Binding of the galactose-specificPseudomonas aeruginosa lectin,PA-I,to glycosphingolipids and other glycoconjugates

The carbohydrate-binding specificity ofPseudomonas aeruginosa lectin I (PA-I) in iodinated or biotinylated form was studied. A large number of glycosphingolipids, as well as some glycoproteins and neoglycoproteins were used as ligands. Also, inhibition by free saccharides of PA-I binding to glycosphingolipids was tested. It was found that the lectin binds most strongly to terminal and nonsubstituted Gal3Gal- or Gal4Gal-structures.Abbreviations PA-I Pseudomonas aeruginosa lectin I - Cer ceramide - lactosylceramide Gal4GlcCer - iso globotriaosylcerami Gal3Gal4GlcCer - globotriaosylceramide Gal4Gal4GlcCer - globoside or globotetraosylceramide GalNAc3Gal4Gal4GlcCer - Forssman glycolipid GalNAc3GalNAc3Gal4Gal4GlcCer - P1 glycolipid Gal4Gal4GlcNAc3Gal4GlcCer - lactoneotetraosylceramide Gal4GlcNAc3Gal4GlcCer - B5 glycolipid Gal3Gal4GlcNAc3Gal4GlcCer - gangliotetraosylceramide Gal3GalNAc4Gal4GlcCer - GM1 Gal3GalNAc4(NeuAc3)Gal4GlcCer - RBC red blood cells - BSA bovine serum albumin - PBS phosphate-buffered saline - SDS sodium dodecyl sulfate - TLC thin-layer chromatography - HPLC high pressure liquid chromatography - MS mass spectrometry - FAB fast-atom bombardment - EI electron impact     

Sialidase of swine influenza A viruses: variation of the recognition specificities for sialyl linkages and for the molecular species of sialic acid with the year of isolation

The sialidase of swine influenza A viruses of N1 and N2 subtypes, isolated from 1930 to 1992, was studied for substrate specificity with ganglio-series, lacto-series type II and GM3 gangliosides containing Neu5Ac2-3Gal, Neu5Gc2-3Gal and Neu5Ac2-6Gal linkages. All viral sialidases tested showed that the activity for hydrolysing substrates with Neu5Ac2-3Gal was higher than the activities with Neu5Gc2-3Gal and Neu5Ac2-6Gal linkages. When GM1b, GM3 and sialylparagloboside were used as substrates, the earliest strain (A/Wisconsin/15/30 H1N1, isolated in 1930) showed the activity ratio of Neu5Ac2-6Gal to Neu5Ac2-3Gal to be 0.13:0.2, and the ratio Neu5Gc2-3Gal/Neu5Ac2-3Gal to be 0.19:0.37, while those strains isolated from 1978 to 1992 exhibited ratios of 0.29:0.58 for Neu5Ac2-6Gal/Neu5Ac2-3Gal and 0.51:0.76 for Neu5Gc2-3Gal/Neu5Ac2-3Gal. The above results indicate that the substrate specificities of sialidases from swine influenza A viruses towards sialyl linkages and the molecular species of sialic acid are related to the year of isolation, i.e. strains isolated after 1978 exhibited higher activity towards Neu5Ac2-6Gal and Neu5Gc2-3Gal linkages when compared with strains isolated in an earlier year, 1930.Abbreviation Neu5Ac 5-N-acetylneuraminic acid - Neu5Gc 5-N-glycolyneuraminic acid - Gal d-galactose - Glc d-glucose - Cer Ceramide - II³(Neu5Ac)Lac Neu5Ac2-3Gal1-4Glc - GM3(Neu5Ac2-3Gal) Neu5Ac2-3Gal1-4Glc1-Cer - GM3(Neu5Gc2-3Gal) Neu5Gc2-3Gal1-4Glc1-Cer - GM1b(Neu5Ac2-3Gal) Neu5Ac2-3Gal1-3GalNac1-4Gal1-4Glc1-Cer - GMlb(Neu5Gc2-3Gal) Neu5Gc2-3Gal1-3GalNAc1-4Gal1-4Glc1-Cer - IV³(Neu5Ac)nLc4Cer Neu5Ac2-3Gal1-3GlcNAc1-4Gal1-4Glc1-Cer - IV³(Neu5Gc)nLc4Cer Neu5Gc2-3Gal1-3GlcNAc1-4Gal1-4Glc1-Cer - IV⁶(Neu5Ac)nLc4Cer Neu5Ac2-6Gal1-3GlcNAc1-4Gal1-4Glc1-Cer - TDC taurodeoxycholate.     

High D-glucose does not affect binding of α-tocopherol to human erythrocytes

The role of -tocopherol uptake system in human erythrocyte in the uptake of plasma -tocopherol has been suggested. However no information is available on -tocopherol uptake activity of human erythrocytes in the presence of high levels of D-glucose which is known to lead to pathological alterations in different cells including human erythrocytes. Therefore, in order to examine the effect of D-glucose on the binding of -tocopherol to human erythrocytes, the binding characteristics of -tocopherol to these cells were established first. Binding of [3H]-tocopherol to human erythrocytes was both saturable and specific. Scatchard analysis of -tocopherol binding to these cells showed the presence of two independent classes of binding sites with widely different affinities. The high affinity binding sites had a dissociation constant (Kd1) of 90 nM with a binding capacity (n1) of 900 sites per cell, whereas the low affinity binding sites had a dissociation constant (Kd2) of 5.2 M and a binding capacity (n2) of 105,400 sites per cell. Trypsin treatment abolished all the -tocopherol binding activity. Competition for the binding of -tocopherol to human erythrocytes was effective with other homologues of -tocopherol (-tocopherol, -tocopherol and -tocopherol) and their potency was almost equal to -tocopherol itself. The order of preference was -tocopherol > -tocopherol -tocopherol -tocopherol. Incubation of human erythrocytes with various concentrations of D-glucose did not affect -tocopherol uptake activity. Our data demonstrate the presence of an -tocopherol uptake system in human erythrocytes and that the -tocopherol uptake activity is not modulated by the presence of D-glucose.     

Genetics of resistance to Puccinia graminis tritici in ‘Chris’ and ‘W3746’ wheats

Summary Chris wheat possessed genes Sr5, Sr7a, Sr8a, Sr9g and Sr12. W3746, derived from the cross Chris/Baart, possessed Sr7a and Sr12. The response conferred by Sr7a was influenced by the genetic background. Although Sr7a or Sr12 alone conferred no observable resistance upon adult plants, the adult resistances of Chris and W3746 to predominant pathotypes appeared to be associated with the interaction of Sr7a and Sr12, or genes at closely linked loci.     

High-level Expression of Maize <Emphasis Type="Italic">γ</Emphasis>-zein Protein in Transgenic Soybean (<Emphasis Type="Italic">Glycine max</Emphasis>)

Primers were developed for 118 microsatellites isolated from grape (Vitis vinifera) genomic libraries enriched for (AC)n repeats. Only one microsatellite sequence matched other grape SSR-sequences in the GeneBank database. Genotyping was carried out in the parental lines and four offspring of two pseudo-test-cross populations, Cabernet Sauvignon x Seyval and Chardonnay x Bianca, and a further six other grape genotypes (V. vinifera Sultanina, Merlot, Syrah, Müller-Thurgau, Vitis Regent and V. riparia Gloire de Montpellier). A total of 108 microsatellites showed easily scorable alleles and 100 of them segregated according to a configuration suitable for mapping in either cross. A further 8 SSRs, although unsuitable for mapping in those crosses, showed polymorphism in the other genotypes tested. This set of markers was used, along with 75 microsatellites of other repeat-types, to fingerprint 46 offspring of the cross Chardonnay x Bianca. For each full-sib, individual heterozygosity and distance in repeat units between pairs of alleles at each locus (mean d²) were calculated as a tool for predicting highly outbred recombinant individuals. Six microsatellites with segregation ratios significantly distorted towards the lack of homozygous sibs were identified and mapped to linkage groups LG 3 and LG 5. Estimation of heterozygosity at genome-wide level and genotyping at loci for which homozygous sibs are discriminated against are discussed for marker-assisted background selection in outcrossing grapevines.     

Relationships between EUF-N fractions,N uptake and quality of sugar beet in deep loess soils of Southern Lower Saxony

Summary In field experiments conducted in 1981 on deep loess soils a significant correlation was obtained between EUF-N content in the topsoil and N in sugar beet roots as well as in whole plants. A very close correlation was found to exist between EUF-N values in June 1981 and -amino N in sugar beet roots at harvest. Also other quality criteria such as the contents of sugar, K and Na in roots and yield parameters correlated with EUF-N contents in topsoils.The inorganic and organic EUF-N fractions changed during the vegetation period due to both N uptake by the crop and mineralization. Therefore it appears to be expedient to use both fractions when calculating N fertilizer requirements.The correlation between EUF-N (topsoil samples drawn in the year preceding sugar beet) and sugar yield increases obtained by N fertilization that was found in Austria¹² was confirmed in our experiments with soils from Southern Lower Saxony.     

Restriction in the conformational flexibility of apoproteins in the presence of organic cosolvents: a consequence of the formation of "native-like conformation".

The influence of n-propanol on the overall -helical conformation of -globin, apocytochrome C, and the functional domain of streptococcal M49 protein (pepM49) and its consequence on the proteolysis of the respective proteins has been investigated. A significant amount of -helical conformation is induced into these proteins atpH 6.0 and 4°C in the presence of relatively low concentrations of n-propanol. The induction of -helical conformation into the proteins increased as a function of the propanol concentration, the maximum induction occurring around 30% n-propanol. In the case of -globin, the fluorescence of its tryptophyl residues also increased as a function of n-propanol concentration, the midpoint of this transition being around 20% n-propanol. Furthermore, concomitant with the induction of helical conformation into these proteins, the proteolysis of their polypeptide chain by V8 protease also gets restricted. The -helical conformation induced into - and -globin by n-propanol decreased as the temperature is raised from 4 to 24°C. In contrast, the -helical conformation of both - and -chain (i.e., globin with noncovalently bound heme) did not exhibit such a sensitivity to this change in temperature. However, distinct differences exist between the n-propanol induced -helical conformation of globins and the -helical conformation of - and -chains. A cross-correlation of the n-propanol induced increase in the fluorescence of -globin with the corresponding increase in the -helical conformation of the polypeptide chain suggested that the fluorescence increase represents a structural change of the protein that is secondary to the induction of the -helical conformation into the protein (i.e., an integration of the helical conformation induced to the segments of the polypeptide chain to influence the microenvironment of the tryptophyl residues). Presumably, the fluorescence increase is a consequence of the packing of the helical segments of globin to generate a native-like structure. The induction of -helical conformation into these proteins in the presence of n-propanol and the consequent generation of native-like conformation is not unique to n-propanol. Trifluoroethanol, another helix-inducing organic solvent, also behaves in the same fashion as n-propanol. However, in contrast to the proteins described above, n-propanol could neither induce an -helical conformation into performic acid oxidized RNAse-A nor restrict its proteolysis by proteases. Thus, the high sensitivity of apoproteins and the protein domains to assume -helical conformation in the presence of low concentration of n-propanol with a concomitant restriction of the proteolytic susceptibility of their polypeptide chain appears to be unique to those proteins that exhibit high -helical propensities. Apparently, this phenomenon of helix induction and the restriction of proteolysis reflects the formation of rudimentary tertiary interaction of the native protein and is unique to apoproteins or structural domains of -helical proteins. Consistent with this concept, the induction of -helical conformation into shorter polypeptide fragments of 30 residues, (e.g., _1-30, which exists in an -helical conformation in hemoglobin) is very low. Besides, this peptide exhibited neither the high sensitivity to the low concentrations of n-propanol seen with the apoproteins/protein domains nor the resistance toward proteolysis. The results suggest that the organic cosolvent induced decrease in the conformational flexibility of the apoprotein, and the consequent restriction of their proteolytic cleavage provides an opportunity to develop new strategies for protease catalyzed segment condensation reactions.     

Plant regeneration through culture of isolated microspores of Triticum aestivum L.

Wheat microspores mechanically isolated from the anthers before culture and isolated from the anthers during the hole culture period in a chemically defined medium resulted in proembryos, embryos and finally plants. Of the four genotypes included, all responded with proembryos, and the two spring wheats Ciano and Walter gave rise to macroscopic embryos and plants. The frequency of embryo regeneration and the frequency of albino plants in both Ciano and Walter was in accordance with previously obtained results with anther culture derived material.Abbreviations 2,4-d 2,4-dichlorophenoxy acetic acid - NAA 1-naphthaleneacetic acid     

Structures of the N-linked sugar chains in the PAS-6 glycoprotein from the bovine milk fat globule membrane

The structures of the N-linked sugar chains in the PAS-6 glycoprotein (PAS-6) from the bovine milk fat globule membrane were determined. The sugar chains were liberated from PAS-6 by hydrazinolysis, and the pyridylaminated sugar chains were separated into a neutral (6N) and two acidic chains (6M and 6D), the acidic sugar chains then being converted to neutral sugar chains (6MN and 6DN). 6N was separated into two neutral fractions (6N13 and 6N5.5), while 6MN and 6DN each gave a single fraction (6MN13 and 6DN13). The structure of 6N5.5, which was the major sugar chain in PAS-6, is proposed to be Man16 (Man13) Man14GlcNAc14GlcNAc-PA; 6N13, 6MN13 and 6DN13 are proposed to be Gal13Gal14GlcNAc12Man16 (Gal13Gal14GlcNAc12Man13) Man14GlcNAc14 (Fuc16)GlcNAc-PA;6M and 6D had 1 or 2 additional NeuAc residues at the non-reducing ends of 6MN13 and 6DN13, respectively. © 1998 Rapid Science Ltd     

A missense mutation (G197→A) in theα-l-fucosidase gene of fucosidosis patients leads to loss ofα-l-fucosidase

Fucosidosis is an autosomal recessive lysosomal storage disease resulting from the absence of -l-fucosidase activity. Two natural missense mutations (G¹⁹⁷A) and (A⁸⁶⁰G) within the -l-fucosidase gene have been reported to be homozygous in four patients with fucosidosis. Expression of wild-type and mutated -l-fucosidase cDNAs in COS-1 cells revealed complete deficiency of -l-fucosidase for the G¹⁹⁷A transition and a normal level of enzyme for A⁸⁶⁰G. We therefore conclude that the change of G¹⁹⁷A is responsible for fucosidosis in the patients while A⁸⁶⁰G is a normal polymorphic variant of -l-fucosidase.     

Efficient determination of angles subtended by Cα-Hα and N-HN vectors in proteins via dipole-dipole cross-correlation§

The angle CH,NHN subtended by the internuclear vectors 13C-H and 15N-HN in doubly-labeled proteins can be determined by observing the effect of cross-correlation between the dipolar interactions on zero- and double-quantum coherences involving 13C and 15N. Two complementary 2D experiments with the appearance of 15N-HN correlation spectra yield signal intensities that depend on the rate of interconversion through cross-correlated relaxation of in-phase and doubly antiphase zero- and double-quantum coherences. The ratio of the signal intensities in the two experiments bears a simple relationship to the cross-correlation rate, and hence to the angle CH,NHN. Assuming planarity of the peptide bond, the dihedral angle (between C and C) can be determined from the knowledge of CH,NHN. The experiments are very time-effective and provide good sensitivity and excellent spectral resolution.     

Genetic analysis of two wheat cultivars, ‘Sonalika’ and ‘WL 711’ for reaction to leaf rust (Puccinia recondita)

Summary Genetic analysis for leaf rust reaction of two widely adapted cultivars, Sonalika and WL 711, has been done using 21 near isogenic Lr lines and rust culture IL004 — avirulent on the two cultivars and all the Lr lines used. The segregation pattern in the F₂ generation indicated the presence of a recessive gene in Sonalika and of a dominant gene in WL 711. These genes in cultivars Sonalika and WL 711 have been identified as Lr 11 and Lr 13, respectively. Gene Lr 13 is no longer effective in WL 711 but it continues to give field resistance in the backgrounds of Chris, Prelude and Thatcher. There has been no significant change in the virulence spectrum of the leaf rust pathogen in India with the release of WL 711. High susceptibility of WL 711 seems to be due to the evolution of more aggressive forms of the pathogen to this cultivar. The gene Lr 11, which behaves as a recessive in Sonalika, was effective against leaf rust when this cultivar was released. The high susceptibility of Sonalika is probably due to an increase in the frequency of race 77 virulent on Lr 11. Lr 11 has shown a dominance reversal in the background of Sonalika. Present results suggest that interaction of resistance genes with the background genotype must be studied for their effective use in breeding programme.     

Effects of the ΔF508 mutation on the structure,function, and folding of the first nucleotide-binding domain of CFTR

The fatal autosomal recessive disease cystic fibrosis (CF) is caused by mutations in the gene which encodes the cystic fibrosis transmembrane conductance regulator (CFTR). Many of these disease-causing mutations, including the deletion of F508 (F508) which accounts for approximately 70% of the disease alleles, occur in one of the two consensus nucleotide binding sequences. Peptide studies have directly demonstrated that the N-terminal nucleotide binding sequences bind adenine nucleotides. Structurally, circular dichroism spectropolarimetry indicates that this region of CFTR assumes a -stranded structure in solution. The F508 mutation causes a diminution in the amount of -stranded structure and a concomitant increase in the amount of random coil structure present, indicating that either the mutant peptide has a different native structure or that the conformational equilibrium is shifted toward a more disordered form. Furthermore, the mutant peptide is more sensitive to denaturation, indicating that F508 is a stability, or protein-folding mutant. Here we review these results and discuss their implications for interpreting the behavior of F508in situ and for the rational design of new CF drugs.     

Microsatellite markers in the hexaploid Prunus domestica species and parentage lineage of three European plum cultivars using nuclear and chloroplast simple-sequence repeats

In a previous study, cDNA microsatellite markers were described in apricot (Prunus armeniaca L.). Specific PCR primers were designed to amplify the microsatellite-containing regions from genomic DNA in different Prunus species. In the present work, cDNA microsatellite markers were developed in the hexaploid Prunus domestica L. species and polymorphism was ascertained in a segregating plum population. Co-dominant mendelian segregation of alleles was demonstrated and microsatellite polymorphism displayed up to 6 alleles per SSR locus per individual. Parentage lineage of three full-sib European plum cultivars (cv. Cacanska najbolja, Cacanska rana and Cacanska lepotica) was reconstructed by the analysis of the above nuclear SSR markers, completed by four chloroplastic microsatellite loci. The six most informative nuclear loci enabled discrimination between the three Cacak cultivars and unrelated individuals as well as the previously proposed parents, Wangenheim and Pozegaca. Data obtained support previous evidence that these cultivars originated from the Stanley cultivar. However, SSR analysis finally excluded Wangenheim as the other possible parent. Based on the results obtained with nuclear and chloroplast SSR loci, we propose the origin of those three Cacak cultivars in a cross between Stanley as the mother plant and Ruth gerstetter as the pollinator. Furthermore, we demonstrate the utility of these apricot SSR markers for genotype fingerprinting of the hexaploid plum cultivars.     

Inactivation of DNA polymerases by adenosine 2′,3′-riboepoxide 5′-triphosphate allows estimation of the primers affinity

Template-primer dependent inactivation of human DNA polymerase and Klenow fragment of E. coli DNA polymerase I by adenosine 2,3-riboepoxide 5-triphosphate was used for quantitative analysis of the K_d values for oligonucleotide primers of different length. The K_d values are smaller by a factor of 2.5 than the K_m values for the same primers determined in the reaction of DNA polymerization in the case of DNA polymerase . The K_d and K_m values are nearly the same for Klenow fragment. Such approach to the determination of K_m/K_d ratio can likely be used for detailed quantitative analysis of DNA polymerases.Abbreviations epATP adenosine 2,3-riboepoxide 5-triphosphate - KF Klenow fragment of E. coli DNA polymerase I - Pol I E. coli DNA polymerase I - Pol human placenta DNA polymerase      

An investigation of the role of solutes in the xylem sap and in the xylem parenchyma as the source of root pressure

Summary Solute osmotic potentials (_x) in the vessels of hydroponically grown maize roots were measured to assess the osmotic-xylem-sap mechanism for generating root pressure (indicated by guttation). Solutes in vessels were measured in situ by X-ray microanalysis of plants frozen intact while guttating. Osmotic potentials outside the roots (_o) were changed by adding polyethylene glycol to the nutrient solution. Guttation rate fell when _o was decreased, but recovered towards the control value during 3–5 days when _o was greater than or equal to –0.3 MPa, but not when _o was equal to –0.4 MPa. In roots stressed to _o = –0.3 MPa, _x, was always more positive than _o, and _x changed only slightly (ca. 0.05 MPa). Thus the adjustment in the roots which increased root pressure cannot be ascribed to _x, contradicting the osmotic-xylem-sap mechanism. An alternative driving force was sought in the osmotic potentials of the vacuoles of the living cells (_v), which were analysed by microanalysis and estimated by plasmolysis. _v showed larger responses to osmotic stress (0.1 MPa). Some plants were pretreated with abundant KNO₃ in the nutrient solution. These plants showed very large adjustments in _v (0.4 MPa) but little change in _x (0.08 MPa). They guttated by 4 h after _o was lowered to –0.4 MPa. It is argued that turgor pressure of the living cells is a likely alternative source of root pressure. Published evidence for high solute concentrations in the xylem sap is critically assessed.Abbreviations _o external water potential - _x osmotic potential of xylem sap - _v osmotic potential of vacuolar sap - EDX energy dispersive X-ray microanalysis - CSEM cryo-scanning electron microscope - LN₂ liquid nitrogen - PEG polyethylene glycol     

The inheritance of host plant resistance and its effect on the relative infection efficiency of Magnaporthe grisea in rice cultivars

The inheritance of host plant resistance and its effect on the relative infection efficiency for leaf blast was studied in the crosses IR36/CO39 (partially resistant × highly susceptible) and IR36/IR64 (both partially resistant). On the natural scale, gene action appeared multiplicative. After log transformation, additive effects described most of the genetic variation in the cross IR36/CO39, while additive and dominance effects were about equal in magnitude in the cross IR36/IR64. Dominance was towards increased resistance. No transgressive segregation occurred in the cross IR36/CO39. The number of genes that reduce lesion number was estimated to be zero in CO39 and five or more in IR36. The cross IR36/IR64 showed transgressive segregation in both directions, and IR36 and IR64 each contain at least one gene that is not present in the other cultivar. The heritabilities (narrow sense) in the F₂ were low (range 0.06–0.16), while narrow sense heritabilities based on F₃ lines were much higher (range 0.41–0.68). Lesion numbers in F₃ lines were reasonably correlated with those in F₅ progenies derived from the same F₂ plant (r was±0.6 in both crosses). Partial resistance can be effectively improved by selecting the most resistant plants from the most resistant F₃ lines.     

Monoclonal antibody specific for α2→8-linked oligo deaminated neuraminic acid (KDN) sequences in glycoproteins. Preparation and characterization of a monoclonal antibody and its application in immunohistochemistry

Two particular types of sialoglycoproteins have been detected in fish: polysialoglycoproteins containing 28-linked polysialic acid (8Neu5Gc2) _n present in unfertilized Salmonidae fish eggs, and glycoproteins bearing oligo/polymers of deaminated neuraminic acids (KDN) found in the vitelline envelope of the eggs and ovarian fluid. We report the preparation and characterization of a monoclonal antibody specifically recognizing oligo/polymers of KDN sequences in glycoproteins and its application in immunohistochemistry. Fusion of spleen cells from a BALB/c mouse immunized with a KDN-rich glycoprotein (KDN-gp) containing (8KDN2) _n 6(KDN23Gal13GlNAc13) GalNAc1 residues, with mouse myeloma cells yielded a hybrid cell line producing a monoclonal antibody that bound to KDN-gp, but not to KDN-gp depleted of KDN residues. The specificity of the monoclonal antibody, designated mAb.kdn8kdn, was determined by an enzyme-linked immunosorbent assay using KDN-gp samples that varied in KDN content. These antigens were prepared by the selective removal of KDN residues from the native KDN-gp. The mAb.kdn8kdn reacted most strongly with the intact KDN-gp and less strongly with KDN-gp samples containing decreased numbers of KDN residues. The mAb.kdn8kdn was shown specifically to recognize the 28-linked oligo/polyKDN sequences, (8KDN2) _n , and to be able to distinguish specifically (8KDN2) _n chains from (8Neu5Ac2) _n and (8Neu5Gc2) _n chains. The antibody was used successfully for the immunohistochemical detection of reactive KDN epitopes in sections of paraffin embedded rat pancreas. Several controls verified the specificity of the immunohistochemical staining, thus providing the first demonstration of (8KDN2) _n sequences in a mammalian tissue. The mAb.kdn8kdn can now be used to search further for glycoconjugates containing (8KDN2) _n chains and will facilitate studies on their biosynthesis, intracellular localization and function.     

The final thermal preferendum of fishes: Shuttling behavior and acclimation overshoot

The concept of final preferendum is reexamined in light of data concerning acclimation in a cyclic thermal regime. Because of Shuttling behavior to temperatures above and below the mean preferendum, and because of faster acclimation upward than downward, which result in acclimation to a temperature exceeding the mean of the cycle, a fish may finally gravitate to a preferendum which does not equal acclimation temperature. It is suggested that a distinction be made between the crossover-point preferendum, where preference and acclimation are equal, and the ultimate preferendum to which a fish will ultimately gravitate.