Miracle-dz/UniFAR-FTUs huggingface dataset:
The population biology of two species of eyefluke, Diplostomum spathaceum and Tylodelphys clavata, in roach and rudd

Infections of roach (Rutilis rutilus), and rudd (Scardinius erythrophthalmus), by the eyeflukes Diplostomun spathaceum and Tylodelphys clavata were studied in a lake over a three year period. T. clavata first appeared at the beginning of the study. Roach were heavily infected by both parasites, whereas the rudd contained very few specimens of either species. A small number of roach-rudd hybrids were also examined, and appeared to have a susceptibility intermediate between the parental types. Levels of T. clavata in roach increased throughout the study. This parasite had a life span of a year or less in the fish, and was continuously lost from the population. This loss was balanced by a minor infection period in April/May and a major one extending from August until January. The fish continued to accumulate infections until they reached a size of about 130 mm, but thereafter intensity fluctuated about the level reached. D. spathaceum infections similarly increased throughout the period of study, and there was a suggestion of a wave of infection in the spring. This parasite has a much longer life span, and levels of infection increased with fish size, only falling in the largest, and therefore oldest, hosts. The major changes in the parasite populations in the roach were reflected, to a lesser extent, in the rudd. Both species were over-dispersed, but the data from roach was too heterogeneous to fit to any theoretical models, whereas that from the rudd was found to conform to a Negative Binomial distribution.
Comparative stability of two salmonid viruses and poliovirus in fresh, estuarine and marine waters

The inactivation rates in the aquatic environment of two fish pathogens, infectious pancieatic necrosis virus (IPNV) and infectious haematopoietic necrosis virus (IHNV), were compared with that of poliovirus type 1 as a representative of the human enterovirus group. The survival studies were performed using untreated fresh, estuarine and sea water samples held at 15 and 20°C. The results indicated that the salmonid viruses survived longer than poliovirus in the saline waters, whereas in fresh water poliovirus was the most stable of the three viruses. IPN virus proved to be most stable in estuarine water at 15°C, whereas the survival of IHN virus was favoured in fresh water. We also observed that at 20°C the inactivation rate for each virus was independent of salt concentration in estuarine and sea water. Although temperature exhibited a marked effect on virus stability in fresh water, the salmonid viruses presented similar survival patterns at both temperatures in sea water. In general the period of greatest viral inactivation correlated with higher bacterial numbers in the waters.
Gibberellins and the floral transition in Sinapis alba

The putative role of gibberellins in the transition to flowering was investigated in Sinapis alba, a caulescent long-day (LD) plant. It was observed that: (1) physiological doses of exogenous gibberellins (GA 1 , GA 3 , GA 9 ) do not cause the floral shift of the meristem when applied to plants grown in short days but have some positive effect on the flowering response to a suboptimal LD; no inhibition was observed in any case; (2) GA-biosynthesis inhibitors (prohexadione-Ca and paclobutrazol) considerably inhibit stem growth but have some negative effect on flowering only when a suboptimal LD is given; and (3) the floral transition induced by one 22-h LD does not correlate with any detectable change in GA content of the apical bud, of the leaves, and of the phloem exudate reaching the apex. Taken together, these results suggest that GAs do not act as a major signal for photoperiodic flower induction in Sinapis.
Movement of apterous Sitobion avenae (Homoptera: Aphididae) in response to leaf disturbances caused by wind and rain

The effect of wind and rain on initiation of dispersal and subsequent distances moved by apterous Sitobion avenae was quantified in five laboratory experiments. Wind duration and type (steady and gusting), rain duration and intensity, and a combination of wind and rain were investigated. With increased duration of wind there was an increase in the average distance aphids moved. There was less movement when aphids were exposed to gentle gusting, than to steady wind or strong gusting. With increased duration of rain there was an increase in the proportion of aphids lost from plants. Under heavy rain, the proportion of aphids off the release plant, the distance moved by them and the proportion of aphids lost, was greater than for drizzle or light rain. When wind and rain were compared, rain had the greater impact on aphid dispersal. It was concluded that leaf disturbances caused by strong gusts of wind or large rain droplets are of considerable importance in the initiation of aphid dispersal, but that wetness alone is not.
NUTRIENT CONTROLS ON NITROGEN UPTAKE AND METABOLISM BY NATURAL POPULATIONS AND CULTURES OF TRICHODESMIUM (CYANOBACTERIA)

The effects of inorganic nutrient (ammonium [NH4+] and nitrate [NO3−]) and amino acid (glutamate [glu] and glutamine [gln]) additions on rates of N2 fixation, N uptake, glutamine synthetase (GS) activity, and concentrations of intracellular pools of gln and glu were examined in natural and cultured populations of Trichodesmium. Additions of 1 μM glu, gln, NO3−, or NH4+ did not affect short‐term rates of N2 fixation. This may be an important factor that allows for continued N2 fixation in oligotrophic areas where recycling processes are active. N2 fixation rates decreased when nutrients were supplied at higher concentrations (e.g. 10 μM). Uptake of combined N (NH4+, NO3−, and amino acids) by Trichodesmium was stimulated by increased concentrations. For NO3−, proportional increases in NO3− uptake and decreases in N2 fixation were observed when additions were made to cultures before the onset of the light period. GS activity did not change much in response to the addition of NH4+, NO3−, glu, or gln. GS is necessary for N metabolism, and the bulk of this enzyme pool may be conserved. Intracellular pools of glu and gln varied in response to 10 μM additions of NH4+, glu, or gln. Cells incubated with NH4+ became depleted in intracellular glu and enriched with intracellular gln. The increase in the gln/glu ratio corresponded to a decrease in the rate of N2 fixation. Although the gln/glu ratio decreased in cells exposed to the amino acids, there was only a corresponding decrease in N2 fixation after the gln addition. The results presented here suggest that combined N concentrations on the order of 1 μM do not affect rates of N2 fixation and metabolism, although higher concentrations (e.g. 10 μM) can. Moreover, these effects are exerted through products of NH4+ assimilation rather than exogenous N, as has been suggested for other species. These results may help explain how cultures of Trichodesmium are able to simultaneously fix N2 and take up NH4+ and how natural populations continue to fix N2 once combined N concentrations increase within a bloom.
The shoot apical meristem: an historical perspectiveThis review is one of a selection of papers published on the Special Theme of Shoot Apical Meristems.

Although much of the current investigation of shoot apical meristems is in the realm of molecular genetic analysis, it is important that previous structural and functional studies not be overlooked as essential background to these studies. Since Caspar Friedrich Wolff described the shoot apical meristem in 1759, many and varied interpretations have arisen. In the early 19th century, the apical cell was recognized in seedless vascular plants and this interpretation was extended to seed plants. However, by the 1860s, this view was replaced in seed plants by the histogen concept, which recognized meristem layers in the apical meristem giving rise to specific tissues. In 1924, the tunica–corpus interpretation of angiosperm shoot apices became widespread, the two regions being distinguished by different planes of cell division. In the 1950s, the “meristeme d’attente” concept appeared in France, which argued that the central region of the apex remained essentially inactive until the onset of flowering. Meanwhil.
Haematological responses in the European eel, Anguilla anguilla L., to sublethal infestation by Anguillicola crassus in a thermal effluent of the Swedish Baltic

Haematological variations were studied in a European eel population, Anguilla anguilla L. , naturally infested by the sanguivorous nematode Anguillicola crassus. This occurred off the Swedish Baltic coast in an area receiving heated cooling water from a nuclear power station. The erythrocyte count, haematocrit, leucocrit, haemoglobin concentration, mean corpuscular volume, mean corpuscular haemoglobin and mean corpuscular haemoglobin concentrations, the various cell types in peripheral blood, serum iron concentration, the amount of total serum protein, and scrum protein fractions α1, β1, α2, β2 and γ were all measured. Each variable was correlated to: (1) the intensity of infestation, i.e. number of parasites per host; and (2) a parasitization index, i.e. the weight of parasites per somatic weight of the host. Most variables showed no or only minor reactions to the infestation. However, a marked increase in the γ-fraction of scrum proteins, reduced lymphocyte numbers and increased granulocyte numbers are indicative of a humoral and cellular immune response.
A High Roughage System for Raising Calves Based on the Early Development of Rumen Function. VII. Utilization of Grass Silage, Pasture, and Pelleted Alfalfa Meal

Roughage plays an important part of the feeding of young calves. For several years studies have been in progress at the Ohio Experiment Station involving the feeding of various kinds of hay as the only roughage in a high roughage feeding system. The study herein reported was planned to obtain information on growth and rumen digestion when using pasture, grass-legume silage, and pelleted alfalfa meal as substitutes or partial substitutes for hay in the high roughage system. Editor.
Changes in life-history parameters of Daphnia longispina (Cladocera, Crustacea) as a function of water chemistry

Health, distribution and life-history of aquatic crustaceans strongly depend on water hardness. However hardness is commonly correlated with alkalinity, which highlights the need to assess the joint effects of both hardness and alkalinity. This study aims to test the hypothesis that water hardness and alkalinity affect the life-history parameters (growth, reproduction and population growth rate) of D. longispina . Following this, life table experiments were carried out in order to study the effects of high levels versus low levels of water hardness and alkalinity. Low levels of hardness and alkalinity caused a significant reduction in the growth of daphnids after a 7-days period, which augmented during the 21-day-test period reaching a 14.5% reduction compared to high hardness and alkalinity. Allied to the reduced growth, daphnids reared at low hardness and alkalinity showed delayed reproduction, increased body length at first reproduction, reduced fertility at first brood and, consequently, a 36.6% reduction in total fertility, compared to daphnids reared at high hardness and alkalinity. Accordingly, daphnids with the same size produced smaller broods at low hardness and alkalinity, reflecting a direct effect of water chemistry on daphnids reproduction. The impaired growth and reproduction at low hardness and alkalinity levels was likely a consequence of increased maintenance costs, and was not related to changes in the feeding activity. Population growth rate of daphnids reared at low hardness and alkalinity was 13.4% lower than that of daphnids reared at high hardness and alkalinity. Thus, despite D. longispina can survive at low hardness and alkalinity, their life-history parameters are significantly affected. This study raises concerns about the effects of decreasing hardness and alkalinity, which has been reported in Europe and North America, on populations of D. longispina and, thus, on the structure of aquatic ecosystems.
STUDY OF THE ASSIMILATION OF PROLINE BY BREWING YEASTS

The problem of the incomplete assimilation of proline by brewing yeasts has been approached by studying growth on synthetic media under various conditions, by examining a catabolic reaction which could explain non-degradation under anaerobic conditions and by following the penetration of l-14C proline into the yeast cells. Demonstrations have been made that proline oxidase, the enzyme responsible for the first catabolic reaction of l-proline, requires the participation of cytochrome c to operate and therefore needs the presence of molecular oxygen, and that the permease responsible for the transport of proline is, under normal brewery conditions, repressed by other amino acids of wort. Permease derepression, which should normally occur after the complete consumption of the other amino acids, is made impossible because of the strong anaerobic conditions achieved at that stage.
Anomalous Vessel Elements in Wilty-Dwarf Tomato

Vessel elements of wilty-dwarf tomatoes (Lycopersicon esculentum Mill.) have anomalous end walls instead of a simple perforation plate. These end walls, which occur in various forms in all xylem of the plant, offer a considerable barrier to conduction and account for the wiltiness of wilty-dwarf plants.
A Note on Why Natural Selection Leads to Complexity

While science has accepted biological evolution through natural selection, there is no generally agreed explanation for why evolution leads to ever more complex organisms. Evolution yields organismic complexity because the universe is, in its very fabric, inherently complex, as suggested by Ilya Prigogine's work on dissipative structures. Because the universe is complex, increments in organismic complexity yield survival benefits: (1) more efficient extraction of energy and matter, (2) more flexible response to vicissitudes, (3) more effective search. J.J. Gibson's ecological psychology provides a clue to the advantages of sophisticated information processing while the lore of computational theory suggests that a complex computer is needed efficiently to perform complex computations (i.e. sophisticated information processing).
Data on molecular taxonomy and genetic diversification of the European Hermit beetles, a species complex of endangered insects (Coleoptera: Scarabaeidae, Cetoniinae, Osmoderma)

A molecular analysis was carried out on the European hermit beetles (the Osmoderma eremita species complex) to explore their genetic diversification and the robustness of previous morphologically based taxonomic arrangements. Complete sequences of mtDNA cytochrome C oxidase I gene were obtained from 26 individuals. Mean levels of interspecific sequence divergence ranged from 0.044 to 0.186. The results indicate a clear-cut distinction between two clades. The first one includes the W-European O. eremita Scopoli 1763; and the two Italian endemic taxa Osmoderma italicum Sparacio, 2000 and Osmoderma cristinae Sparacio, 1994; from southern peninsular Italy and Sicily, respectively. The second one includes the widespread E-European Osmoderma barnabita; and the southern Balcanic Osmoderma lassallei Baraud and Tauzin, 1991 from Greece and European Turkey. Within the two clades, molecular and morphological data well support a specific rank for O. lassallei and O. barnabita on one side, and for O. eremita and O. cristinae on the other side, while the taxonomic position of O. italicum, more closely related to O. eremita, is still uncertain. Current geographical distribution, interspecific genetic diversification, and very low levels of intraspecific genetic divergence in western European populations of O. eremita sensu stricto are hypothesized to be the result of multiple speciation events (mainly occurred in refugial forest areas of the Italian and Balkan peninsulas and Sicily before and during the Pleistocene glacial peaks), followed by fast post-glacial northward and westward expansion of some species.
Isolamento do gene ALS e investigação do mecanismo de resistência a herbicidas em Sagittaria montevidensis

California arrowhead (Sagittaria montevidensis Cham. & Schlecht) is an aquatic weed often found in rice paddy fields. Several biotypes of California arrowhead resistant to ALS-inhibiting herbicides were found in Brazil and in several rice fields worldwide. The objective of this study was to sequence the ALS gene of California arrowhead and to identify the occurrence of mutations related to target site insensitivity as the mechanism of herbicide resistance. The plant material consisted of seeds collected in rice paddy fields located in the state of Santa Catarina, Brazil. Nine pairs of primers were designed for the amplification of the domains C, A and D of the ALS gene. PCR reactions with four pairs of primers resulted in amplification of fragments with size close to expected, ranging from 360 to 393 nucleotides. These sequences showed high homology to the standard ALS gene Arabdopsis thaliana and rice having only three point mutations. One of these mutations was Pro 197 Phe that is related with herbicide resistance in several weeds. The sequences obtained indicated that the ALS gene evaluated was heterozygous. These results suggest the occurrence of insensitivity of the site of action as the mechanism of resistance to ALS-inhibitors herbicides in California arrowhead. The prevention and control of resistance to ALSinhibitors in California arrowhead should be based on the rotation of herbicides with different mechanisms of action.
Sexual selection in the ring-necked pheasant: a review

The common pheasant, Phasianus colchicus, is now considered a classic example of the difficulty of establishing a clear distinction between inter- and intrasexual selection since a role for male spurs as cues used by females in mate choice has been reported. Field and experimental studies on sexual selection in the ring-necked pheasant show that the dimorphic morphological (and behavioural) male traits have a dual function according to the armament-ornament model. They are weapons or reliable signals of male quality directed both to females and rivals, and the relative importance between them depends on a suite of factors affecting the decision-making processes of females, including the outcome of male-male encounters. Different mechanisms and models of sexual selection have been suggested in order to classify the overall competitive strategies found in nature; but the amount of empirical data on the evolution of epigamic traits suggests that what determines the reproductive success of males is a complex .
Dynamics of challenge infections of Gyrodactylus bullatarudis Turnbull (Monogenea) on guppies, Poecilia reticulata (Peters)

Comparison of the population dynamics of Gyrodactylus bullatarudis o fish that were reinfected at 0, 1, 2, 4, or 6 weeks post-recovery from an initial, infection were based on the following parameters: percentage establishment, recovery and death, mean peak parasite burden, mean time to peak burden, mea duration of infection, mean time to death. Of fish that recover from an initial, infection, some are immediately susceptible to a challenge infection. Other fish are able to harbour a challenge infection hut parasite numbers increase less and the infection is of shorter duration than the initial. These fish regain their fu susceptibility within 4-6 weeks post-recovery. A third group of fish become totally refractory to reinfection and only slowly regain their ability to support an infection Thus even at 6 weeks post-recovery they are only partially susceptible t reinfection. It is probable that the three groups in fact represent a continuum increasing susceptibility to challenge infection.
Recovery of plants and histological observations on advanced weed stages after glyphosate treatment

Some weeds treated with the recommended dose rates of glyphosate recover after the application. An explanation of this phenomenon is needed to avoid incomplete control and the potential spread of resistance. The distributions of glyphosate and of shikimate levels within treated plants were therefore analysed, and plant reactions were investigated via histological examinations. It was found that glyphosate was translocated from Amaranthus palmeri leaves to roots within 48 h following treatment. Changes in the phloem of different weed species became visible after 3 days. After 4 days, shikimate accumulation was highest in stem tips and decreased towards the base of plants. Necrosis of pith cells started at the same time. Yellowing of leaves, stem curvature and wilting were observed after 1 week. Herbicide-induced polyphenols and lignin in the intercellular space suggest that glyphosate phytotoxicity is not based solely on the shikimate pathway. It seems to be linked to the decay of vascular tissues and of pith, but not to the transport of glyphosate into apical meristems. Meristematic tissue surrounding the pith survived and gave rise to new buds in Amaranthus plants. These findings are important for the characterisation of plants that escape herbicide treatment and for the search for new control tools.
AN IN VITRO NITRATE REDUCTASE ASSAY FOR MARINE MACROALGAE: OPTIMIZATION AND CHARACTERIZATION OF THE ENZYME FOR FUCUS GARDNERI (PHAEOPHYTA) 1

Measurement of the activity of the enzyme nitrate reductase (NR) may provide a useful index of nitrogen metabolism in marine macroalgae. In several species, including Fucus gardneri P. C. Silva, in vitro assays previously failed to detect NR activity, necessitating the use of in situ (or so‐called“in vivo”) assays, which are more loosely controlled and lead to dafficulties in assessing enzyme characteristics such as the half‐saturation constant (Km). In this paper, we describe an in vitro NR assay developed for F. gardneri, in which tissue was homogenized using liquid nitrogen prior to the assay. In contrast to previous studies, enzyme activity was always detectable in F. gardneri collected directly from the field at levels up to 30 nmol nitrate converted to nitrite·min−1·g−1 wet weight. The effect of a variety of compounds, commonly added to NR extraction buffers, were tested. Additions of protease inhibitors, bovine serum albumin, and ethylenediamine tetraacetic acid had no consistent effects on NR activity, while polyvinyl pyrrolidone, potassium ferricyanide, and flavin adenine dinucleotide significantly decreased activity. The half‐saturation constant (Km) for NADH was 0.18 (± 0.05) mM and for nitrate, Km=0.99 (±0.41) mM. Significant NR activity was detected without the addition of nitrate, suggesting that internal pools of nitrate averaging approximately 20 μmol NO3−·g−1 wet weight were present in F. gardneri in February. The distribution of NR activity within the plant was highly variable between individuals, but activities were approximately 5‐fold lower in the stipe than in midregions. In plants freshly sampled from the field, NR activity increased 7‐fold from February to March, then fell to near‐February levels by April. These changes in activity may correspond to seasonal changes in growth rate. The assay, optimized for F. gardneri, was used in several different macroalgal species from different taxa: Porphyra sp. , Coralina vancouveriensis Yendo, Ulva sp. , Enteromorpha intestinalis (Linnaeus) Nees, Macrocystis integrifolia Bory; and Costaria costatum (C. Agardh) Saunders. For all species tested, NR activity was detectable and, except for one species (Porphya sp.), was equal to or greater than activities measured by other workers using in vivo or in vitro assays for plants under similar conditions.