bluuebunny/crossref_metadata_2025_split huggingface dataset:
The boreal dwarf shrub Vaccinium vitis-idaea retains its capacity for photosynthesis through the winter
Authors: Lundell Robin , Saarinen Timo , Åström Helena , Hänninen Heikki 
Published: April 2011

The ability to retain their photosynthetic capacity through the winter may be important for plants in boreal conditions, where the growing season is relatively short and winter temperatures fluctuate from severe freezing up to near 0 °C. The snow cover is an important protector for field-layer plants against both extreme freezing and excessive light, both of which could damage the photosynthetic apparatus. To understand the importance of wintertime photosynthetic activity for evergreen boreal dwarf shrubs, the photosynthesis of Vaccinium vitis-idaea L. was monitored in field conditions for one year. A dynamic model was used to determine the relative effect of temperature on the photosynthetic capacity. Our results show that V. vitis-idaea retains its photosynthetic capacity throughout the winter: its average photosynthetic capacity in winter was almost 25% of the yearly maximum measured. Changes in photosynthetic capacity over the year reflect the changes in air temperature with a certain delay, except in summer. Concentrations of soluble sugars remained high during the winter months, probably as a consequence of CO2 uptake under the snow cover. Our measurements indicated no significant damage to the leaf tissue over the winter, but suggest that photoinhibition may occur immediately after snowmelt.
Variability of nitrogen-fixing Frankia on Alnus species
Authors: Markham John H. 
Published: April 2011

Plants maintain mutualistic symbioses with multiple symbiont genotypes that differ in the benefits they provide. To investigate differences in the effect of nitrogen-fixing Frankia on Alnus species, spore-producing (sp+) nodules from Alnus rubra Bong. and Alnus incana subsp. rugosa (Du Roi) Clausen and non-spore-producing (sp–) nodules from Alnus viridis subsp. crispa (Ait.) Turrill, A. rubra, and A. incana subsp. rugosa were collected from each of four different populations and used to inoculate all three Alnus species. As expected, sp+ Frankia produced significantly more nodules on all three species. However, A. crispa, which normally does not have sp+ nodules in the field, was more susceptible to a high level of infection by sp+ Frankia in general, and by any source of sp+ Frankia in particular, whereas A. incana subsp. rugosa, which has the highest abundance of sp+ in the field, was less susceptible to high levels of infection. This suggests that A. incana subsp. rugosa develops resistance to high levels of infection. The infectivity of an sp+ Frankia source on A. viridis subsp. crispa and A. rubra was positively correlated with the proportion of sp+ nodules on the site it was collected from, suggesting that the variation in the abundance of sp+ in the field is caused by sp+ Frankia with different levels of infectivity. There was no effect of Frankia sources on nodule allocation. Plant growth was positively correlated with the specific nodule mass and the specific nodule activity, and negatively correlated with the nodule number per plant. Sp+ Frankia resulted in significantly smaller plants in A. rubra. While there was no overall sp+ type effect on the growth of A. viridis subsp. crispa, the largest plants always resulted when they were inoculated with sp–, and the smallest with sp+ Frankia. Neither spore type nor inoculum source had any effect on the performance of A. rugosa. These results suggest that Alnus species remain susceptible to infection by both Frankia spore types, but are able to modulate the effectiveness of these spore types when they are the common symbionts in the field.
Morphological studies of developingRubusprickles suggest that they are modified glandular trichomes
Authors: Kellogg Allicia A. , Branaman Tatum J. , Jones Nathan M. , Little Coleman Z. , Swanson John-David 
Published: April 2011

Prickles are defined as outgrowths of epidermal tissues and can provide a simple developmental system for the study of the control of cell proliferation and growth. Setting the stage for future studies on gene regulation in the genus Rubus (brambles), a detailed analysis and staging series of prickle development in Rubus idaeus subsp. idaeus L. (red raspberry) is presented and compared with Rubus L. subsp. rubus Watson (blackberry) and Rosa hybrida L. 'Radtko' (rose). Morphological measurements from light and scanning electron micrographs were used to subdivide prickle development into four stages. Our studies indicate that raspberry and rose prickles are modified glandular trichomes continuing to grow and eventually hardening into their final prickle morphologies as outgrowths of epidermal tissue. Although glandular trichomes seem to be involved in blackberry prickle development, our studies indicate that these prickles do not follow the same developmental progression as raspberry, suggesting a potential evolutionary deviation from what is commonly seen in raspberry and rose.
Comparative leaf anatomy of four species of Bromelioideae (Bromeliaceae) occurring in the Atlantic Forest, Brazil
Authors: Pereira Tiago Augusto Rodrigues , de Oliveira Tuane Santos , da Silva Luzimar Campos , Azevedo Aristéa Alves 
Published: April 2011

Bromeliaceae, comprising 3172 species, is one of the most important families of the Brazilian Atlantic Forest owing to its high degree of endemism and occurrence in different habitats. The subfamily Bromelioideae is the most representative of Bromeliaceae and the best represented in the state of Minas Gerais, Brazil, with 120 species. The objective of this study is to compare the leaf anatomy of four species found in two areas of the Atlantic Forest: Serra do Brigadeiro State Park, Minas Gerais, Brazil ( Quesnelia strobilispica Wawra and Wittrockia gigantea (Baker) Leme) and a forest fragment located within Bom Sucesso Farm, Viçosa, Minas Gerais, Brazil ( Billbergia euphemiae E. Morren and Bromelia antiacantha Bertol.), relating environmental characteristics to the habit. Leaf samples were studied using light and scanning electron microscopy and histochemical tests with Sudan, phloroglucinol, and ruthenium red stains. Leaves of B. euphemiae and W. gigantea showed several adaptations to the epiphytic habit, including scales on both surfaces, thickened epidermal cell walls, presence of silica bodies, hypodermis with sclerified cells, water-storing tissue (hydrenchyma), and air channels formed by stellate cells in the chlorenchyma. The epiphytic species B. euphemiae and the terrestrial species Q. strobilispica have similar overall structure, including a well-developed parenchyma and extravascular fiber groups. Leaves of the terrestrial species Bromelia antiacantha and the epiphytic species W. gigantea also show structural similarities, such as lack of extravascular fibers and less developed parenchyma. Similar characteristics in species from different habitats may either reflect microclimatic conditions under which these species occur or genetically fixed characteristics.
The Life History and Post Embryonic Development of the Copepods, Calanus tonsus Brady and Euchaeta japonica Marukawa
Authors: Campbell Mildred H. 
Published: April 2011

Calanus tonsus Brady is an abundant, deep water species in the strait of Georgia. Development is characterized by a distinct metamorphosis and the six nauplius and six copepodid stages are described. The life cycle extends over one year and breeding occurs in the spring at the surface. The nauplii and early copepodid stages are soon replaced by stage V which dominates the plankton from May to December. C. tonsus exists as an adult for approximately two months—January and February. Maturity is accompanied by marked degeneration of the mouth parts in both sexes, death following shortly. The retrograde development appears associated with a change in habits. Stage V stores up reserve food, and the mature females with the disappearance of feeding devices depend upon this accumulated food during the reproductive period. Euchaeta japonica Marukawa occurs in limited numbers in the deep water of the strait of Georgia. It undergoes a similar metamorphosis to C. tonsus and the twelve stages are described. There is no definite spawning period but reproduction occurs throughout the year in deep water where development proceeds. Several broods may be produced by one female but the males are believed to die shortly after copulation. The nauplii differ from those of C. tonsus due to larger size, slight increase in length from stage I to stage VI and retarded development of the appendages. The conspicuous feature of the copepodid development is the extreme degeneration of the male mouth parts.
Effect of Temperature on the Cell Length and Shape of Bacillus vulgatus
Authors: Hess Ernest 
Published: April 2011

B. vulgatus cells, when growing at 37° and 20 °C. on agar-slants showed rapid initial temporary increase in mean length, while at 5° the increase was gradual and prolonged, with formation of very elongated cells. At 5°, where neither spore formation nor heat destruction of the cells interfered, as occurred at 20° and 37° respectively, maximum opportunity for modification of cell shape was given. Comparisons with data obtained on the growth rate of B. vulgatus at these temperatures indicate that increase in cell length occurred mainly during periods of low growth rate.
The Nutritive Value of Marine Products: VIII. Proximate Analysis of Canned British Columbia Sockeye and Pink Salmon
Authors: Carter Neal M. 
Published: April 2011

The proximate compositions and calculated calorific values of individual and composite samples of canned sockeye (Oncorhynchus nerka) and pink (O. gorbuscha) salmon from fish caught in several localities on the British Columbia coast are compared. The resulting data are also presented in such a way as to allow comparison of the composition and energy content of the various constituents in the can, some of which are frequently discarded in the utilization of canned salmon. The average percentages of the total oil, protein, salt (sodium chloride)-free minerals, and Calories contributed by the different constituents in the samples were respectively: flesh—(sockeye) 62, (pink) 72; 85, 81; 55, 54; 73, 78; skin—(sockeye) 11.2, (pink) 15.3; 3.6, 4.3; 9.8, 6.7; 7.7, 9.0; free aqueous liquor—(sockeye) 0, (pink) 0; 11, 14; 5, 7; 4, 8; free oil—(oil) 26, 10; (Calories) 15, 4; bone—(salt-free minerals) 30.2, 32.6. Corresponding average percentage compositions of composite samples of entire contents were: water—(sockeye) 68.6, (pink) 71.5; oil—8.82, 6.75; protein—20.2, 19.3; salt-free minerals—1.57, 1.57. The average energy contents were (sockeye) 749, (pink) 644 Calories per pound. Comparison with published analyses of canned sockeye and pink salmon from Alaska and Washington indicated that more extensive and detailed sampling will be necessary before conclusions can be drawn regarding the comparative compositions and food values of canned British Columbia salmons, and the relation of these values to those of salmon caught to the north and south.
The Measurement of Spoilage in Fish
Authors: Beatty S. A. , Gibbons N. E. 
Published: April 2011

The increase in volatile nitrogenous bases in codfish muscle between the pre-rigor period and the first appearance of odour is approximately 6 mg. per 100 grams of tissue, and is due almost entirely to the action of bacteria. It can be used to follow the course of spoilage only if the original value of the fish in question is known, as the range in variation of the original values is as great as the increase to the appearance of odour. A method for the rapid determination of "trimethylamine" in cod muscle has been devised. Its increase parallels the increase in bacterial population. Odours always appear at approximately the same level of "trimethylamine". The increase resulting from autolysis is negligible. The increase during the development of spoilage is fifteen to twenty times the original value. Spoilage can be followed in fish preserved with borates as well as in untreated fish.
The Biology of the Zooplankton Population in the Bay of Fundy and Gulf of Maine with Special Reference to Production and Distribution.
Authors: Fish Charles J. , Johnson Martin W. 
Published: April 2011

Analyses in the gulf of Maine and bay of Fundy show the zooplankton population to be dominated by a relatively few species of boreal endemic crustaceans. Calanus finmarchicus, the most abundant form, averaged 39.9 per cent by number in the total region during the period, April to September in 1932, and 35.5 per cent for the year in the bay of Fundy. Fluctuations in the volume of zooplankton reflect to a large extent numerical changes in the stock of this species. The vernal rise in 1932 occurred following propagation of Calanus, and the rapid downward trend in June coincided with the critical period of maturation and subsequent mortality of adults after spawning. Due to differences in the time of spawning in different parts of the region, two, and in some cases three, breeding stocks of boreal plankton animals can usually be distinguished. The distinct spawning periods are continued in subsequent generations that year no matter where distributed. Productivity was found to be closely correlated with temperature and stability of the water mass, and dispersal with the nontidal circulation in the region. The vernal crop of boreal plankton species appears to be derived largely from adults maturing in the western or outer gulf. With the advance of the season the centre of production moves to the eastern basin. The turbulent New Brunswick-eastern Maine coastal zone as far west as Mount Desert is relatively unproductive, and characterized by small zooplankton volumes.
Chromosomal distribution of genes in diploid Elytrigia elongata that promote or suppress pairing of wheat homoeologous chromosomes
Authors: Dvořák Jan 
Published: April 2011

Triticum aestivum L. lines with added or substituted chromosomes of Elytrigia elongata (Host) Nevski were hybridized with Hordeum bulbosum L. to obtain haploids and with Triticum urartu Thum. to obtain interspecific hybrids. Chromosome pairing at metaphase I was investigated in the resulting haploids and hybrids and the parental addition and substitution lines. Genes that promoted pairing of homologous or homoeologous chromosomes were found on chromosome arms 3ES, 3EL, 4ES, 5Ep, and chromosome 6E of E. elongata. Genes that suppressed pairing of homoeologous chromosomes were found on chromosome arms 4EL and 7Eq. It is concluded that genes promoting or suppressing pairing of homoeologous chromosomes are ubiquitous among diploid species. Key words: wheat, Triticum, wheatgrass, Elytrigia elongata, heterogenetic pairing, chromosome pairing, pairing promotion, pairing suppression.
Persisting demibivalents: a unique meiotic behaviour in Cuscuta babylonica Choisy
Authors: Pazy Batia , Plitmann Uzi 
Published: April 2011

Idiosyncratic chromosome behaviour during meiosis was found in pollen mother cells of Cuscuta babylonica Choisy, a thread-like holoparasitic herb. Its main features are among the following: (i) telomeric association between homologues through most stages of the process, which leads to persisting chromatid bivalents (= "demibivalents"); (ii) uncommon chromosome segregation in first and second anaphase; and (iii) prolonged intensified heterochromatinization. Although "regular" in its own way, this process leads to the formation of unviable products. Its further investigation might contribute to our understanding of the role of the spindle and chromosome movement in the ordinary process of meiosis. Key words: meiosis (abnormal), persisting demibivalents, Cuscuta babylonica.
Undifferentiated sex chromosomes in Mastotermes darwiniensis Froggatt (Isoptera; Mastotermitidae) and the evolution of eusociality in termites
Authors: Bedo D. G. 
Published: April 2011

Meiosis and mitosis was studied in males of the primitive termite Mastotermes darwiniensis, which is closely related to the Dictyoptera. In mitotic metaphase cells 98 chromosomes were found with a matching 49 bivalents at metaphase I. Mastotermes darwiniensis has a largely acrocentric karyotype with no sex-linked translocation complexes, like those found in many other termite species, or other sex chromosome differentiation. These observations suggest that ancestral termites probably had karyotypes with many small chromosomes lacking sex chromosome differentiation and that there is no connection between the evolution of sex-linked translocation complexes and eusociality. Key words: sex chromosomes, Mastotermes, termites, eusociality.
Diploid perennial intergeneric hybrids in the tribe Triticeae. III. Hybrids among Secale montanum, Pseudoroegneria spicata, and Agropyron mongolicum
Authors: Wang Richard R.-C. 
Published: April 2011

Four new intergeneric diploid hybrids were synthesized in the greenhouse with the aid of embryo culture. Hybrids of Pseudoroegneria spicata × Secale montanum and P. spicata ssp. inermis × S. montanum, both having the genome formula SR, averaged 12.97 I + 0.49 II + 0.01 III at metaphase I. The hybrids of Agropyron mongolicum × S. montanum, which have the PR genomes, had an average of 12.86 I + 0.51 II + 0.03 III + 0.004 IV. The hybrid (SP) between P. spicata ssp. inermis and Agropyron mongolicum had a mean configuration of 8.05 I + 2.86 II + 0.07 III + 0.01 IV. All hybrids had intermediate spike morphology, respective to their parents, and were sterile. Mitotic preparations of root-tip cells of these hybrids suggested that the chromosomes of different genomes were spatially separated. The meiotic pairings of these hybrids indicated that chromosome homology between the S and P genomes is higher than either the S and R or the P and R. Both SR and PR hybrids represent new genomic combinations. The SP hybrid is equivalent to the dihaploid of P. tauri. All of these hybrids should be of value for breeding and taxonomy. Key words: intergeneric hybrids, genome, Secale, Pseudoroegneria, Agropyron.
Cytogenetic studies of aneuploids in rapeseed. II. Morphology, fertility, and cytology of self-pollinated progenies of monosomic plants of Brassica napus L.
Authors: Chang Ru-ying , Tai William , Fan Z. 
Published: April 2011

Cytogenic studies were conducted on self-pollinated progenies from two monosomic lines of Brassica napus to ascertain the mode of transmission of the monosomic chromosome. An approximately 1:1 ratio of disomic to monosomic plants was obtained. Only one nullisomic plant was found among a total of 71 plants analyzed. The 1:1 ratio and the anaphase I disjunction (19–18) suggest that the gametes (n) were twice as competitive or functional as their counterpart (n − 1). Since quadrivalents were observed in the disomic plants and only trivalents in the monosomics, the monosomic chromosomes were believed to be the ones that were involved in the formation of multivalents. The percentage of multivalent association in monosomic plants was almost double that in disomic plants. In the disomic plants, an average of 11.96% of pollen mother cells had one to two quadri-valents. The average frequency of trivalents in the monosomics was 23.63%. It was suggested that pairing of these homologs was genetically controlled with a dosage effect. The absence of one chromosome increased the frequency of multivalents. Key words: monosomic, Brassica, rapeseed, aneuploid.
Crown rust resistance in progeny from a derived tetraploid × natural tetraploid cross in Avena
Authors: Karow R. S. , McNamara K. R. , Forsberg R. A. 
Published: April 2011

The F1 plants and F2 and F3 populations obtained from a cross between the derived oat tetraploid C.I.7232 and natural tetraploid oat Avena barbata Pott. var. Excoimbra Se1.20 were evaluated for reaction to crown rust. The adult F2 plants exhibited a hypersensitive crown rust resistance reaction and were intermediate to their parents in other characteristics. The F2 and F3 seedling and adult plant populations differed in their response to the same mixture of crown rust races, i.e., a two gene segregation ratio at the seedling stage but only one gene segregation in adult plant tests. The resistance of Se1.20 was found to be a type of "stage" resistance that was effective only in vegetative (seedling) growth stages. The resistance gene of Se1.20 could not be detected in progenies that were rust tested as adult plants. Key words: Puccinia coronata, Avena, derived tetraploid.
Inheritance of isozymes in seed and bud tissues of blue and Engelmann spruce
Authors: Ernst S. G. , Keathley D. E. , Hanover J. W. 
Published: April 2011

Thirteen loci from 11 enzyme systems were identified among full-sib and half-sib progeny of blue and Engelmann spruce. Eleven of the loci were expressed in bud, embryo, and megagametophyte tissue; the remaining two loci were expressed only in embryo and megagametophyte tissue. There were no mobility differences observed between loci expressed in seed and bud tissues. The mode of inheritance for 10 of the loci was confirmed based on progeny genotypic distributions. For the two loci not expressed in bud tissue, acid phosphatase (Acp-2) and diaphorase (Dia-2), inheritance was inferred from pooled segregation ratios of megagametophytes from open-pollinated seed from heterozygous females. The inheritance of glutamate oxaloacetate transaminase (Got-3) was also inferred from segregation ratios and diploid embryo phenotypes of open-pollinated progeny owing to a lack of variability at this locus among the 40 parents in the mating design. Two loci, aldolase (Ald) and malate dehydrogenase (Mdh-2), were monomorphic among the 20 parents of both species. Key words: isozymes, Engelmann spruce, blue spruce, Picea.
Digenomic triploids for an assessment of chromosome relationships in the cultivated diploid Brassica species
Authors: Attia T. , Busso C. , Röbbelen G. 
Published: April 2011

To assess the chromosomal relationships in the cultivated diploid Brassica species, four digenomic triploid combinations were synthesized and meiotically analyzed. Two of the four digenomic combinations contained the B genome of B. nigra, one with two (BC.B) and the other with only one B genome (C.BC). In these combinations preferential pairing between the two homologous genomes with the third single genome was predominant. Since gene actions suppressing pairing between chromosomes of related genomes had not been proven to exist in Brassica, this phenomenon is assumed to be conditioned by structural chromosomal differences reflecting the distant phylogenetic relationship of B. nigra to each of B. oleracea (CC) and B. campestris (AA). On the other hand, two other digenomic triploids having two A genomes and one C genome showed a low preferential pairing of the two homologous A genomes (to form 10 II + 9 I). Moreover, a high tendency for an allosyndetic pairing between the A and C genomes was expressed by the formation of one or more trivalents in over 50% of PMCs in the two combinations A.AC and AC.A. This demonstrated a high meiotic pairing potential and a small evolutionary difference between the chromosomes of B. campestris (AA) and B. oleracea (CC). Key words: Brassica, triploid (digenomic), phylogenetics, pairing (chromosome).
Sexual isolation between Drosophila melanogaster females and D. simulans males. II. Influence of female receptivity on hybridization
Authors: Carracedo Maria C. , Casares P. , Miguel E. San 
Published: April 2011

Hybridization between Drosophila melanogaster females and D. simulans males was measured in sympatric and allopatric populations of these sibling species by means of nonchoice tests. Greater sexual isolation was found in allopatric populations over sympatric ones. Notable age differences at which females reached sexual maturity were detected in the D. melanogaster populations. Females with an earlier sexual maturity also showed greater receptivity. Remarkably, female receptivity was the main factor accounting for frequency of hybridization. The role that both male and female mate propensities and discrimination abilities play in natural selection for sexual isolation is discussed. Key words: sexual isolation, Drosophila, female receptivity, hybridization.