the segregational stability of the plasmid. Both regions function in a replicon-independent manner. The maximization of random plasmid segregation is accomplished by the recombination proficiency of the host or the presence of the pBT233 segA region. The segA region contains two open reading frames (or) [ and ]. Inactivation or deletion of or results in SegA^– plasmids. Better than random segregation requires an active segB region. The segB region contains two ors (or and or). Inactivation of either of the orfs does not lead to an increase in cell death, but or^– plasmids are randomly segregated. These results suggest that pBT233 stabilization relies on a complex system involving resolution of plasmid oligomers (segA) and on the function(s) encoded by the segB region.     

Organization of the nervous system of physonectid siphonophores

Summary An antiserum to the sequence Arg-Phe-amide (RFamide) was used to stain the nervous systems of various physonectid siphonophores. In the stem of Nanomia bijuga, this antiserum stained an ectodermal nerve net, which was interrupted, at regular intervals, by transverse collars of neurons. Injection of Lucifer yellow into the giant axon of the stem showed that this axon was dye-coupled to an ectodermal nerve net that resembled the RFamide-positive network. Ectodermal nets of neurons were also found in the pneumatophore, gastrozooids, tentacles and tentilla. At the junctions of the pneumatophore, the gastrozooids, the dactylozooids and the gonozooids with the stem, and at the junctions of tentacles and tentilla, collars or rings of neurons occurred. The stem was connected to the phyllozooids and nectophores by muscular lamellae, which were bordered by chains of neurons. At the margin of the nectophores, an immunoreactive nerve ring was found. Connected to this ring and located in theseitliche Zapfen (sidely-located patche), were two agglomerations of nerve cells. On the upper side of the bell margin, positioned at 90° relative to the seitliche Zapfen, a delta-shaped neuronal structure was found. This structure was connected to the nerve ring and was associated with a muscle, which ran a short distance along the exumbrellar surface.The nervous systems of Agalma elegans, Forskalia edwardsi, Forskalia leuckarti and Halistemma rubrum resembled that of Nanomia bijuga in all major respects.     

Modulation of natural killer activity by thymosin alpha 1 and interferon

Summary A single injection of -interferon (-IFN) (30 000 units/mouse), a major biological modifier of natural killer (NK) cytolytic activity, strongly stimulated NK activity in normal mice, as expected, while the same treatment did not statistically alter the NK response in cyclophosphamide (CY)-suppressed animals.We investigated the possibility of thymosin ₁ cooperating with -IFN in boosting NK activity in CY-suppressed animals.The results show that treatment with thymosin ₁ (200 g/kg) for 4 days, followed by a single injection of -IFN 24 h before testing, strongly restored NK activity in CY-suppressed mice. Thymosin ₁ was, moreover, able to accelerate the recovery rate of NK activity in bone marrow reconstituted murine chimeras.Taken together the data support the concept that the synergic effect between thymosin ₁ and -IFN could be the result of effects on differentiation of the NK lineage at different levels.     

Biometeorological comfort index

The paper aims to represent and scale biometeorological sensations through a thermal index which comprises the effects of temperature, humidity and wind. The cooling power of a measured combination of wind speed and air temperature is equated with that due to the combination of a reference wind speed (related to the air movement experienced by a person walking in still air), and a derived aerodynamic temperature. A biometeorological temperature which is the average of such an aerodynamic temperature and a conventionally measured wet bulb temperature is shown to afford a better measure of comfort in Spain than some other, alternative indices.     

Immature erythroid cells with novel morphology and cytoskeletal organization in adultXenopus

Summary Nucleated erythrocytes of non-mammalian vertebrates are a useful model system for studying the correlation between changes in cell shape and cytoskeletal organization during cellular morphogenesis. They are believed to transform from spheres to flattened discs to ellipsoids. Our previous work on developing erythroblasts suggested that pointed cells containing incomplete, pointed marginal bands (MBs) of microtubules might be intermediate stages in the larval axolotl. To test whether the occurrence of such pointed cells was characteristic of amphibian erythrogenesis, we have utilized phenylhydrazine (PHZ)-induced anemia in adultXenopus. In this system, circulating erythrocytes are destroyed and replaced by erythroblasts that differentiate in the blood, making them experimentally accessible. Thus, we followed the time-course of morphological and cytoskeletal changes in the new erythroid population during recovery. During days 7–9 post-PHZ, pointed cells did indeed begin to appear, as did spherical and discoidal cells. The percentage of pointed cells peaked at days 11–13 in different animals, subsequently declining as the percentage of elliptical cells increased. Since degenerating old erythrocytes were still present when pointed cells appeared, we tested directly whether pointed ones were old or new cells. Blood was removed via the dorsal tarsus vein, and the erythrocytes washed, fluorescently tagged, and re-injected. In different animals, 2–8% of circulating erythrocytes were labeled. Subsequent to induction of anemia in these frogs, time-course sampling showed that no pointed cells were labeled, identifying them as new cells. Use of propidium iodide revealed large nuclei and cytoplasmic staining indicative of immaturity, and video-enhanced phase contrast and anti-tubulin immunofluorescence showed that the pointed cells contained pointed MBs. The results show that pointed cells, containing incomplete, pointed MBs are a consistent feature of amphibian erythrogenesis. These cells may represent intermediate stages in the formation of elliptical erythrocytes.Abbreviations MB marginal band - MS membrane skeleton - PHZ phenylhydrazine     

A cyto-biochemical study of the ‘canal’ formation in the yeast cell wall

Summary A distinction between the chemical composition of ultrastructurally modified regions and the rest of the cell wall (canals) of the yeast Schwanniomyces occidentalis was shown by cytochemical staining of cell wall polysaccharides. The formation of canals was induced by cultivation of yeasts on hydrocarbons and was parallelled by the enhancement of -glucosidase, -glucanase and -mannosidase activities which were all capable of degrading cell wall polysaccharides. The presence of cycloheximide prevented canal formation. We assume that these hydrolases modified definite cell wall regions transforming them into canals.     

Evaluation of hydrophobicity versus chaperonelike activity of bovine alphaA- and alphaB-crystallin

Calf lens A-crystallin isolated by reversed-phase HPLC demonstrates a slightly more hydrophobic profile than B-crystallin. Fluorescent probes in addition to bis-ANS, like cis-parinaric acid (PA) and pyrene, show higher quantum yields or Ham ratios when bound to A-crystallin than to B-crystallin at room temperature. Bis-ANS binding to both A- and B-crystallin decreases with increase in temperature. At room temperature, the chaperone-like activity of A-crystallin is lower than that of B-crystallin whereas at higher temperatures, A-crystallin shows significantly higher protection against aggregation of substrate proteins compared to B-crystallin. Therefore, calf lens A-crystallin is more hydrophobic than B-crystallin and chaperone-like activity of -crystallin subunits is not quantitatively related to their hydrophobicity.     

An improved method,using saturating light pulses,for the determination of photosystem I quantum yield via P700+-absorbance changes at 830 nm

An improved method is introduced for the determination of the quantum yield of photosystem I. The new method employs saturating light pulses with steep rise characteristics to distinguish, in a given physiological state, centers with an open acceptor side from centers with a reduced acceptor side. The latter do not contribute to PSI quantum yield (_I). Oxidation of P700 is measured by a rapid modulation technique using the absorbance change around 830 nm. The quantum yield _I is calculated from the amplitude of the rapid phase of absorbance change (A; 830 nm) upon application of a saturation pulse in a given state, divided by the maximal A (830 nm) which is induced by a saturation pulse with far-red background illumination. Using this technique, _I can be determined even under conditions of acceptor-side limitation, as for example in the course of a dark-light induction period or after elimination of CO₂ from the gas stream. Thus determined _I values display a close-to-linear relationship with those for the quantum yield of PSII (_II) calculated from chlorophyll fluorescence parameters. It is concluded that the proposed method may provide new information on the activity of the PSI acceptor side and thus help to separate the effects of acceptorside limitation from those of cyclic PSI, whenever a non-linear relationship between _II and the P700-reduction level is observed.Abbreviations and Symbols A absorbance change - _I quantum yield of photosystem I - _II quantum yield of photosystem II - PAR photosynthetically active radiation This work was supported by the Deutsche Forschungsgemeinschaft (SFB 176 Molekulare Grundlagen der Signalübertragung und des Stofftransportes in Membranen and SFB 251 Ökologie, Physiologie und Biochemie pflanzlicher Leistung unter Streß).     

Characterization of human chromosomal unit fibers

A structural component of mitotic chromosomes that partially explains the compaction of DNA within mitotic chromosomes is suggested on the basis of the occurrence of long, regular cylindrical structures in preparations of isolated human chromosomes. These structures, unit fibers, of a rather constant diameter of about 4,000 Å have been postulated to be formed by coiling of the 250T2–300 Å solenoid chromatin fiber that itself is formed by coiling of the 100 Å string of nucleosome fiber. The human chromatid would thus be composed by a hierarchy of helices with contraction ratios for DNA at each level of coiling of 7 (string of nucleosomes), 5 (solenoid) and 40 (4,000 Å unit fiber or super-solenoid) which results in an overall contraction ratio for DNA in the unit fiber structures of about 1,400, which is approximately 5-fold less than the final contraction of DNA in intact chromatids of condensed metaphase chromosomes. The present report concerns more detailed studies with respect to the dimensions and cytochemical properties of the unit fiber structures observed in preparations of isolated human mitotic chromosomes that provide direct and indirect evidence in support of their super-solenoid structure and relate to known properties of human mitotic chromosomes.     

Nucellar callus of ‘Femminello’ lemon,selected for tolerance toPhoma tracheiphila toxin,shows enhanced release of chitinase and glucanase into the culture medium

Phoma tracheiphila is the causative agent of the disease mal secco. Citrus cultivars differ substantially in respect to their sensitivity to the pathogenP. tracheiphila and its toxin. Some cultivars (e.g., Femminello lemon) are inherently sensitive while others (e.g., Tarocco orange) are tolerant. Cell lines derived from nucellar tissue of Femminello, Tarocco and a cell line selected for tolerance to the fungal toxin (Femminello-S) were used to study host-pathogen interaction. Our results showed that calli or conditioned media of Tarocco and Femminello-S inhibited the size of co-cultivated fungal colonies when compared to Femminello. In addition, conditioned medium of Tarocco as well as FemminelloS, but not Femminello, promoted bursting of hyphal tips. A ten-fold increase in chitinase and glucanase enzymatic activity, as evaluated by radiometric assay and laminarin hydrolysis respectively, was detected in Femminello-S extracellular extracts as compared to Femminello. An increase in chitinase was also shown by immunoblot analysis. Our findings suggest a positive correlation between the presence of chitinase and glucanase in the conditioned media of the cultured cells and the tolerance of those cells toP. tracheiphila toxin.     

Yeast ribosomal proteins

Summary Homology maps between bacteriophages 81, 80 and were constructed on the basis of electron microscope observation of DNA heteroduplexes. In 81/80 heteroduplex, the left half and the right terminal region of 13% the total molecular length were highly homologous, while the remaining region covering the early gene cluster was entirely nonhomologous. In 81/ heteroduplex, high-degree homologies were detected at the left 14% terminal region covering the head gene cluster, the central 3.8% region covering the att-int-xis region and the 1.3% Q homology region. Low-degree homologies of shorter length were scattered at the tail gene cluster, b2 region, cIII region, PQ region and SR region. Comparing our results with the homology maps of other lambdoid phages reported by Simon et al. (1971) and Fiandt et al. (1971), a phylogenic relation of 81 to other lambdoid phages and the role of recombination in the course of divergence of lambdoid phages are discussed.     

Possible complex translocation t(9; 14; 13)(q12;pl?;q31) in mother of a child with 9p-trisomy syndrome

Summary A mentally retarded boy with trisomy 9p is described. This trisomy arose through aberrant segregation of translocation chromosome during meiosis in his mother, who has a complex translocation involving chromosomes 9, 13, and 14. Based on both G-, Q-banding, and DNA replication patterns, the patient's karyotype was identified as 47,XY,-13, +(9;13) (9pter9q12::13q3113qter), +t(13;14) (13pter13q31::14pl?14pter). We suppose his mother's karyotype to be 46,XX,-9,-13,-14,+t(9;13) (9pterq12::13q3113qter), +t(13;14) (13pter13q31::14pl?14pter), +t(9;14) (9qter9q12::14pl?14qter). His phenotypically normal brother and sister are also carriers, having the same translocation chromosome as their mother. Clinical findings of the patient included peculiar face with hypertelorism, prominent nasal bridge and deformed helix, marked delay of osseous development, hypoplastic phalangia in fingers and toes, dysplastic nails and absence of digital triradii.