The effect of the r a and r b loci on the lipid content of the seed of Pisum sativum

Summary The lipid content of seed from a set of isogenic lines for the R _a : r _a locus has been determined; the results show that this locus as well as affecting the starch, sugar and storage protein content and composition, also has a marked effect on the lipid content of the seed. Genotypes having different combinations of alleles at the r _a and r _b loci have also been examined; an r _a r _a r _b r _b , genotype had 5.57% purified total lipid in its seed — a more than 2-fold increase over that found in the round-seeded varieties (R _a R _a R _b R _b ) usually grown for the dry sed crop.     

Limiting similarity and the form of the competition coefficient

The question of whether there is a limit to the similarity of competing species has previously been investigated by a number of authors. These studies have all used the Lotka-Volterra model of competition, and have assumed that the competition coefficient α_ij may be calculated using the expression, α_ij = ∝ U_i(R) U_j(R) dR/∝ (U_i(R))² dR. In this paper, the generality of this formula is questioned and two alternative expressions for α_ij are proposed. When these expressions are used in an analysis of limiting similarity, qualitatively different conclusions emerge regarding the existence and nature of this limit, using either deterministic or stochastic models. The relevance of these findings to theories of character convergence and similarity barriers is discussed. The available field evidence does not strongly support the validity of the formula for α_ij used in previous studies. Since a given method of calculating α_ij must be derived from a higher level model, it is suggested that the Lotka-Volterra model is not sufficient in an investigation of limiting similarity.     

Non-Circadian Periodicity in the Duration of the Cell Cycle and the G1 Phase in the Hindlimb Epidermis of the Anuran Tadpole,Rana Pipiens

Using the percentage labeled mitoses method, seven cell cycle determinations were initiated at 6-hr intervals over a 36-hr span in order to see if the cell cycle in the tadpole hindlimb epidermis varied with time or showed rhythmicity. There was a pattern of two long cell cycles followed by a shorter one. Total cell cycle length (Tc) and the length of the G₁ phase plus one-half of the mitotic time (TG₁+½M) fluctuated the most, although only TG₁+½M varied significantly with the Chi-square test. The proportion of TC spent in each phase was also calculated. Only TG₁+½M/Tc had statistically significant fluctuations with time.

Rhythmicity was analyzed by a computer program using the method of least squares for cosine curve fitting. Statistically significant ultradian rhythms of 18.4 hr in TC, 18.5 hr in TG₁+½M and 18.6 hr in TG₁+½M/TC and the length of the DNA synthetic phase/total cell cycle length (TS/TC) were found. Circadian rhythmicity was not observed. The acrophases of the ultradian rhythms of TC and TG₁+½M coincided, suggesting that the rhythm of TC was due mainly to variation in TG₁+½M. In the absence of significant variation in TS, the longest phase of the cell cycle, whenever G₁+½M was short, TS/TC increased, so that the 18.6 hr rhythm in TS/TC was also a result of the periodicity in TG₁+½M.     

Optimal Fixing of the Bandwidth-Parameter for the Empirical Regression1,2

The estimator ?₀(x) of the regression r(x) = E (Y | × = x) from measured points (x_i, y_i), i = 1(1) n, of a continuous two-dimensional random variable (X, Y) with unknown continuous density function f(x, y) and with moments up to the second order can be made with the help of a density estimation f?₀(x, y) (see e.g. SCHMERLING and PEIL, 1980). Here f?₀(x, y) still contains free parameters (so-called band-width-parameters), the values of which have to be optimally fixed in the concrete case. This fixing can be done by using a modification of the maximum-likelihood principle including jackknife techniques. The parameter values can be also found from the estimators for r(x). Here the cross-validation principle can be applied. Some numerical aspects of these possibilities for optimally fixing the bandwidth-parameter are discussed by means of examples. If ?₀(x) is used as a smoothing operator for time series the optimal choice of the parameter values is dependent on the purpose of application of the smoothed time series. The fixing will then be done by considering the so-called filter-characteristic of ?C₀(x).     

Reconstruction of the last marine connectivity of the Zagros basin,based on fossil evidences of the clastic-dominated Bakhtiari Formation

In this study, new paleontology and lithology foundations on the Bakhtiari Formation were obtained from Shalamzar area in Zagros basin. A depositional mollasic cycle was divided into Bk1, Bk2 and Bk3 units from the base to the top of the Formation. Bk2, with limestone- and mudstone-dominated deposits, was found to alternate with conglomerates and form a marine succession between the two limestone clast-supported conglomeratic continental units. A diverse fossil association has been described for the first time and consists of foraminifera (Oolina spp., Oolina hexagona, Textularia spp., Spiroloculina spp., Peneroplis spp., Elphidium spp., Planulina sp., Amphistegina spp., Lagena spp. Globigerina spp., Globigerinoides spp., Uvigerina spp., Triloculina spp., Quinqueloculina spp., Spiroloculina spp. Nodosariid., Orbitina spp., Borelis melo, Bolivina spp. and Miogypsina spp.), a gastropod community of Strombus spp., Potamides spp., Turitella spp., Cyprea cf. persica and Pleurotomaria sp. and a higher energy colony of scleractinian corals comprising Porites branching, Porites-encrusting massive Favites spp., Favia spp., Tarbellastrea spp. and Acropora spp. The early–middle Miocene marine level of the Bakhtiari Formation, confirms a nearshore accommodation through a middle shelf and an open coastal lagoon (inner shelf) within a fluvial-dominated delta or open estuary during the last presence of a marine trough in the Zagros basin. This saline to hypersaline shallow marine regime was probably dominated in tropical to subtropical conditions. Palaeobiogeography analysis reflects a last seaway faunal exchange between the area and early–middle Miocene basins of Pakistan, India, Australia, Turkey, Greece, Romania Algeria, Egypt, Italy, France, Portugal and Austrian/Hungarian border, which reconstructs a shallow junction between Zagros basin and Mediterranean Tethys and Indo-pacific Ocean during Burdigalian–Langhian (Badenian) before the terminal Tethyan event in late middle Miocene and Tortonian.     

On the generalization of the logistic law of growth

This communication presents a discussion of some extensions of the formalism of Verhulst's simple logistics, which may constitute an autonomous growth model of a more general scope.For that purpose, the basis concept of growth diagram or trajectory is called upon, as it affords the graphic representation of the change in the growth variable y, using two relevant kinetic parameters: the instantaneous rate and the instantaneous acceleration. The two possible kinds of trajectories are in relation to the use of absolute (V = dyldt; = dV/dt) or relative (or specific) values (R = (1/y)(dy/dt); _R = dR/dt).In the case of simple logistics, the trajectory (V, ) allows 4 growth phases or states to be distinguished. The diagram (R, _R ) shows that the deceleration of the specific rate is not monotonous.In the case of Richards - Nelder's generalized logistics, the qualitative variation of the growth trajectory depends on the value of the dissymmetry parameter (occurrence of a critical value which determines the number of growth states).Blumberg's model is characterized by an analogous property and, moreover, can account for a non monotonous variation of the specific growth rate.     

Intra-H-2 recombination in the mouse

Serological characterization of threeK-S interval recombinant strains, TBR2 (H-2 ^at2 ), TBR3 (H-2 ^at3 ) and AIR1 (H-2 ^a2 ) was performed using anti-H-2, Ia, Ss and Slp antisera. The data presented here reveal that the crossover events in both TBR2 and TBR3 occurred between theI-A andI-E subregions. In both cases, theH-2K andI-A subregions were derived from theH-2 ^t1 chromosome, while theI-E, S andH-2D regions were derived from theH-2 ^b chromosome (K ^s A ^k E ^b S ^b D ^b ). TheH-2 ^a2 chromosome resulted from a crossover event between theH-2 ^a1 andH-2 ⁱ⁹ chromosomes. Ia and Ss typing of AIR1 suggested that theK toI-E regions originated fromH-2 ^a1 and theS andD regions originated fromH-2 ⁱ⁹ (K ^k A ^k E ^k S ^b D ^d ).     

Simulation of the dynamics in the Baker's yeast process

Simulation of the dynamics in a fed batch process for production of Baker's yeast is discussed and applied. Experimental evidences are presented for a model of the energy metabolism. The model involves the concept of a maximum respiratory capacity of the cell. If the sugar concentration is increased above a critical value, corresponding to a critical rate of glycolysis and a maximum rate of respiration, then all additional sugar consumed at higher sugar concentrations is converted into ethanol.In a fed batch process with constant sugar feed the sugar concentration declines slowly. If ethanol is present when the sugar concentration declines below the critical value of 110 mg/dm³ fructose +glucose the metabolism switches rapidly into combined oxidation of sugar and ethanol. Thus, no diauxic growth is involved under process conditions. The rate of ethanol consumption is determined by the free capacity of respiration under these conditions. The invertase activity of the cells was found to be so high that mainly fructose and glucose were present in the medium, typically in the concentration range around 100 mg/dm³. These components are consumed at the same rate but with fructose at a higher concentration, indicating a higher K _s for fructose consumption.The model was used in simulation experiments to demonstrate the dynamics of the Baker's yeast process and the influence of different process conditions.List of Symbols DOT % air sat dissolved oxygen tension - F dm³/h rate of inlet medium flow - H kg/(dm³ % air sat.) oxygen solubility - K kg/m³ saturation constant specified by index - K _L a 1/h volumetric oxygen transfer coefficient - m g/(g · h) maintenance coefficient specified by index - P kg/(m³ · h) mean productivity of biomass in the process - q g/(g · h) specific consumption or production rate - S kg/m³ concentration of sugar in reactor - S ₀ kg/m³ concentration of inlet medium sugar medium t h process time - V dm³ medium volume - X kg/m³ concentration of biomass - Y g/g yield coefficient specified by index - 1/h specific growth rate Index aa anaerobic condition - c critical value - e ethanol - ec ethanol consumption - ep ethanol production - max maximum value - o oxygen - oe oxygen for growth on ethanol - os oxygen for growth on sugar - s sugar - x biomass     

Phragmoplastins,the Trentepohliales,and the Evolution of the Cytokinesis in Green Plants

Representatives of the monophyletic Trentepohliales are widely distributed in the tropics, subtropics, and temperate regions worldwide. They grow in soil, or are epilithic, epiphytic or endophytic. The family comprises approximately 70 species placed in at least four genera (Trentepohlia, Cephaleuros, Phycopeltis and Stomatochroon), with Trentepohlia sensu lato (including Printzina and Physolinum) accounting for half of the species in this family. PCR amplification and sequencing of the 18 SSU rDNA of 18 isolates of the Trentepohliaceae were used to assess the monophyly of the genus Cephaleuros and to determine the phylogenetic relationships among species of Trentepohlia sensu lato. Distance, Parsimony, and Maximum Likelihood analyses indicate that Trentepohlia sensu lato is basal and includes two species recently transferred to Phycopeltis (P. umbrina) and Printzina (P. lagenifera). In contrast, Cephaleuros is a derived monophyletic clade. Analysis of isolates of C. virescens, from the USA, Taiwan, and South Africa indicate that this taxon may consist of different species sharing a convergent morphology. The results of this study have implications for the taxonomy of the genera.     

Supplement to the hepatic flora of the Shetland Islands

Background: Grasslands have only a few dominants and most of the diversity consists of subdominants. Because dominants differ widely in phenology and resource use, dominants may control the recruitment and establishment of other species.

Aims: To explore the relationship between the identity of the dominant species and successional vegetation changes in grassland communities.

Methods: The compositional change over 23 years in 1900 permanent plots dominated by four grasses (Andropogon gerardii, Elymus repens, Poa pratensis and Schizachyrium scoparium) was examined within 19 old fields in Minnesota. Fields were abandoned 1–56 years before sampling. Rate of directional change and degree of compositional dissimilarity were determined.

Results: Non-natives, P. pratensis and E. repens, were associated with either no or a slow directional change. Elymus repens was associated with high dissimilarity and P. pratensis with intermediate dissimilarity. Natives, A. gerardii and S. scoparium, were associated with compositional change that followed expectations based on field age. The rate of directional change and degree of dissimilarity between sampling intervals was lower for A. gerardii relative to S. scoparium, the only species to be associated with strong directional change.

Conclusions: Dominance by non-native grass species may impede traditional successional processes and result in a community composition quite dissimilar from native prairies.     

Unravelling the structure and function of the petal appendages in the tribe Schwenckieae (Solanaceae)

• The tribe Schwenckieae (Solanaceae) is characterised by the presence of appendages on the corolla, a diagnostic trait for the group. These appendages constitute a median distal projection of the three‐lobed petal and occur in the genera Melananthus and Schwenckia but are absent in Heteranthia.
• We investigated the micromorphology and anatomical structure of the appendages and lateral petal lobes of Schwenckia americana (two varieties), S. angustifolia, S. curviflora and S. novaveneciana, and Melananthus fasciculatus. We also performed histochemical tests to determine if the appendages are involved in the production of volatiles, acting as a fragrance secretory structure (osmophore).
• The appendages have a uniseriate epidermis, whose cells store phenolics and lipids. The parenchyma is starch‐rich just prior to anthesis in all species studied. The sensory test and anatomical analyses identified scent‐secreting tissues, not only in the appendages, but also in the lateral petal lobes, whose cells are papillose with a sculptured surface. The α‐naphthol p‐phenylenediamine (NADI) reaction detected volatile (essential oils) compounds in S. americana var. americana and S. americana var. angustifolia.
• We demonstrated the secretory tissues and the production of lipids in the corolla appendages of Schwenckia and Melananthus, which indicate their osmogenic function and probable scent emission to attract pollinators.

     

Updating the Taxonomy of Dermatophytes of the BCCM/IHEM Collection According to the New Standard: A Phylogenetic Approach

Recent taxonomical revisions based on multilocus gene sequencing have provided some clarifications to dermatophyte (Arthrodermataceae) family tree. These changes promoted us to investigate the impact of the changed nomenclature of the dermatophyte strains in the BCCM/IHEM fungal collection, which contains strains of all dermatophyte genera except for Ctenomyces. For 688 strains from this collection, both internal transcribed spacer region (ITS) and partial β-tubulin (BT) sequences were aligned and a multilocus phylogenetic tree was constructed. The ITS?+?BT phylogentic tree was able to distinguish the genera Arthroderma, Lophophyton, Microsporum, Paraphyton, Nannizzia and Trichophyton with high certainty. Epidermophyton, which is widely considered as a well-defined genus with E. floccosum as the only representative, fell within the Nannizzia clade, whereas the phylogenetic analysis, based on the ITS region alone, differentiates Epidermophyton from Nannizzia as a separate genus. Re-identification and reclassification of many strains in the collection have had a profound impact on the composition of the BCCM/IHEM dermatophyte collection. The biggest change is the decline of prevalence of Arthroderma strains; starting with 103 strains, only 22 strains remain in the genus after reassessment. Most Arthroderma strains were reclassified into Trichophyton, with A. benhamiae and A. vanbreuseghemii leaving the genus. The amount of Microsporum strains also dropped significantly with most of these strains being reclassified into the genera Paraphyton and Nannizzia.

     

The paracellular channel for water secretion in the upper segment of the Malpighian Tubule of Rhodnius prolixus

Lumen to bath J ₁₂/C ₁ and bath to lumen J ₂₁/ C ₂ fluxes per unit concentration of 19 probes with diameters (d ^m) ranging from 3.0–30.0 Å (water, urea, erythritol, mannitol, sucrose, raffinose and 13 dextrans with d ^m 9.1–30.0 Å) were measured during volume secretion (J _v ) in the upper segment of the Malpighian Tubule of Rhodnius by perfusing lumen and bath with ¹⁴C or ³H-labeled probes. J _net=(J ₁₂/C ₁ – J ₂₁/C ₂) was studied as a function of J _v · J _v was varied by using different concentrations of 5-hydroxy tryptamine. J _net for ³H-water was not different from J _v We found: (i) A strong correlation between J _net and J _v for 8 probes d ^m =3.0–11.8 Å (group a probes), indicating that the convective component of J _net is more important than its diffusive component and than unstirred layers effects which are negligible. Therefore group a probes are solvent dragged as they cross the epithelium, (ii) There is no correlation between J _net and J _v for 11 probes with d ^m=11.8–30 Å (group b). Therefore these probes must cross the epithelium by diffusion and not by solvent drag, (iii) In a plot of J _net/J _v vs. d ^m group a probes show a steep linear relation with a slope = –0.111, while for group b probes the slope is –0.002. Thus there is a break between groups a and b in this plot. We tried to fit the data with models for restricted diffusion and convention through cylindrical or parallel slit pathways. We conclude that (i) group a probes are dragged by water through an 11.0 Å-wide slit, (ii) Most of J _v must follow an extracellular noncytosolic pathway, (iii) Group b probes must diffuse through a 42 Å-wide slit, (iv) A cylindrical pathway does not fit the data.E.G. is a Visiting Scientist at IVIC. It is a pleasure to thank Drs. A.E. Hill and Bruria Shachar-Hill for their suggestion of the use of dextrans, their instruction and help with the dextran separation technique, and their extensive discussions. Dr. R. Apitz, Mr H. Rojas and Mrs. Fulvia Bartoli were most helpful with suggestions during the course of the experimental work. Mr. Jose Mora was fundamental help with the equipment. Mrs. Lelis Ochoa and Mr. Luis F. Alvarez helped with some of the drawings. This work was partially supported by CONICIT, Fundación Polar and CDCH of UCV. It is a pleasure to thank Dr. H. Passow and Dr. K.J. Ullrich at the Max Planck Institut für Biophysik (Frankfurt/Main) where this work was initiated.     

Diversity associated with the second expressed H L A - D R B locus in the human population

Although diversity within the HLA-DRB region is predominantly focused in the DRB1 gene, the second expressed DRB loci, DRB3, DRB4, and DRB5, also exhibit variation. Within DRB1 ^* 15 or DRB1 ^* 16 haplotypes, four new variants were identified: 1) two new DRB5 alleles, DRB5 ^* 0104 and DRB5 ^* 0204, 2) a haplotype carrying a DRB1 ^* 15 or ^* 16 allele without the usual accompanying DRB5 allele, and 3) a haplotype carrying a DRB5^* 0101 allele without a DRB1 ^* 15 or ^* 16 allele. The evolutionary origins of these haplotypes were postulated based on their associations with the DRB6 pseudogene. Within HLA haplotypes which carry DRB3, a new DRB3 ^* 0205 allele and one unusual DRB3 association were identified. Finally, two new null DRB4 alleles are described: DRB4 ^* 0201N, which exhibits a deletion in the second exon, and a second allele, DRB4 ^* null, which lacks the second exon completely. Gene conversion-like events and variation in the number of functional genes through reciprocal recombination and inactivation contribute to the diversity observed in the second expressed HLA-DRB loci. Received: 2 November 1996 / Revised: 23 December 1996     

Involvement of IS1 in the dissociation of the r-determinant and RTF components of the plasmid R100.1

Summary Detailed mapping localized the PHO 1 mutation between the OLI 2 and OLI 4 loci on mitochondrial DNA of Saccharomyces cerevisiae.In its mitochondrially integrated form, the PHO 1-ATPase³ was difficult to identify either immunologically or by specific inhibitors like oligomycin and DCCD. Solubilization by Triton X-100 allowed unambiguuous identification of this enzyme as an authentic mitochondrial ATPase. However, Triton extraction produced a 2 to 3 fold enhancement of the PHO 1-ATPase activity which also became drastically cold-sensitive. The wild type ATPase was neither activated nor made cold-labile by solubilization, and retained full sensitivity to oligomycin and DCCD.Sucrose gradient analysis of the Triton-extracted ATPase from wild type, PHO 1 mutant and rho ^- strains showed a density difference between the solubilized PHO 1-and wild type ATPase, and similarity between solubilized PHO 1-and rho ^- ATPase (F₁).Whole cells of the PHO 1 mutant present considerably increased respiration rates.Comparison of oligomycin-sensitivity in whole cells, coupled isolated mitochondria and membrane-bound ATPase indicates a contrast between oligomycin-resistance of the ATPase and oligomycin-sensitivity of in vivo or in vitro coupling systems, which might characterize the products of this region of mitochondrial DNA.     

Cloning of the Bz2 locus of Zea mays using the transposable element Ds as a gene tag

Summary The Bz2 locus of Zea mays has been cloned, utilizing the presence of the transposable element Dissociation (Ds) at the locus as a gene tag. The Ds element inserted in the bz2-m allele was identified among many members of the Ac/Ds family in a Southern blot analysis of a population segregating for bz2-m and Bz2. After cloning a DNA fragment from the bz2-m allele, sequences flanking the Ds insertion were shown to be Bz2-specific and were used to isolate a homologous fragment from a wild-type Bz2 line. The Ds insertion in the bz2-m allele was found to be a Ds2 element identical to the Ds insertion in adh1-2F11.     

Development of the pedicle in the articulate brachiopod Terebratalia transversa (Brachiopoda,Terebratulida)

Summary The development of the pedicle in the articulate brachiopod Terebratalia transversa has been examined by electron microscopy. The posterior half of the free-swimming larva comprises a non-ciliated pedicle lobe that contains the primordium of the juvenile pedicle at its distal end. During settlement at five to six days post-fertilization, the pedicle lobe secretes a sticky sheet that attaches the larva to the substratum. As metamorphosis proceeds, the epithelium in the posterior half of the pedicle lobe produces a thin overlying cuticle, and the pedicle primordium develops into a stalk-like anchoring organ. The juvenile pedicle protrudes through the gape that occurs between the posterior margins of the shell valves. A cup-like canopy, called the pedicle capsule, lines the posterior end of the shell and surrounds the newly formed pedicle. The core of the juvenile pedicle is filled with a solid mass of connective tissue. Numerous tonofibrils occur in the pedicle epithelium, and the overlying cuticle consists of amorphous material covered by a thin granular fringe. By one year post-metamorphosis, a body cavity develops anterior to the pedicle. Two pairs of adjustor muscles extend from the posterior end of the shell and traverse the cavity to insert in the pedicle. The connective tissue core of the pedicle in sub-adult specimens lacks muscle cells but contains numerous fibroblasts and collagen fibers. Three regions are recognizable in the connective tissue compartment of the adult pedicle: a subepithelial layer of non-fibrous connective tissue, a central fibrous zone, and a proximal mass of tissue that resembles cartilage.List of abbreviations as adhesive sheet - bc body cavity - bv brachial valve of shell - cf collagen fibrils - ct connective tissue - cu cuticle - di diductor muscle - ec epithelial cell - f fibroblast - fz fibrous zone - g gut - gc granular cell - gd gastric diverticulum - ht hinge tooth - ia interarea of pedicle valve - icl inner cuticular layer - lo lophophore - lu lumen of gut - m mesenchyme - ma mantle - ml mantle lobe - ocl outer cuticular layer - p periostracum - pc pedicle capsule - pce pedicle capsule epithelium - pcl pedicle collar of shell - pcn pedicle connectives - pd pedicle - pe pedicle epithelium - pl pedicle lobe - pv pedicle valve of shell - pzc proximal zone of cartilage-like tissue - s substratum - sel subepithelial layer - t tendon - tf tonofibril - vam ventral adjustor muscle     

Theoretical studies on the role of food exploitation for the competition of scaamble type

A model was made to clarify the basic processes of competition to occur among larvae by the exploitation as defined byBakker (1969). It was found that this model is applicable to the experimental results on the food exploitation among Droshophila larvae obtained byBakker (1961). In the model the preimaginal stage is divided into two periods;T_f which is the time that a group of larvae spends in exhausting the food after hatching, and T_s which is the duration of the starvation period after T_f.T_f and then W_l (larval body weight) just after the end of T_f are decided by F_s (amount of food supplied per larva at larval hatching) and F_c (amount of food consumed per larva).T_f affects on the onset of T_s as well as R_l (rate of decrease in the individual body weight during T_s).W_a (weight of emerging adults) is gotten by a subtraction of R_l from W_l just after the end of T_f,R_e is affected directly by these components of W_l and R_l. As a result, W_a and R_e are expressed by functions of F_s. This model confirmed that the food exploitation lead to the competition of scramble type. Finally it was suggested that there exist some strategies which prevent ill-effects owing to the food exploitation.