Plant Nucleases. II. Properties of Corn Ribonucleases I and II and Corn Nuclease I

Three enzymes with ribonuclease activity, one of which also had deoxyribonuclease activity, have been isolated and partially purified from corn seeds and seedlings. The purification of Ribonuclease I from mature seed was previously reported. This enzyme has a pH optimum near 5.0, is loosely adsorbed to carboxymethyl-cellulose, and has a molecular weight of 23,000, determined by gel filtration.

Ribonuclease II was isolated from the microsomes of corn roots, and was partially purified by gel filtration. It has a pH optimum plateau from 5.4 to 7.0, and molecular weight of 17,000.

Nuclease I hydrolyzes both RNA and DNA. It was isolated from the large particles of a corn root homogenate and was partially purified on a carboxymethyl-cellulose column. It has a pH optimum at 6.2 and a molecular weight of 31,000.

The relative activities of the 3 enzymes for deoxyribonuclease and at pH 5 and pH 6.2 for ribonuclease may be used to characterize them during purification operations. Assays on homogenates of corn roots, and especially of the root tips, suggested that a fourth enzyme, which possesses deoxyribonuclease activity, is also present.

     

Conformational Isomerizations of the Poly(dA-dT) and Poly(amino2dA-dT) Duplexes Involving the Unusual X-DNA Double Helix: A Fourth Derivative Spectrophotometric Study

Abstract

Fourth derivative spectrophotometry has been applied to monitor conformational isomerizations of polynucleotides for the first time. The transitions studied have been the B-A and A-X isomerizations of poly(dA-dT) and the B-X one of poly(amino²dA-dT). Parameters obtained from the fourth derivative spectra have been used to follow these conformational changes. The A form of poly(dA-dT) has been characterized by a new fourth derivative peak at 293.0 nm which can be associated to interstrand adenine-adenine interactions. Furthermore, some of the fourth derivative peaks in the long wavelength region (270–310 nm) can be related to stacking interactions present in the polynucleotide double helices. The tentative assignment of these peaks, particularly that at 299.0 nm in the derivative spectra of poly(amino²dA-dT), to n→π^* electronic transitions is discussed.     

Antrodia onychoides (Egel.) Ryv. specie nuova per l'Italia. II

Abstract

Antrodia onychoides (Egel.) Ryv., new to Italy and very rare species in Europe. II. - The paper is concerned with the first Italian collection of A. onychoides, a resupinate polypore. From the literature, this is the fourth European finding of Antrodia onychoides and follows the first collection, occurred in 1913 near Oslo, in Norway, the second in France and the third in Finland.

Macroscopically A. onychoides could be misdetermined as a Tyromyces however, on the basis of microscopical features, there is no doubt concerning its determination as a species of Antrodia genus.     

The genus Gottschelia Grolle (Jungermanniopsida,Lophoziaceae) in China,with a description of G. grollei,sp. nov.

Abstract

The genus Gottschelia Grolle is reported as new to mainland China, from Yunnan Province. Previously G. schizopleura (Spruce) Grolle was the only known Chinese species, reported from Taiwan. However, two further species have recently been found in the Gaoligong Shan range, Yunnan Province, G. patoniae Grolle, Schill & D.G. Long, previously known from the East Himalaya of Nepal and India (Sikkim) and G. grollei D.G. Long & Váňa, described here as a new species endemic to China, the fourth known species in the genus. The differences between the three Chinese species are enumerated with notes on distribution and ecology.     

Reproductive biology of the polychaete Kefersteinia cirrata Keferstein (Hesionidae). II. The gametogenic cycle and evidence for photoperiodic control of oogenesis

The gametogenic cycle of Kefersteinia cirrata (Polychaeta: Hesionidae) is described for a population in north-east England.

Gametogenesis begins in September with previtellogenic and prespermiogenic phases of gametogenesis accumulating until December. Vitellogenesis and spermiogenesis are initiated in January and gravid animals are present in May. Breeding with an unmodified behavioural epigamy takes place in June and July.

The effects of environmental temperature and day-length on oocyte growth rates have been determined. There is a synergism between the accelerating effects of long day-length and elevated temperature, the day-length effect being dominant.     

Secondo Contributo Alla Conoscenza Dello Sviluppo Embriologico del Genere Centaurea L. (Asteraceae). Centaurea Horrida Bad

Summary

The Author has studied the embryological development of Centaurea horrida Bad., pure pliocenic endemisms of Sardinia and has established that:

1°) the cromosomic number of the species is: 2n = 18.

2°) the genesis of microspores is of simultaneous type;

3°) The archesporium is constituted of one cell only seldom accompanied by a basal cell;

4°) the development of the female gamethophyte is of normal type;

5°) even showing cases of degenerated antipodal cells, the species has a marked tendency to the polyantipody, sometimes also characterized by a strong hypertrophy of its cells;

6°) in the species the contemporary germination of some megaspores in the same ovule is enough frequent;

7°) there are also some cases of coesistence of some gamethophytes in their different stages of development;

8°) the phenomenon of «multiple oospheres» and of «multiple synergidae» may happen;

9°) in some ovules, near the egg-apparatus, cells of two or four nuclei may be found.

For these last ascertainments (8° and 9°) the Author makes the hypothesis that it may be probably an anomalous prolification of micropylar nuclei, or asynchronous development, for delayed germination of some micropylar megaspores producing primary stages of gamethophyte.

Moreover the Author has the opportunity to bring into evidence:

10°) a case of ovular teratology represented by the extraovular development of an adult gamethophyte very similar to those previously found by the Author himself in Petasites fragrans;

11°) frequent cases of regretion of female sexuality, founding that about the 10% of the flowers examined were functionally male. The Author has fronted the possibility of the existence, in Asteraceae, also of the type of inflorescence where «flowers are all tubulated: the marginal ones neuter, the others or hermaphrodite or hermaphrodite and male».     

A re-evaluation of the species of Mesochaete Lindh. (Rhizogoniaceae).

Abstract

Mesochaete grandiretis Dix. is reduced to synonymy with M. taxiforme (Hampe) Watts & Whitel. and a comparison is made with M. undulata Lindb. which has much smaller cells and also differs in perigonial and perichaetial leaves and capsule shape.     

Functional response of different stages of Hippodamia variegata (Col.: Coccinellidae) to Diuraphis noxia (Hemiptera: Aphididae) on two wheat cultivars

As one of the most important natural enemies of aphids, lady beetles have been widely used for the control of pest aphids. Important to the efficiency of natural enemies is their functional response to varying prey densities. In this study, the functional response of Hippodamia variegata Goeze (Col.: Coccienllidae) to different densities of Diuraphis noxia Mordvilko was examined on two wheat cultivars with different resistance levels under laboratory conditions (25 ± 1°C, 65 ± 5% RH and 16:8 L:D photoperiod). Our results revealed that all stages of H. variegata exhibited a type II functional response, in that predation decreased with increasing prey density. Searching efficiency (a) and handling time (T_h) of third instar larvae on the Sardari cultivar were 0.0285/h and 0.0079 h, while for fourth instar larvae these values were 0.0561/h and 1 × 10^?8 h, for males these values were 0.0412/h and 0.0173 h and for females were 0.059/h and 0.0168 h. The corresponding values for the back cross cultivar for third instar larvae were 0.0475/h and 0.0782 h, for fourth instar larvae were 0.0753/h and 0.0529 h, for males were 0.045/h and 0.0060 h and for females were 0.0516/h and 0.0077 h. This study demonstrated that these wheat cultivars do not have a significant effect on the functional response parameters of H. variegata life stages, except for the searching efficiency of third instar larvae and the handling time of male adults. The possible application of this species against Russian wheat aphids in an integrated pest management programme is also discussed.     

Recherches sur le genre Peyssonnelia (Rhodophycées). III. Peyssonnelia crispata sp. nov.

Abstract

Studies on the genus Peyssonnelia (Rhodophyceae). III. Peyssonnelia crispata sp. nov. – A new specie of Peyssonnelia (P. crispata) is described from deep waters (44 to 45 m.) off the mediterranean coast of France.     

A new scorpion fossil from the Cretaceous amber of Myanmar (Burma). New phylogenetic implications

A fossil scorpion belonging to a new family, genus and species, Chaerilobuthus complexus gen. n., sp. n., is described from Cretaceous amber of Myanmar (Burma). This is the third species and the fourth scorpion specimen to have been found and described from Burmese amber. The new family seems quite distinct from the family Archaeobuthidae Lourenço, 2001 described from Cretaceous amber of Lebanon.     

Polline fossile di Aesculus aff. hippocastanum L. nel Bacino di Leffe (Pleistocene inferiore). Posizione sistematica e significato paleoecologico

Abstract

Fossil pollen of Aesculus aff. hippocastanum L. in the Leffe Basin (Early Pleistocene). Systematic position and palaeocology. A new pollen analysis has been undertaken in the lacustrine and palustrine deposits of Leffe (Northern Italy), in order to re-evaluate the flora, the vegetation dynamics and the climatic change at the southern margin of the Alps during the lowermost Pleistocene.

The present paper deals with the systematic position and the ecology of a fossil taxon of Aesculus discovered in the Leffe sediments. The taxonomical approach is based on a comparative investigation on the pollen morphology of all the present-living species and the fossil taxon from Leffe. Some diagnostic features of the apertures and the exine ornamentation allowed to distinguish some groups, almost coincident with the sections in which the genus is presently subdivided.

The pollen morphology of the taxa which belong to the sections living in temperate regions and in the subtropical-tropical SE-Asia (section Calothyrsus Koch) notably differ.

Among temperate groups, the Section Aesculus can be characterized by having the biggest projections on the colpus membrane. The fossil pollen from Leffe sediments can be related with this Section. Moreover, a comparison of the Japanese living species (A. turbinata Bl.), with the European one (A. hippocastanum L.), indicates that the fossil pollen grains from Leffe may be related to A. hippocastanum. This supports the hypothesis of a Neogene divergence of a pontic-european group inside the Section Aesculus in agreement with the macrofloral record of the Neogene in Europe. Afterwards the palaecology of the Leffe horse-chestnut is discussed. A comparison between fossil pollen spectra and the analogues in the modern vegetation (Colchide, Mesia, Caucasian region and Allegheny Mountains, U.S.A.) shows good relationships in the floral composition.

Finally, the extinction time of some elements of the Colchic-Hyrcanian flora in Italy during the Quaternary is discussed.     

The East Flanders Prospective Twin Survey (EFPTS).

The East Flanders Prospective Twin Survey (EFPTS) is a registry of multiple births in the province of East-Flanders, Belgium. It has several unique features: it is population-based and prospective, with the possibility of long-term follow-up; the twins (and higher order multiple births) are ascertained at birth; basic perinatal data are recorded; chorion type and zygosity are established; and since 1969 placental biopsies have been taken and frozen at -20 degrees C for later determination of genetic markers. The EFPTS is the only large register that includes placental data and allows differentiation of three subtypes of monozygotic (MZ) twins based on the time of the initial zygotic division: the dichorionic-diamnionic pairs (early, before the fourth day after fertilisation), the monochorionic-diamnionic pairs (intermediate, between the fourth and the seventh day post fertilisation), and the monochorionic-monoamnionic pairs (late, after the eight day post fertilisation). This added a new dimension to didymology (the science of twins; delta iota delta upsilon mu omicron zeta = twins): the timing of twinning. Studies can be initiated on primary biases, those originating "in utero". Such studies may throw new light on the controversy over the validity of the classic twin method, the consequences of early embryological events (before and just after implantation of the embryo), the origin of congenital malformations, the sex proportion of multiples, the gene-environment interactions as far as intrauterine environment is concerned, to name but a few.     

Quantitative approaches to detect the fourth stage of the epidemiologic transition

Abstract

Widely diverse quantitative measures have been used to study the onset of the different stages of the epidemiologic transition, including the fourth stage. This report suggests additional methods for detecting the fourth stage of the epidemiologic transition that are more parsimonious than those previously used. While these methods are not new, they have potential for application in this area of research. An example of one of these methods is illustrated, using Canadian data.     

Effect of sediment elutriate on the growth of Gymnodinium sp. (Dinophyceae). I.

Abstract

Sediments from the Emilia Romagna coast, an area periodically subjected to eutrophication, were investigated to determine the organic carbon and nitrogen content from the solid phase and organic and inorganic phosphorus, nitrogen and N/P ratio from a liquid elutriate from these sediments. The elutriates were tested for growth using a bioassay with a Gymnodinium sp. which previously caused extensive blooms in the Adriatic. Cultures were grown in the elutriates either enriched or unenriched with F/2 medium. Comparisons with controls were made on the basis of the maximum standing stock. The results obtained with the unenriched elutriates demonstrated the primary role of phosphate, while enriched elutriates produced slighter enhancement than the control. In most cases, the chemical composition of the elutriate was characterized by a negligible phosphate concentration, with respect to ammonium: the nutrient balance did not agree with the nutritional algal requirement. However, all the elutriates showed large quantities of inorganic and organic nitrogen. This finding could indicate that sediment-bound nitrogen may be a ready source of nitrogen for algal growth.     

Genome-wide identification of conserved microRNA and their response to drought stress in Dongxiang wild rice (Oryza rufipogon Griff.)

Objectives

To identify drought stress-responsive conserved microRNA (miRNA) from Dongxiang wild rice (Oryza rufipogon Griff., DXWR) on a genome-wide scale, high-throughput sequencing technology was used to sequence libraries of DXWR samples, treated with and without drought stress.

Results

505 conserved miRNAs corresponding to 215 families were identified. 17 were significantly down-regulated and 16 were up-regulated under drought stress. Stem-loop qRT-PCR revealed the same expression patterns as high-throughput sequencing, suggesting the accuracy of the sequencing result was high. Potential target genes of the drought-responsive miRNA were predicted to be involved in diverse biological processes. Furthermore, 16 miRNA families were first identified to be involved in drought stress response from plants.

Conclusion

These results present a comprehensive view of the conserved miRNA and their expression patterns under drought stress for DXWR, which will provide valuable information and sequence resources for future basis studies.

     

Pattern formation in the wing veins of the fused mutant (Drosophila melanogaster).

In order to analyze the effects of the mutation fused (fu) on vein pattern formation, wings mosaic for fused and non-fused tissue were obtained. Analysis of these wings (1) confirmed that fused does not involve the production of a freely diffusible substance; (2) showed that a genotypically fu fourth longitudinal vein (LV 4) develops a normal phenotype nonautonomously if the third longitudinal vein (LV 3) and most of the first posterior cell are non-fused; (3) showed that in the reciprocal situation, a non-fused fourth longitudinal vein often exhibited autonomous differentiation; (4) demonstrated that small groups of cells (either fu or non-fu) could be incorporated into structures characteristic of the opposite genotype; and (5) offered evidence that the dorsal wing surface may play an important role in the control of vein formation. Additionally, the fused phenotype itself was examined in some detail, and the anterior-posterior compartment border was defined. This examination suggests that in the more extreme cases LV 4 does not fuse with LV 3, but simply fails to form.     

Extracts of the Brown Alga Dictyota dichotoma (Hudson) J.V. Lamouroux Alleviate Salt Stress in Rice (Oryza sativa L.) During Germination

Algal extracts provide a safe regime for enhancing crop productivity under stressful conditions. The present study evaluated the efficiency of aqueous and ethanolic extracts of the brown alga Dictyota dichotoma in alleviation of salt stress on germination of rice seeds. Firstly, seeds were germinated using the aqueous extract of D. dichotoma at concentrations of 0, 5, 10, 20, and 50 g L⁻¹, prepared either at room temperature (RTE) or by boiling (BLE). The % germination of rice increased from 84% in non-treated seeds to 100% when treated with 20 g L⁻¹ BLE, although this treatment caused reduced uniformity of germination. Embryo growth was maximum at 20 g L⁻¹ of both extracts with superiority of BLE over RTE. In the second experiment, the effect of 20 g L⁻¹ aqueous and ethanolic extracts relative to a balanced nutrient supply on germination of seeds treated with 0, 40, 90, and 170 mM NaCl was investigated. Salinity reduced % germination with delayed onset but high uniformity of germination, whereas algal amendments counterbalanced the effect of salinity to a greater extent relative to the nutrient supply. Upon withdrawal of salt stress, seeds promptly recovered, with more efficient recovery of seeds exposed to 170 mM than from 90 mM NaCl. The lower recovery of salt-treated seeds compared with the control seed germination suggests that rice suffered from the toxic ion effect of salinity on embryo rather than from the osmotic effect. Extracts of D. dichotoma can enhance and also alleviate salinity stress on rice seed germination.

     

Impact of different shade coffee management scenarios,on a population of Oncidium poikilostalix (Orchidaceae), in Soconusco,Chiapas, Mexico

Background: Understanding the effect of perturbation, be it natural or anthropogenic, on the demography and dynamics of the plant populations can help conservation management planning.

Aims: We assessed the impacts of management of a shade coffee plantation on a population of Oncidium poikilostalix (Orchidaceae).

Methods: We studied in a coffee (Coffea arabica) agroecosystem the impact of the current traditional management [T] and two hypothetical epiphyte control management scenarios (intense ‘desmusgue’ [ID] and moderate ‘desmusgue’ [MD]), on the only known Mexican population of O. poikilostalix. Based on 3 years of field demographics data, the population dynamics of the orchid were projected using T, ID and MD scenarios for 20 years into the future.

Results: Under the current management T, the population of O. poikilostalix was projected to grow continuously (λ = 1.102). Conversely, under management ID, the loss of individuals would lead to a sustained population decline (λ = 0.843); in the case of MD, the population would decline more slowly with the population growth rate tending towards equilibrium (λ = 0.966).

Conclusions: The changes in the management of coffee plantations that have become common throughout the south-east of Mexico represent a threat to the survival of the only population of O. poikilostalix in Mexico, and likely threaten other epiphytic species.