Effects of Nucleotides on [3H]Bradykinin Binding in Guinea Pig: Further Evidence for Multiple B2 Receptor Subtypes

Abstract: We have suggested recently the existence of three subtypes of B₂ bradykinin receptors in tissues of guinea pigs. We have classified these B₂ bradykinin receptors into B_2a, B_2b, and B_2c subtypes depending on their affinity for various bradykinin antagonists. Because the actions of bradykinin in different cell systems appear to be both dependent on and independent of G proteins, we sought to determine whether the binding of [³H]bradykinin to the B₂ subtypes is sensitive to guanine nucleotides and, therefore, possibly coupled to G proteins. In the ileum, where we have demonstrated B_2a and B_2b subtypes, specific [³H]bradykinin binding was reduced with GDP (100 μM) and the nonmetabolized analogue of GTP, guanyl-5′-yl-imidodiphosphate (GppNHp; 100 μM). Competition studies with bradykinin and with [Hyp³]-bradykinin, which shows approximately 20-fold greater selectivity for the B_2a subtype than bradykinin, were performed in the presence or absence of GppNHp (100 μM). The competition experiments demonstrated that binding to the B_2a subtype, which has higher affinity for [Hyp³]-bradykinin and bradykinin than the B_2b subtype, was lost in the presence of GppNHp, whereas binding to the B_2b subtype was unaffected. In contrast, GppNHp (100 μM) and GDP (100 μM) failed to alter specific [³H]bradykinin binding to B_2b and B_2c subtypes in lung. [³H]Bradykinin binding was unaffected by AMP, ADP, ATP, and GMP (100 μM each). Based on this evidence, we suggest that the B_2a bradykinin subtype is coupled to G proteins. The B_2b and B_2c subtypes are either not coupled to G proteins, or may be coupled to the G^o-type GTP binding proteins, which have been suggested to be less sensitive to guanine nucleotides. These data provide further evidence for three subtypes of B₂-type bradykinin receptors in guinea pig.     

A molecular genetic linkage map of mouse chromosome 18, includingspm,Grl-1, Fim-2/c-fms,andMbp

Restriction endonuclease fragment length variations (RFLV) were detected in mice with DNA probes for myelin basic protein (Mbp), glucocorticoid receptor-1 (Grl-1), and Friend MuLV integration site-2 (Fim-2). RFLV of theMbp gene were found inSacI restriction patterns, RFLV of theGrl-1 gene were found inEcoRV patterns, and RFLV of theFim-2 were found inBglII patterns. A three-point backcross was carried out by the backcross mating (C57BL/KsJ-spm/spm × MOL-MIT)F₁ males × C57BL/KsJ-spm/spm; spm is an autosomal recessive gene causing sphingomyelinosis. From the results,spm, Grl-1, Fim-2, andMbp loci were mapped on chromosome 18, and the following order of genes is proposed, with distances between genes in parentheses: centromere—spm—(7.8 cM)—Grl-1—(7.8 cM)—Fim-2—(39.1 cM)—Mbp—telomere. All laboratory strains and two European subspecies (Mus mus domesticus andM. m. brevirostris) carry theGrl-1 ^a ,Fim-2 ^a , andMbp ^a alleles. In contrast, another wild subspecies from Europe (M. m. musculus) and some Asian subspecies (M. m. molossinus, Chinese mice of wild origin, andM. m. yamashinai) carry theGrl-1 ^b ,Fim-2 ^b , andMbp ^b alleles. Onlycastaneus strains carry the intermediate combination of theGrl-1 ^b ,Fim-2 ^a , andMbp ^b alleles.     

MHC recognition by clones of Mls specific T-lymphocytes

To test whether M1s determinants, like other non-MHC or nominal antigens, are recognized by T-cells in association with H-2 determinants, the in vitro proliferative responses of T-cell lines and clones were studied. Lines and clones were prepared by soft agar cloning (B10.BR x BALB/c)F₁ (H-2^k/H-2^d, M1s^b/M1s^b) T-cells responding in a primary MLR to AKD2F1 (H-2^k/H-2^d, M1s^a/M1s^a) stimulator cells. All the T-cell clones obtained could respond equally well in a proliferative assay to the Mls^a determinant in association with the H-2 haplotype of either parent, i. e., DBA/2 (H-2^d, M1s^a), and AKR (H-2^k, M1s^a) both stimulated equally well. When the T-cell lines and clones were screened against stimulators from recombinant inbred (RI) strains, it became apparent that strains exhibiting the H-2^b, M1s^a genotype stimulated poorly or not at all. This shows that the T-cell response to M1s^a involves MHC recognition, and raises the possibility that the response to M1s^a can involve recognition of H-2 specificities shared between the H-2 ^k and H-2 ^d haplotypes.Abbreviations used in this paper MHC major histocompatibility complex - MLC mixed lymphocyte culture - IL-2 interleukin 2 - Con A concanavalin A - RI recombinant inbred Howard Hughes Medical Institute     

Leucine aminopeptidase polymorphism inPhaseolus and differential elimination of the donor parent genotype in interspecific backcrosses

Starch gel electrophoretic analysis of crude seed (cotyledonary) extracts of Phaseolus vulgaris, P. coccineus,F ₁ ,F ₂ ,F ₃ ,and reciprocal F ₁ backcrosses reveals monomorphic and polymorphic forms of leucine aminopeptidase (LAP) in the genus. The polymorphic forms (LAP-II) are controlled by the codominant alleles, Lap-II^a and Lap-II^b.Reciprocal backcrosses to both species show a highly significant deviation from the expected 1:1 ratio when the donor parent allele is transmitted through male gametes. There is not a significant deviation from the expected ratio when transmission is through female gametes. Differential gametic selection, in conjunction with differential sterility, suggests that structural differences exist between the genomes of these species. This research was supported in part by U.S. Public Health Service Grants GM 11612 and GM 14941-01.     

Genetic interaction between Non-MHC T- and B-cell alloantigens in response to rous sarcomas in chickens

Chickens of Regional Poultry Research Laboratory (RPRL) inbred line 6₃ regress sarcomas induced by Bryan high-titer Rous sarcoma virus to a greater extent than chickens of line RPRL 100, although these lines are identical for the major histocompatibility B complex. They differ, however, at three independent autosomal loci: Ly-4 and Th-1 determine the surface alloantigens of partly overlapping subsets of T lymphocytes, and Bu-1 determines a surface alloantigen of B lymphocytes. The association of genotypes at these loci with quantitative variation in their ability to regress Rous sarcomas was tested in segregating F₄ generation progeny derived from crosses of lines 100 and 6₃. The Ly-4 and Bu-1 genotypes showed association with Rous sarcoma regression, but the Th-1 genotype did not. Chickens of the Ly-4 ^a/Ly-4 ^a, Bu-1 ^b/Bu-1 ^b and Ly-4 ^b/Ly-4 ^b, Bu-1 ^a/Bu-1 ^a genotypes had a significantly higher regressor ability than the other two double homozygous genotypes. These results indicate that higher regression is associated with (1) interaction between the Ly-4 and Bu-1 loci, and (2) complementation between either the line 6 Ly-4 ^a allele and the line 100 Bu-1 ^b allele, or the line 100 Ly-4 ^b allele and the line 6 Bu-1 ^a allele.     

Inheritance pattern of downy mildew resistance in advanced generations of sorghum*

In a project aimed to incorporate downy mildew resistance into sorghum hybrid seed parents, we screened F₄ and F₅ families for resistance to the ICRISAT Centre isolate of the pathogen using a greenhouse seedling screening technique. The families originated from a cross of 296B (susceptible) and IS 18757 [(QL-3) resistant]. The F₄s were obtained from agronomic selection in F₂s and F₃s, and the F₅ families from advancing plants identified as resistant in segregating F₄ families. The resistant plants were more than double the number of susceptible plants in the F₄ and almost so in the F₅ suggesting that resistance to downy mildew was dominant. Of the four genetic models examined (a single-locus model and three two-locus models with complementary, inhibitory, and a combination of complementary and inhibitory interactions), the two-locus model with independent segregation and a combination of complementary and inhibitory inter-allelic interaction appeared to be most appropriate in explaining the segregation patterns within and among F₄ and F₅ families. Accordingly, for resistance to P. sorghi, the suggested genotypes for IS 18757 is Pl_aPl_aPl_bPl_b and for 296B is Pl_aPl_aPl_bPl_b.     

An Unbalanced Nested Model with Random Effects Having Unequal Variances

Consider the model Y_ijk=μ + a_i + b_ij + e_ijk (i=1, 2,…, t; j=1,2,…, B_i; k=1,2…,n_ij), where μ is a constant and a¹,b_ij and e_ijk are distributed independently and normally with zero means and variances σ²_ad_ij and σ², respectively, where it is assumed that the d_i's and d_ij's are known. In this paper procedures for estimating the variance components (σ², σ²_a and σ²_b) and for testing the hypothesis σ²_b = 0 and σ²_a = 0 are presented. In the last section the mixed model y_ijk, where x_ijkkm are known constants and β_m's are unknown fixed effects (m = 1, 2,…,p), is transformed to a fixed effect model with equal variances so that least squares theory can be used to draw inferences about the β_m's.     

Construction and properties of new Lyt-congenic strains and anti-Lyt-2.2 and anti-Lyt-3.1 monoclonal antibodies

Hybridomas producing mouse monoclonal IgM antibodies specific for Lyt-2.2 and Lyt-3.1 T-cell surface alloantigens have been constructed. Cytotoxic titers of ascites fluids were found to be 10^–6 or greater and no lysis of thymocytes of congenic strains bearing the alternative allele was observed at the lowest dilutions tested (12). The anti-Lyt-2.2 monoclonal antibody (HO-2.2) specifically precipiated from extracts of Lyt-2.2-positive thymocytes molecular species indistinguishable from those precipitated by conventional anti-Lyt-2.2 sera. However, by immunoprecipitation criteria (though not by cytotoxicity), the anti-Lyt-3.1 antibody (HO-3.1) demonstrated some cross-reactivity with similar molecular species from Lyt-3.1-negative thymocytes.In addition, three new strains of mice differing from existing strains in the region of theLyt-2 and4Lyt-3 loci have been constructed. They are: C.C58-Lyt-2^a, Lyt-3^a and C.AKR-Lyt-2^a, Lyt-3^a, congenic with Balb/cAn and bearingLyt-2 ^a andLyt-3 ^a alleles of C58/J and AKR/J, respectively; and AKR.C-Lyt-2^b, Lyt-3^b, congenic with AKR/J and bearing theLyt-2 ^b andLyt-3 ^b alleles of Balb/cJ.Abbreviations used in this paper DMSO dimethylsulfoxide - NP40 Nonidet P-40 detergent - SaCI Staphylococcus aureus, Cowan I strain - SDS sodium dodecyl sulfate - PAGE polyacrylamide gel electrophoreses - NP-NET buffer 0.15 M NaCl, 0.005 M EDTA, 0.05 M Tris, 0.02% sodium azide, pH 7.4, containing 0.5% or 0.05% NP40 as stated in text     

Isolation,structural and toxicological characterization of three new mycotoxins produced by the fungusAureobasidium pullulans

3 substances, B₁, B₂, and E₁ were isolated from culture medium extracts ofAureobasidium pullulans by reversed phase liquid chromatography and subsequent liquid chromatographic purification steps on silica gel. The 3 compounds inhibited the metabolism ofSaccharomyces cerevisiae and showed toxic effects in the growth inhibition test toEscherichia coli andBacillus subtilis. Elementary analysis and mass spectroscopical methods revealed sum formulas of C₂₃H₂₂O₆, C₂₂H₂₀O₆ and C₂₄H₂₈O₃ for B₁ B₂, and E₁ and molecular weights of 394, 380, and 364, respectively. Mass spectroscopical, UV-, IR-,¹³C-NMR, and¹H-NMR-spectroscopical investigations revealed polycyclic, non-aromatic compounds containing several carbonyl functions and double bonds and, most notably, spiroepoxy-functions, in the case of B₁ and B₂.     

The falcifolia syndrome of Oenothera: III. The general pattern of its non-Mendelian inheritance

Summary The falcifolia (fal) syndrome is a malformation characterized by shoot sectors with sickle-shaped leaves, which appears in hybrids between Oenothera suaveolens and O. lamarckiana and shows a non-chromosomal inheritance of a previously undescribed type. The determinants, their location in the cell, and the mechanism of their expression are unknown. The defect is the result of a cross in which mixing of two different cytoplasms occurs, without the usual predominantly maternal inheritance. F₁ progeny of reciprocal crosses show a quantitative difference in the frequency and degree of expression of the fal character. When the F₁ progeny are backcrossed to the parents, the percentage of fal is high in crosses to O. suaveolens and low in those to O. lamarckiana. This manner of transmission is observed regardless of whether the hybrid is used as seed or pollen parent or shows a normal or fal phenotype. F₂ generations from F₁ plants having either a normal or a fal phenotype always include a certain percentage of fal plants, although the latter generally produce a higher percentage of fal progeny. If a second backcross is carried out, plants that produce normal progeny on self-pollination behave differently from those that produce some fal off-spring when selfed. The latter are similar to the F₁ with regard to the transmission of the fal trait. Plants of the F₁B₁ yielding normal progeny upon selfing produce normal progeny in the F₁B₂ if the parent to which they are backcrossed is the same as in the first backcross; if the parents of the first and second backcross differ, a high percentage of fal offspring is obtained. Again, whether the hybrid is used as seed or pollen parent is not relevant. Exceptions to this behaviour have been observed only rarely in that the character of the penultimate cross is retained. There is some evidence of somatic segregation of the fal determinants, since sister plants may react differently; this suggestion is supported by comparing the progenies of different branches of a self-pollinated fal plant of the F₁ generation.Abbreviations F₁, F₂, F₃, F₄ First through fourth filial generation, obtained by self-pollination - F₁B₁ First backcross generation, i.e. the F₁ was backcrossed to one of the original parents - F₁B₂ Second backcross generation, i.e. the F₁B₁ was backcrossed to one of the original parents - F₁B₃ Third backcross generation, i.e. the F₁B₂ was backcrossed to one of the original parents - (F₁B₁)D₁ Descendants obtained by self-pollination of a F₁B₁ plant; further generations obtained by self-pollination are designated as D₂, D₃, D₄ - (F₁B₁)D₁B₁ Descendant or generation obtained by a backcross of the D₁ of an F₁B₁. Backcrosses of the D₂ and D₃ are designated mutatis mutandis - (F₁B₁)D₁B₂ Generation obtained by a backcross of the (F₁B₁)D₁B₁     

TheH-2 class II genes and the susceptibility to the development of pulmonary adenoma in mice

To determine the locus in theH-2 complex that affects susceptibility to the development of pulmonary adenomas in mice,H-2 congenic and recombinant strains of mice with A/Wy, BALB/c, C3H, and B10 backgrounds were subjected to treatment with urethane. The average number and the incidence of adenoma foci were recorded five months after the treatment. InH-2 congenic strains on the A/Wy background, the average number of adenoma foci per mouse was significantly higher in mice of the A/Wy, A/J, and A-Tla ^b (H-2 ^a ) strains than in A.BY (H-2 ^b ) mice. In BALB/c and C3H congenic strains, the strains carrying theH-2 ^k haplotype were more susceptible than those carrying theH-2 ^b haplotype. InH-2 congenic strains on the B 10 background, the average number and incidence of foci was also higher in haplotypesa, h2, k, andj than in haplotypesb, s, f, d, r, h4, i3, i5, and4. The average numbers of adenoma foci in (A/J × A.BY)F₁ (H-2 ^a /H-2 ^b ) and (B10 × B10.A)F₁ (H-2 ^b /H-2 ^a ) were intermediate between the numbers in the parental strains. In [B10.A (4R) × B10.A (3R)]F₁ (H-2 ^h4 /H-2 ⁱ³ ) and [B10.A (4R) × B10.A (5R)]F₁ (H-2 ^h4 /H-2 ⁱ⁵ ), the numbers of adenoma foci were higher than in resistant parental recombinants. These patterns of response to urethane matched the patterns of the immune response to lactate dehydrogenase-B (LDH-B) and immunoglobulin gamma 2a (IgG2a) proteins. These differences between mice in their susceptibility to the development of pulmonary adenomas is probably due to the polymorphism of the class II genes in theH-2 complex.     

Synergistic promotion of gibberellin and cytokinin on direct regeneration of floral buds from in vitro cultures of sepal segments in sinningia speciosa hiern

Summary This study reports the direct regeneration of flower buds from cultured sepal segments of Sinningia speciosa Hiern. Two types of floral bud regeneration were observed: regeneration of floral buds only (designed as B^F) and regeneration of both floral and vegetative buds (designed as B^F+V). The capacity of B^F regeneration was closely related to the location of sepal segments and the concentration of exogenous gibberellin (GA₃) and cytokinin in the medium. On the medium containing 1.0mgl^−1 GA₃, the addition of 6-benzyladenine (BA) significantly increased the frequency of total flower bud (B^F+B^F+V) formation, with the frequency up to 91.5% in the presence of 0.4mgl^−1 BA. On the medium containing 0.1mgl^−1 BA, the addition of GA₃ also increased the frequency of total flower bud regeneration, with the frequency up to 74.3% in the presence of 1.0mgl^−1 GA₃, but no further increase in regeneration was observed when the GA₃ concentration was higher than 1.0mgl^−1. The capacity of B^F regeneration from different locations of sepal segments was differential. The adaxial part of sepal segments gave rise to the highest frequency of 56.7 and 84.3% for B^F and B^F+B^F+V, respectively.     

Photosynthesis performance in sweet almond [<Emphasis Type="Italic">Prunus dulcis</Emphasis> (Mill) D. Webb] exposed to supplemental UV-B radiation

Due to anthropogenic influences, solar UV-B irradiance at the earth’s surface is increasing. To determine the effects of enhanced UV-B radiation on photosynthetic characteristics of Prunus dulcis, two-year-old seedlings of the species were submitted to four levels of UV-B stress, namely 0 (UV-B_c), 4.42 (UV-B₁), 7.32 (UV-B₂) and 9.36 (UV-B₃) kJ m⁻² d⁻¹. Effects of UV-B stress on a range of chlorophyll (Chl) fluorescence parameters (FPs), Chl contents and photosynthetic gas-exchange parameters were investigated. UV-B stress promoted an increase in minimal fluorescence of dark-adapted state (F₀) and F₀/F_m, and a decrease in variable fluorescence (F_v, F_v/F_m, F_v/F₀ and F₀/F_m) due to its adverse effects on photosystem II (PSII) activity. No significant change was observed for maximal fluorescence of dark-adapted state (F_m). Enhanced UV-B radiation caused a significant inhibition of net photosynthetic rate (P _N) at UV-B₂ and UV-B₃ levels and this was accompanied by a reduction in stomatal conductance (g _s) and transpiration rate (E). The contents of Chl a, b, and total Chl content (a+b) were also significantly reduced at increased UV-B stress. In general, adverse UV-B effects became significant at the highest tested radiation dose 9.36 kJ m⁻² d⁻¹. The most sensitive indicators for UV-B stress were F_v/F₀, Chl a content and P _N. Significant P<0.05 alteration in these parameters was found indicating the drastic effect of UV-B radiation on P. dulcis.     

H-2-associated differences in androgen-influenced organ weights of a and C57BL/10 mouse strains and their crosses

The influence ofH-2 haplotypes (in three-month-old males) on body weight, vesicular gland, testes, and thymus weight was investigated in A, B10, and B10.A strains and their respective F₁, F₂, and Bc progeny. The influence of theH-2 haplotypes was found to contribute to heterosis in the body weight.H-2 ^a/H-2 ^a males have a smaller vesicular gland and larger testes and thymus weight thanH-2 ^b/H-2 ^b males when groups with an identical or comparable genetic background are compared.H-2 heterozygous classes are closer to the parental strain with higher values for absolute organ weight; for relative organ weight, the heterozygous classes are intermediate or closer to the parental strain with lower values. This complex situation results from the simultaneous action ofH-2 haplotypes on both organ weight (Hom-1 effect) and body weight (heterosis), which probably operate through different mechanisms. Coat color genes were found to modify the penetrance ofH-2 influence on quantitative traits.     

Linked epistasis for six quantitative traits in Indian mustard (Brassica juncea (L.) Czern & Coss)

Summary Gene effects, and interactions, and associations between days-to-flower initiation and maturity, number of secondary branches and siliquae per plant, and 1,000-seed weight and yield per plant were studied in a cross of Indian mustard (Brassica juncea (L.) Czern & Coss) using the parents and F₁, F₂, F₃, B₁, B₂, B₁₁, B₁₂, B₂₁, B₂₂, B_1S, B_2S, B₁F₁, B₂F₁, B_1bip, B_2bip, F₂P₁, F₂F₁, and F_2bip generations. A linked digenic model was adequate for all characters studied. According to this model, the main effects, additive and interactions between linked pairs of genes, were present in varying proportions for days-to-flower initiation and maturity and number of siliquae per plant. The contribution of linked epistatic effects, however, was much greater than that of additive effects. Dominance effects contributed significantly to the inheritance of days-to-flower initiation. Duplicate epistasis was observed for all traits except 1,000-seed weight where epistasis was of the complementary type. A complete association among the genes of similar effect (increasing or decreasing) was observed for number of secondary branches and siliquae, and yield per plant. Coupling phase linkage was observed for days-to-flower initiation whereas repulsion phase linkage was observed for daysto-maturity and 1,000-seed weight.     

CML typing of serologically identicalH-2 mutants

Cell-mediated lympholysis (CML) reactions were studied among four strains of C57BL/6 (B6) mice carrying mutant alleles (H-2 ^ba ,H-2 ^bd ,H-2 ^bg , andH-2 ^bh ) at thez1 locus in theK end ofH-2 ^b and the original B6 (H-2 ^b ) strain. Cross killing of target cells from lines that had not participated in the mixed lymphocyte reaction (MLR) was extensive, but usually less intense than that of target cells of stimulator cell genotype. The extent of CML crossreactivity could be limited by using cells from F₁ hybrid mice as responders in MLR. In a comprehensive analysis of the cytotoxicity exerted by 20 MLR combinations with homozygous, and 10 MLR combinations with F₁ hybrid responder cells, 19 different CML cytotoxicity patterns were identified, corresponding to at least 19 different CML target specificites. When the number of CML mismatches of each mutant with the originalH-2 ^b was calculated,H-2 ^ba was found to be most distinct fromH-2 ^b ,H-2 ^bs andH-2 ^bd were closest toH-2 ^b , andH-2 ^bh occupied an intermediate position. The validity of this sequence of relatedness is supported by published reports on skin graft survival times and on the interaction of T lymphocytes with virus-infected target cells using cells fromz1 locus mutants.     

Quantitative genetics of growth and development in Populus. I. A three-generation comparison of tree architecture during the first 2 years of growth

One approach to gain an insight into the genetics of tree architecture is to make use of morphologically divergent parents and study their segregating progeny in the F₂ and backcross (B₁) generations. This approach was chosen in the present study in which material of a three-generation pedigree growing side by side in a replicated plantation, was analyzed. The pedigree included Populus trichocarpa (T) and P. deltoides (D) parents, their F₁ and F₂ hybrids and their B₁ hybrids to the D parent. The trees were grown in the environment of the T parent and measured for the first 2 years of growth. Nine quantitative traits were studied at the stem, branch and leaf levels of tree architecture, in which the original parents differed. Strong F₁ hybrid vigor relative to the better parent (T) was expressed in growth and its components. Most quantitative traits in the F₂ and B₁ hybrids were intermediate between the T and D parents but displayed a wide range of variation due to segregation. The results from the analysis of variance indicated that all morphometric traits were significantly different among F₂ and B₁ clones, but the B₁ hybrids were more sensitive to replicates than the F₂. Broad-sense heritabilities (H ²) based on clonal means ranged from moderately high to high (0.50–0.90) for the traits studied, with H ² values varying over age. The H ² estimates reflected greater environmental noise in the B₁ than in the F₂, presumably due to the greater proportion of maladaptive D alleles in those hybrids. In both families, sylleptic branch number and length, and leaf size on the terminal, showed strong genetic correlations with stem growth. The large divergence between the two original parents in the traits studied, combined with the high chromosome number in Populus (2n=38), makes this pedigree well suited for the estimation of the number of quantitative trait loci (QTLs) underlying quantitative variation by Wright's biometric method (1968). Variation in several traits was found to be under the control of surprisingly few major QTLs: 3–4 in 2nd-year height and diameter growth, a single QTL in stem diameter/height ratio.     

Measurement of the chlorophyll fluorescence induction kinetics with a 10 µs time resolution and its application in the forest decline research

Summary Measurement methods are described which determine the initial phase of the fluorescence induction kinetics with a maximum time resolution of 10 µs simultaneously for the two fluorescence componentsF ₆₈₅(t) andF ₁₃₀(t) selected by filters at the wavelengths 685 nm and 730 nm, respectively. The excitation light provided by a He-Ne laser (632.8 nm) is switched on within 0.3 µs (maximum intensityI _e=12 mW/cm²).F _o,F _p, andF _s, the initial-, peak-, and steady-state intensity and the initial valueR _o of the ratioR(t)=F ₇₃₀(t)/F ₆₈₅(t) can accurately be determined as well as the initial time derivativeF _o ^* of the fluorescence intensity.F _o andF _o ^* are related to the quantum yield _a of the antenna and to the photochemical quantum yield _pc, respectively. Spruce, oak, birch, poplar, and soy bean show a decline ofR(t) fromR _o to a first minimumR _b at some 10 ms which has a similar value as the second minimumR _p in the time range of seconds. Furthermore, the initial valueR _o and the steady-state valueR _S ofR(t) are also very similar. Measurements on spruce with water deficiency and with varying excitation light intensityI _e show effects on the initial phase of the fluorescence induction kinetics. Further measurements on spruce of different damage classes indicate that for the current year's needles the ratioF _p/F_o, is the most sensitive parameter to differentiate between the damage classes and thatF _o/F_s andR _o/R_b are also affected. As demonstrated by measurements on leaves of soy beans, the initial decrease ofR(t) fromR _o toR _b originates from a change of the fluorescence spectrum because no change of the leaf transmission can be observed in the time range between 10 µs and 1 ms.     

TheB locus (MHC) in the chicken: Association with the fate of RSV-induced tumors

The fate of tumors induced by Rous sarcoma virus (RSV) was determined in anF ₂ population segregating at three alloantigen loci. TheF ₁ resulted from crossing tumor-resistant RPRL line 6₁ (B ² B ² D ³ D ³ I ² I ²) with tumor-susceptible RPRL line 15₁ (B ⁵ B ⁵ D ⁴ D ⁴ I ⁸ I ⁸). Among theF ₂ segregantsB ² B ²,B ² B ⁵, andB ⁵ B ⁵, the percentage of chicks dying of terminal tumors (by 70 days post-inoculation) was 5, 26, and 93, respectively (P0.01). NeitherD orI genotypes nor sex significantly affected tumor growth. In chickens with terminal tumors, the incidence of metastatic lesions was also significantly associated withB genotypes. Thus, the MHC chromosomal region in the chicken appears to exert a crucial role in determining the outcome of RSV-induced tumors.     

Thirteen new chromosome-7 congenic lines

Thirteen new congenic lines have been produced which have chromosome-7 segments introduced from different strains onto the C57BL/10Sn background. Sublines B10.P(61NX)C,D, and E received chromosome-7 segments from P/J, B10.CE(62NX) from CE/J, B10.SEC(64NX)A,C,E, and F from SEC/1Re, B10.SM(65NX) from SM/J, B10.WB(66NX) from WB/Re, B10.A(67NX) from A/SnGrf, B10.AKR(68NX) from AKR/SnGrf, and B10.K(69NX) from C3H.K. Isograft testing indicated that three sublines, B10.P(61NX)D, B10.CE(62NX)B, and B10.WB(66NX)B are histoisogenic, i.e., histocompatible within each line. With the exception of B10.A(67NX), B10.AK(68NX), and B10.K(69NX), which have not been isografted, the remaining sublines showed residual heterozygosity on isografting. The three histoisogenic lines have undergone F₁ testing and have been found to possess theH-4 ^a allele and new and distinct alleles at theH-1 locus. They have been designated B10.P(61NX)-H-4^a H-1 ^d , B10.WB(66NX)-H-4^a H-1 ^e , and B10.CE(62NX)-H-4^a H-1 ^f . Direct exchange of grafts has indicated the following genotypes: B10.A(67NX)-H-4^a H-1 ^b , B10.AK(68NX)-H-4^a H-1 ^b , and B10.K(69NX)-F-4^a H-1 ^b . The B10.SEC(64NX) and B10.SM(65NX) sublines have not been typed completely forH-4 andH-1. F ₁ testing or direct exchange of skin grafts indicated that B10.P(61NX)-H-4^a H-1 ^d , B10.WB(66NX)-H-4^a H-1 ^e , B10.A(67NX)-H-4^a H-1 ^b B10.AK(68NX)-H-4^a H-1 ^b and B10.K(69NX)-H-4^a H1 ^b possess nonon-H-1 histocompatibility differences from the G57BL/10 background.