Genetic analysis of the coloured mutants ofAspergillus niger

Seven different classes of coloured mutants were produced in anAspergillus niger strain: brown (B), cinnamon (C), dark brown (DB), fawn (F), green (G), yellow (Y) and white (W). A few of these recurrent colour mutants were allelic and the rest was non-allelic. These were tested by complementation test in heterocaryons. A few colour mutants failed to form heterocaryons. The incompatibility is suggested to be under genetic control. Conidial size of the heterocaryotic heads was measured and found to be significantly larger than that of their parental homocaryons. It is believed that the larger size is due to heterocaryotic vigor manifested in the conidia from heterocaryotic mycelium. It is termed haploid inherited vigor.     

Complementation between mutants of Phycomyces deficient with respect to carotenogenesis

Summary White and red mutants of Phycomyces, derived from two independent wild types (yellow) by mutagenesis using nitrosoguanidine, either in a single step (26 white, 5 red mutants), or in two steps (10 white mutants, from one of the red mutants) were studied with respect to complementation in heterokaryons. The tests clearly establish the involvement of three and only three genes, here named carA, carB, and carB. The carA and the carR mutants are white, the carA mutants do not accumulate phytoene, the carB mutants do. The carR mutants are red and accumulate lycopene. The two step mutants are either carA and carR, or carB and carR double mutants. A few of the white mutants obtained in a single mutagenization step are affected in carA and carR. They may be polar mutants in an operon or accidental double mutants.     

Hypotheses Concerning Algal Adaptation to Periodic Environmental Factors

A new lower-dimension ecological–evolutionary model of algae was proposed to describe the simultaneous dynamics of variables (population biomass) and parameters (limits of the temperature tolerance interval [a – d, a + d]). In a given periodic temperature regime, the parameters tend to certain final values, which are called evolutionarily stable (ES) values. Calculations showed that ES parameters form a rainbow structure on the plane (a, d); the farthest points of the rainbow correspond to psychrophilic (diatom) and thermophilic (blue–green) algae. Algal adaptation to two periodic environmental factors, temperature and salinity, was carried out within preset temperature and salinity tolerance ranges [a – d, a + d] and [b – c, b + c]. The domain of evolutionarily stable parameters in the plane (a, b) was found to depend on the degree of synchronism of environmental factors. The parameters lay on a linear segment in some cases, while their location on a nonlinear oval was unexpectedly possible in some other cases.

     

Immune responses in vitro

The Mls locus was originally defined to have four alleles; three controlled products that were detectable in primary mixed leukocyte reactions (MLR), whereas one, b, was described as being null. Recently, other investigators postulated that the Mls locus is nonpolymorphic, being composed of the b null allele and of a singly expressed allele previously thought to be the a and d alleles. We previously reported that products controlled by Mls ^aand Mls ^dwere antigenically distinct and therefore are not controlled by the same allele, and the product of Mls ^bon cells of three different strains was easily detectable by Mls ^aand Mls ^dresponding cells. Thus the b allele is not null. In the present report evidence is presented which indicates that both Mls ^band Mls ^cencoded products were undetectable by MLR when in the presence of Mls ^aor Mls ^d. This was demonstrated by (a) the inability of Mls ^a/Mls ^cand Mls ^a/Mls ^bF₁ cells to stimulate Mls ^aresponding cells and Mls ^d/Mls ^cand Mls ^d/Mls ^bcells to stimulate Mls ^dcells; (b) the positive response of Mls ^a/Mls ^band Mls ^d/Mls ^bF₁-hybrid cells to Mls ^b-encoded products; and (c) the reactivity of Mls ^a/Mls ^cand Mls ^d/Mls ^cF₁ hybrid cells to Mls ^c-encoded determinants.     

Effects of Mutations at the W Locus (c-kit) on Inner Ear Pigmentation and Function in the Mouse

The W locus encodes a tyrosine kinase receptor, c-kit, which affects survivial of melanoblasts from the neural crest. The primary cochlear defect in Viable Dominant Spotting (W^v/W^v) mutants is a lack of melanocytes within the stria vascularis (SV) associated with an endocochlear potential (EP) close to zero and hearing impairment. In this study, we compare inner ear pigmentation with cochlear potentials in three other W alleles (W^x, W^sh, and W⁴¹) and reveal an unequivocal correlation between presence of strial melanocytes and presence of an EP. Asymmetry was common, and 8.3% of W^sh/W^x, 25% of W^sh/W^sh, 60% of W⁴¹/W^x, and 69.2% of W⁴¹/W⁴¹ ears had a pigmented stria and an EP, while the remainder had no strial melanocytes and no EP. In those mutants that partially escaped the effects of the mutation, strial melanocytes rarely extended the entire length of the stria, but were confined to the middle and/or basal turns of the cochlea. The extent of strial pigmentation was unrelated to the EP value, which was measured from the basal turn only. Compound action potential (CAP) responses recorded from ears with an EP were variable and they showed greatly raised thresholds or were absent in all ears where the EP was close to zero. In controls, melanocytes in the vestibular part of the ear were found in the utricle, crus commune, and ampullae, whereas in many mutants only one or two of these regions were pigmented. There was a broad correlation between pigmentation of the stria and pigmentation of the vestibular region but this was not absolute. All W⁴¹/W^x, W^sh/W^sh, and W⁴¹/W⁴¹ mutants had some pigment on the pinna but, in contrast to controls where melanocytes were found in the epidermis and dermis of the pinna, pigment cells were reduced in number and generally restricted to the dermis. Injection of normal neural crest cells into 9.5-day-old mutant embryos increased the extent of skin pigmentation on the head and coat of adult chimeras and was associated with a small increase in the proportion of pigmented strias.     

Identification of self-incompatibility genotypes of almond by allele-specific PCR analysis

In almond, gametophytic self-incompatibility is controlled by a single multiallelic locus (S-locus). In styles, the products of S-alleles are ribonucleases, the S-RNases. Cultivated almond in California have four predominant S-alleles (S ^a, S ^b, S ^c, S ^d). We previously reported the cDNA cloning of three of these alleles, namely S ^b, S ^c and S ^d. In this paper we report the cloning and DNA sequence analysis of the S ^a allele. The S^a-RNase displays approximately 55% similarity at the amino-acid level with other almond S-RNases (S^b, S^c, and S^d) and this similarity was lower than that observed among the S^b, S^c and S^d-RNases. Using the cDNA sequence, a PCR-based identification system using genomic DNA was developed for each of the S-RNase alleles. Five almond cultivars with known self-incompatibility (SI) geno-types were analyzed. Common sequences among four S-alleles were used to create four primers, which, when used as sets, amplify DNA bands of unique size that corresponded to each of the four almond S-alleles; S ^a (602 bp), S ^b (1083 bp), S ^c (221 bp) and S ^d (343 bp). All PCR products obtained from genomic DNA isolated from the five almond cultivars were cloned and their DNA sequence obtained. The nucleotide sequence of these genomic DNA fragments matched the corresponding S-allele cDNA sequence in every case. The amplified products obtained for the S ^a- and S ^b-alleles were both longer than that expected for the coding region, revealing the presence of an intron of 84 bp in the S ^a-allele and 556 bp in the S ^b-allele. Both introns are present within the site of the hypervariable region common in S-RNases from the Rosaceae family and which may be important for S specificity. The exon portions of the genomic DNA sequences were completely consistent with the cDNA sequence of the corresponding S-allele. A useful application of these primers would be to identify the S-genotype of progeny in a breeding program, new varieties in an almond nursery, or new grower selections at the seedling stage. Received: 21 June 1999 / Accepted: 15 November 1999     

茶树品种(品系)芽叶色泽表型遗传数量分类研究

为探讨茶树春梢芽叶色泽的数量遗传特性,应用色差仪测定68份茶树品种(品系)春梢芽叶的色泽表型值并进行数量分类研究。结果表明,对叶色差异度较高的第1叶位L~*、a~*、b~*、C、H值进行分层聚类分析,可将芽叶色泽划分为紫色系、黄色系和绿色系等7个色系。色系分类与CIELab颜色体系的对应性较强,色系划分符合茶树品种(品系)叶色表型特点。茶树品系的叶色表型较丰富,叶色在L~*、a~*、b~*值三维坐标空间整体呈带域分布,色系由紫色系、紫红色系、紫绿色系向黄色系、黄绿色系、绿色系变化。春梢芽叶色泽表型数据的遗传数量分类与色系判定为茶树特异芽叶色泽育种提供科学依据。     

Radiation-induced human chromosome aberrations. II. Human in vitro irradiation compared to in vitro and in vivo irradiation of marmoset leukocytes

Whole blood cultures from humans and from the New World primate, Saguinus fuscicollis, were irradiated with various doses of 250 kV X-rays. The resulting centric ring plus dicentric aberration yields were fitted to the three models, Y = a+bD, Y = a+bD+cD², and Y = a+cD², by least squares regression. In both instances the best fit was to the model Y = a+bD+cD², with coefficients of the one- and two-track components for human and marmoset being: b = (0.78 ± 0.09)·10⁻³, c = (5.92 ± 0.31)·10⁻⁶, and b = (1.11 ± 0.36)·⁻³, c = (7.7 ± 1.7)·10⁻⁶, respectively.     

Phytotron cultivation of early barley mutants

Conclusions The authors have tried to gather data which permit some information on the between and within locus reactions of induced early barley mutants to different photo- and thermoperiods. Eight mutant cases, showing rather drastic earliness in field cultivation and representing three different gene loci, were examined in phytotron experiments according to routine methods of cultivation. One of the mutants, mat-a ⁸, has been released as an original Swedish barley variety under the name of Svalöf's Mari. In a previous publication (Dormling et al., 1966) this mutant was compared to its parent variety, Svalöf's Bonus, under 30 different climatic conditions. In the present investigation three photoperiods (24, 16 and 8 hours of artificial light) were combined with three suitable thermoperiods (20-15°, 20-10° and 15-10°C).The results indicate that photoperiodic insensitivity, with regard to ear formation and heading capacity, as well as kernel production, is of rather frequent occurrence in connection with drastically early mutants in barley. Four out of eight induced mutants give a more or less pronounced insensitivity. Three of the four insensitive mutants represent locus a, one belongs to locus b. Of the two c-mutants none was insensitive; both were on the contrary pronounced long-day types.Photo- and thermoperiods interact in various ways. This is especially clear in the c-mutants just mentioned, which have a high generative productivity and efficiency at continuous light and high thermoperiods. They produce no grain but considerable vegetative matter at 8 hours of light, independently of thermoperiod, as well as at 16 hours of light with high temperatures. In fact, mutants of loci a and c differ strikingly with regard to their relations to the climatic conditions applied. The insensitive mutant b ¹³ is remarkably similar to the mutant a ¹², but its resemblance to the sensitive mutants b ⁷ and b ¹⁰ of the same locus is evidenced by its high average internode number.It ought to be pointed out here that the mutants of the three gene loci analysed in this study can be distinguished phenotypically with regard to morphological as well as physiological properties, in the field as well as in phytotron cultivation. The c-mutants are especially characteristic. However, there also seem to be clear differences in reaction between the allelic mutants of a locus. In fact, all eight mutants studied seem to react more or less differently.The insensitive mutant a ⁸, which has been released into practice, is also widely used in recombination work, and successful segregates have been isolated. The characteristics of a ⁸, which make the mutant valuable in practice, are also found in phytotron experimentation, specially with regard to earliness, generative efficiency and yield. Also the semidwarf habit and the insensitivity to changes in photo- and thermoperiods readily show up.This investigation has been generously supported by the Swedish Research Council of Forestry and Agriculture.     

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.     

Synthesis,characterization, and in vitro antimicrobial activities of 5-alkenyl/hydroxyalkenyl-2-phenylamine-1,3,4-oxadiazoles and thiadiazoles

The long-chain alkenoic acid hydrazides (1a–d) on reaction with phenylisocyanate and phenylthiocyanate gave their corresponding semicarbazides (2a–d) and thiosemicarbazides (4a–d), which on further refluxing with POCl₃ and Ac₂O yielded corresponding 1,3,4-oxadiazoles (3a–d) and thiadiazoles (5a–d), respectively.The structure elucidation of synthesized compounds is based on the elemental analysis and spectral data (IR, ¹H NMR, ¹³C NMR and MS). The synthesized oxadiazoles and thiadiazoles have been screened for antibacterial and antifungal activities. The investigation of antimicrobial screening revealed that compounds 3c, 3d, 5c, 5d and compounds 3b, 5b, showed good antibacterial and antifungal activities, respectively.     

Improvement of antagonistic capability of Trichoderma harzianum by UV-Irradiation for management of Macrophomina phaseolina

Antagonistic capability of Trichoderma harzianum was improved through UV-irradiation. Four different type of mutants, T. harzianum - M_a (Th-M_a), T. harzianum - M_b(Th-M_b), T. harzianum - M_c (Th-M_c), T. harzianum - M_d (Th-M_d) of T. harzianum and the parent strain (Th-P) were selected for further studies. Th-M_a and Th-M_b showed more antagonistic capability against Macrophomina phaseolina than its parent strain Th-P in dual culture. Biochemical analysis of these four mutants and the parent strain showed that Th-M_a releases higher level of two lytic enzymes i.e. chitinases and cellulases and Th-M_b produces more β-1,3-glucanase activity than the parent strain. Culture filtrate of Th-M_a also showed antifungal properties. Study of the competitive saprophytic ability (CSA) of these four mutants and the parent strain were also made. Th-M_a exhibited higher CSA than the parental isolate while Th-M_d had less CSA than all other mutants and the parent strain of T. harzianum.     

Involvement of oxidative stress in hydroquinone-induced cytotoxicity in catalase-deficient Escherichia coli mutants

Hydroquinone is a benzene-derived metabolite. To clarify whether the reactive oxygen species (ROS) are involved in hydroquinone-induced cytotoxicity, we constructed transformants of Escherichia coli (E. coli) strains that express mammalian catalase gene derived from catalase mutant mice (Cs^b, Cs^c) and the wild-type (Cs^a) using a catalase-deficient E. coli UM255 as a recipient. Specific catalase activities of these tester strains were in order of Cs^a > Cs^c > Cs^b > UM255, and their susceptibility to hydrogen peroxide (H₂O₂) showed UM255 > Cs^b > Cs^c > Cs^a. We found that hydroquinone exposure reduced the survival of catalase-deficient E. coli mutants in a dose-dependent manner significantly, especially in the strains with lower catalase activities. Hydroquinone toxicity was also confirmed using zone of inhibition test, in which UM255 was the most susceptible, showing the largest zone of growth inhibition, followed by Cs^b, Cs^c and Cs^a. Furthermore, we found that hydroquinone-induced cell damage was inhibited by the pretreatment of catalase, ascorbic acid, dimethyl sulfoxide (DMSO), and ethylenediaminetetraacetic acid (EDTA), and augmented by superoxide dismutase (both CuZnSOD and MnSOD). The present results suggest that H₂O₂ is probably involved in hydroquinone-induced cytotoxicity in catalase-deficient E. coli mutants and catalase plays an important role in protection of the cells against hydroquinone toxicity.     

A comparison of plants regenerated from a variegated <Emphasis Type="Italic">Epipremnum aureum</Emphasis>

In order to study chloroplast biogenesis, we chose natural variegated Epipremnum aureum (golden pothos) and regenerated pale yellow, variegated and green plants from all three types of tissue explants. The percentage of three types of regenerated shoots from three different explants was very close. Regenerated plants have been maintained for a year and show no sign of a colour switch. By comparing their protein profiles, two major differences between pale yellow and green plants were observed at the 15 and 40 to 50 kDa proteins. Moreover, pale yellow plants had unexpected high molecular mass proteins (greater than 60 kDa). Both variegated and green plants had more chlorophyll (Chl) a than Chl b, the ratios were about 1.46 and 1.93, respectively. In contrast, the pale yellow plants not only had less total Chl, but also the reduction of Chl a was much greater than Chl b, resulting in a higher content of Chl b than Chl a. Microscopic analysis revealed that pale yellow plants contained predominantly undeveloped chloroplasts with low Chl contents, even though their mesophyll cells were similar to green and variegated plants. PCR amplification of chloroplast DNA with 14 universal chloroplast primers did not reveal any difference among these regenerated plants.     

Universal chlorophyll equations for estimating chlorophylls <Emphasis Type="Italic">a,b, c</Emphasis>, and <Emphasis Type="Italic">d</Emphasis> and total chlorophylls in natural assemblages of photosynthetic organisms using acetone,methanol, or ethanol solvents

A universal set of equations for determining chlorophyll (Chl) a, accessory Chl b, c, and d, and total Chl have been developed for 90 % acetone, 100 % methanol, and ethanol solvents suitable for estimating Chl in extracts from natural assemblages of algae. The presence of phaeophytin (Ph) a not only interferes with estimates of Chl a but also with Chl b and c determinations. The universal algorithms can hence be misleading if used on natural collections containing large amounts of Ph. The methanol algorithms are severely affected by the presence of Ph and so are not recommended. The algorithms were tested on representative mixtures of Chls prepared from extracts of algae with known Chl composition. The limits of detection (and inherent error, ±95 % confidence limit) for all the Chl equations were less than 0.03 g m⁻³. The algorithms are both accurate and precise for Chl a and d but less accurate for Chl b and c. With caution the algorithms can be used to calculate a Chl profile of natural assemblages of algae. The relative error of measurements of Chls increases hyperbolically in diluted extracts. For safety reasons, efficient extraction of Chls and the convenience of being able to use polystyrene cuvettes, the algorithms for ethanol are recommended for routine assays of Chls in natural assemblages of aquatic plants.     

An Unbalanced Two-way Model With Random Effects Having Unequal Variances

Consider the model y_ijk=u ± a_i ± b_i ± c_ij ± e_ijk i=1, 2,…, t; j=1, 2,…b; k=1, 2,…,n_ij where μ is a constant and a_i, b_i, c_ij are distributed independently and normally with zero means and variances Δ₂ Δ2/bd_ij and δ₂ respectively. It is assumed that d_i's, and d_ij's are known (positive) constants (for all i and j). In this paper procedures for estimating the variance components (Δ₂, Δ²_b and Δ²_a) and for testing the hypothesis H_oc:Δ²_c/Δ² = y₃ and H_oa:Δ²_b/Δ² = y₄ (where y₂, y₃, and y₄, are specified constants) are presented. A generalization for the mixed model case is discussed in the last section.     

cDNA sequence of four purine nucleoside phosphorylase (Np) alleles in the mouse

The molecular basis of four electrophoretic and activity variants of purine nucleoside phosphorylase in the mouse was examined by amplification and sequence analysis of cDNA. Compared with the cDNA coding sequence for C3H/HeHa designated Np ^a , there were five nucleotide changes for C57BL/6J, Np ^b ; three for MOLF/Ei, Np ^c ; and five for SPRET-1, Np ^d . There was only a single codon change between Np ^a and Np ^b , the deduced substitution of threonine 176 by serine. Similarly, there was only a single codon change between Np ^a and Np ^c , resulting in substitution of methionine 258 by lysine. There were three codon changes between Np ^a and Np ^d , resulting in substitution of glutamate 22 by lysine, threonine 39 by alanine, and aspartate 152 by glutamate. These amino acid substitutions-neutral to neutral, neutral to basic, and acidic to basic—are in agreement with the electrophoretic properties of the gene products of Np ^a relative to Np ^b , Np ^c , and Np ^d previously described by isoelectric focusing. Codon differences were confirmed by PCRRFLP or single nucleotide primer extension analysis and extended to include the assignment of other strains as Np ^a : C3H/HeHa, DBA/2J, CLA, Posch-2; or Np ^b : C57BL/6J, C57L/J, C58/J. Both RFLP analysis of amplified genomic DNA and Southern analysis are consistent with single but unique Np alleles present in the C3H/HeHa and C57BL/6J genomes. As these data do not support the previous two-loci, Np-1 and Np-2, classification, we propose and employ a new single locus multiple allele classification for Np on the basis of the sequence analysis.     

Genetic fine structure and complementation at the albino locus in spider mites (Tetranychus species: Acarina)

Two mutations inTetranychus urticae and nine inTetranychus pacificus, all originating spontaneously, block the production of red and yellow carotenoid pigments in these spider mite species. Inter-mutant crosses were carried out to study complementation and recombination relationships between the mutations. InT. urticae, the two albino mutants complement one another completely, i.e., crosses between them produce wild-type hybrid females; while they recombine with a frequency of 0.05%. Of the nine mutants inT. pacificus, fivep mutants in general are complementary to a high degree with foura mutants.p mutants fail to complement one another, while somea mutants are mutually complementary to a slight degree. Scoring the degree of complementation produced by all possible combinations of mutants permits the construction of a linear complementation map. Certain combinations, however, are exceptional to such a representation. Moreover, marked reciprocal differences in complementation indicate that maternal effects are involved, implying that the albino locus may control more than one enzymatic step. Attempts to derive a genetic map were impeded by the absence of suitable linked markers, by a pronounced maternal effect (high pigmentation) in the haploid F₂ males, and by the appearance of pseudowild type F₂ males. The given genetic sequence, although comparable in a limited fashion to the complementation map, is considered tentative. Pink types appeared in crosses with certainp mutants. These were due to mutation at a separate locus, called rose, and seem to involve the production of pink pigments in an alternative or substitute pathway. A scheme attempting to orientate the present state of understanding of pigmentation in spider mites is presented.This work forms part of a thesis submitted in fulfillment of the requirements for the Ph. D. degree at the University of Amsterdam (1969).     

The developmental genetics of pigment mutants in the Mexican axolotl

The Mexican axolotl (Ambystoma mexicanum) provides a well-defined set of color genes which are useful for various types of analyses. These include the a (albino), m (melanoid), ax (axanthic), and d (white) genes. In addition, various combinations of these genes and a number of as yet undescribed mutants also exist. Three of these mutants (a, ax, and m) have defects associated with specific neural-crest-derived pigment cell types. The fourth mutant (d) appears to provide an unsuitable environment for the migration and maintenance of pigment cells. In one case (m), detailed information concerning the specific nature of the genetic defect is available. The goal of this article is to demonstrate ways in which the existing information on the axolotl color genes can best be utilized in terms of understanding not only the mutant phenotypes, but basic concepts in the cell and developmental biology of pigmentation as well. Thus, an attempt has been made to sort through the genetic and biochemical data relevant to these mutants in order to stimulate renewed interest in a more detailed pursuit of such studies.