Miracle-dz/UniFAR-FTUs huggingface dataset:
Regulation of Populations with Nonoverlapping Generations by Microparasites: A Purely Chaotic System

Consider a plant or animal population with discrete, nonoverlapping generations whose density is regulated by a lethal pathogen that spreads in epidemic fashion throughout each generation before the reproductive age is attained. Surprisingly, this simple and deterministic system has no stable point and no stable cycles, but rather exhibits chaotic dynamics (in other words, the map relating the magnitude of the population in generation t + 1 to that in generation t has a truly ergodic invariant measure). The model has pedagogic interest as an example in which simple and natural assumptions lead to purely chaotic dynamical behavior. This population model, with its relatively transparent dynamics, also helps us to understand how the frequency- and density-dependent effects that pathogens can introduce in the population genetics of host-parasite associations can be exceedingly complicated, and can lead to polymorphisms that vary chaotically.
Distribution and function of proteoid roots and other root clusters

Proteoid roots are bottlebrush-like clusters of rootlets which form along lateral roots. They are characteristic of most species of the Proteaceae, which are mainly distributed in Australia and South Africa. Homologous root clusters are present in species of the Casuarinaceae, Mimosaceae, Fabaceae, Myricaceae and Moraceae. Many similarities exist between these species in relation to morphology and function of root clusters. Many are non-mycorrhizal and are highly efficient in phosphorus (P) acquisition. In these species, proteoid roots and proteoid-like root clusters are abundant when grown on infertile soils. Their formation is predominantly affected by the P status of the plants, being induced at low P levels and repressed at high P levels. Proteoid roots and proteoid-like root clusters play an important role in acquisition of P and other mineral nutrients. Although increase in root surface area may be a contributing factor, in many species these roots excrete large amounts of organic acids and phenolics. The excretion of these compounds in a small soil volume gives rise to extensive nutrient mobilization by acidification, reduction and chelation of sparingly soluble forms of P and micronutrients such as Fe and Mn.
Chemical and morphological segregation of Alternaria arborescens, A-infectoria and A-tenuissima species-groups

Correct morphological identification of Alternaria is important and demands a combination of modern standardised methods and up-to-date literature. The production of secondary metabolites has previously been used as a means of identification and classification. In this study, 153 fungal isolates belonging to the genus Alternaria were examined. They were grown under standardised conditions and subjected to morphological and chemical examination. All isolates were grouped according to their three-dimensional sporulation pattern on potato carrot agar and their colony colour on dichloran rose bengal yeast extract sucrose agar (DRYES). After extraction, all isolates were analysed by a high performance liquid chromatograph equipped with a diode array detector and the resulting metabolite profiles were subjected to multivariate statistic analyses. The analyses of metabolite profiles showed that the isolates could be divided into three major species-groups that were morphologically identifiable as the A. infectoria species-group, the A. arborescens species-group and the A. tenuissima species-group. The A. infectoria species-group is chemically very different from both the A. arborescens and the A. tenuissima species-groups with only a few metabolites in common. None of the 35 A. infectoria species-group isolates produced any known metabolites and all had white or greyish white colonies on DRYES. The A. arborescens species-group and the A. tenuissima species-group, shared most of the known metabolites and had colonies of various shades of green on DRYES. One cluster of isolates belonging to the A. tenuissima species-group was able to produce tentoxin, which has not been reported previously from any A. tenuissima isolate. The results suggest that each species-group contains several taxa and these taxa need to be formally described before species specific metabolite profiles can be established.
Contrasting Windstorm Consequences in Two Forests, Itasca State Park, Minnesota

Thunderstorm winds ( 25-35 m/s) often damage scattered trees in northern Minnesota forests. Following one moderate windstorm on 3 July 1983, I surveyed damaged trees within two Itasca Park study areas (1) to identify mortality patterns and their correlates, (2) to evaluate windstorm consequences for shade-intolerant species, and (3) to investigate formation of light-gaps. Risk of direct wind damage was predicted best by tree size (in both stands) and either tree species (in a Pinus/Acer stand) or species wood strength (in a Pinus/Abies stand). However, the overall risk of mortality, combining direct wind damage and damage from falling trees, was more complex. Tree mortality in the Pinus/Acer study area was related to tree size, species, species wood strength, and incidence of species-specific fungal patho- gens. Mortality in the Pinus/Abies study area, where many understory trees were killed, was not predictable on the basis of tree size, but mortality risk was affected by tree species and species wood strength (data on fungal pathogens were unavailable for this stand). Within most populations, the size distribution of windstruck trees differed from the pop- ulation size distribution. However, mortality risk, including that from falling trees, in- creased with tree size only for Populus tremuloides. In one study area, smaller trees were most vulnerable within the Picea and Pinus strobus populations. The difficulty of gener- alizing about windstorm consequences is illustrated by large intraspecific variation in amount of damage between different populations of Betula papyrifera, Pinus resinosa, and Pinus strobus. For shade-intolerant species expected to benefit from disturbance, windstorm conse- quences differed in the two stands, despite shared postfire origins and several tree species in common. In the Pinus/Acer forest, heavy mortality to shade-intolerant Populus tre- muloides, Pinus resinosa, and Pinus strobus combined with a well-developed, windfirm understory and infrequent light-gap formation to benefit existing shade-tolerant, windfirm Acer saccharum and tall shrubs. In the nearby Pinus/Abies forest, the windstorm produced more regeneration opportunities for shade-intolerant species (Betula papyrifera, Populus tremuloides, Fraxinus pennsylvanica), because the shade-tolerant understory species of this stand (Abies balsamea, Picea glauca) were more heavily damaged, and because more light- gaps formed, although such light-gaps were small relative to published gap size thresholds for tree establishment. Differences between the two communities in their responses to the same storm event appear to result from differences in forest structure and differences in the windfirmness of shade-tolerant understory taxa.
Mast seeding of Chionochloa (Poaceae) and pre-dispersal seed predation by a specialist fly (Diplotoxa, Diptera: Chloropidae)

Abstract Levels of seed predation were recorded between 1986 and 1992 in Chionochloa pattens, C. oreophila, C. flavescens, C. macra, and C. crassiuscula populations at various altitudes at three sites in Canterbury. There were consistently high levels of attack by a chloropid fly, Diplotoxa similis: between 22 and 94% of florets showed evidence of fly damage, except at higher altitudes (decreasing to 2% in C. pattens at 1620 m) and in C. oreophila (6 – 10%). Since D. similis emerges rapidly from the pupa and since larvae possibly move between florets, the number of insects found underestimated the number of florets predated by up to 90%. Seed set varied from 2% to 59% and was negatively correlated with seed predation. Two other Chionochloa seed predators have been reported previously: a moth, Megacraspedus calamogonus, and an unidentified cecidomyiid (gall midge) larva. In this study, larvae similar to Megacraspedus were very rare, and we suggest that the unidentified cecidomyiid is actually a misidentifi.
Subsoil nitrate uptake and symbiotic dinitrogen fixation by alfalfa

Alfalfa (Medicago saliva L.) is a deeply rooted perennial that may be able to remove NO 3 from the subsoil beneath the rooting zone of annual crops. Our main objectives were to characterize the potential of two alfalfa cultivars (Agate and Ineffective Agate, an ineffectively nodulated near isoline of Agate) to remove NO 3 from the subsoil and to evaluate the influence of available subsoil NO 3 on symbiotic N 2 fixation. Low ( 0.3 mM) or high (20 mM) NO 3 -N concentrations were supplied through a subsoil irrigation system installed in a Hubbard loamy sand soil (sandy, mixed Udorthentic Haploboroll) at Beeker, MN. Nitrate uptake and N 2 fixation were evaluated during two regrowth periods using 15 N. During fall regrowth in the establishment year, supply of 20 mM 15 N-enriched NO 3 through subsoil irrigation did not decrease symbiotic N 2 fixation; during summer regrowth of the first production year, symbiotic N 2 fixation decreased only 40% (from 7.77 to 4.60 g N m -2 ). Even though it had higher yields, Agate alfalfa removed less subsoil NO 3 -N (1.52 and 5.51 g N m -2 ) than did Ineffective Agate (3.12 and 7.13 g N m -2 ) in each of two harvests where 15 N was applied. Root length and mass after 2 yr were not altered by NO 3 treatment or cultivar. This is the first time that direct measurements of subsoil nitrate removal have been made in the field for an N 2 -fixing crop. Because it is unlikely that differences in NO3 uptake efficiency could account for such cultivar differences, we propose that assimilation of atmospheric N 2 reduced the capacity of the fixing crop to absorb NO 3 . These results suggest that non-N 2 -fixing alfalfa cultivars would be more useful for bioremediation of nitrate-contaminated sites than standard cultivars.
Amino Acid Sequence and Molecular Structure of an Alkaline Amylopullulanase from Bacillus That Hydrolyzes α-1,4 and α-1,6 Linkages in Polysaccharides at Different Active Sites*

An amylopullulanase from alkalophilic Bacillus sp. KSM-1378 hydrolyzes both α-1,6 linkages in pullulan and α-1,4 linkages in other polysaccharides, with maximum activity in each case at an alkaline pH, to generate oligosaccharides (Ara, K., Saeki, K., Igarashi, K., Takaiwa, M., Uemura, T., Hagihara, H., Kawai, S., and Ito, S. (1995) Biochim. Biophys. Acta 1243, 315-324). Here, we report the molecular cloning and sequencing of the gene for and the structure of this enzyme and show that its dual hydrolytic activities are associated with two independent active sites. The structural gene contained a single, long open reading frame of 5,814 base pairs, corresponding to 1,938 amino acids that included a signal peptide of 32 amino acids. The molecular mass of the extracellular mature enzyme (Glu33 through Leu1938) was calculated to be 211,450 Da, a value close to the 210 kDa determined for the amylopullulanase produced by Bacillus sp. KSM-1378. The amylase and the pullulanase domains were located in the amino-terminal half and in the carboxyl-terminal half of the enzyme, respectively, being separated by a tandem repeat of a sequence of 35 amino acids. Four regions, designated I, II, III, and IV, were highly conserved in each catalytic domain, and they included a putative catalytic triad Asp550-Glu579-Asp645 for the amylase activity and Asp1464-Glu1493-Asp1581 for the pullulanase activity. The purified enzyme was rotary shadowed at a low angle and observed by transmission electron microscopy; it appeared to be a “castanet-like” or “bent dumbbell-like” molecule with a diameter of approximately 25 nm.
Temporal changes in key factors and key age groups influencing the population dynamics of female red deer

Summary 1. We use structured demographic accounting to decompose the contribution to the variance in relative population growth between 1971 and 1997 in female red deer on Rum, Scotland, in terms of different fitness components and age categories. 2. During the first 10 years (1971–80) the variance in relative population growth was small (0·00246) as the population grew from 58 to 148 having been culled previously. After this the relative variance in population growth increased to 0·00575 between 1981 and 1989, and increased again to 0·00848 between 1990 and 1997. 3. In the first phase of population growth (1971–80) changes in the birth rate contributed most to the variance in relative population growth (30%), then adult winter survival (23%), with calf summer and calf winter survival contributing less than 10%. Birth rate tended to covary strongly with adult winter survival, and to a lesser extent with calf winter survival. 4. The contribution of birth rate to the variance in relative population growth diminished to less than 5% in both the periods 1981–89 and 1990–97. In contrast, the contribution of adult winter survival increased to 36% in 1980s and 40% in 1990s. At the same time, the covariation of adult winter survival with calf winter survival increased successively to reach 40% in 1990–97. 5. Changes in population age structure were small and contributed little to the variance in relative population growth (≈ 1% over the entire study). In the 1970s the 5–7-year-old group contributed most (23%) to the variance in relative population growth, though this covaried with 8–12-year-olds. In the 1980s the 8–12-year-olds contributed most (27%) and now the covariation was with older animals (> 12-year-olds). This pattern persisted in the 1990s, though there was covariation with 5–7-year-olds too. 6. Birth rate, calf winter survival and adult winter survival were all density-dependent. The strength of density dependence within each vital rate did not differ between the 1970s, 1980s and 1990s; however, there were differences in the means of these vital rates relative to population size between the three periods. 7. The implications of temporal changes in the most important vital rates, the ‘key factors’, contributing to the variance in relative population growth rate are discussed.
The Novel Recognition Site in the C-Terminal Heparin-Binding Domain of Fibronectin by Integrin α4β1 Receptor on HL-60 Cells

Abstract The hematopoietic cell recognition sites of human fibronectin (FN) are the Arg–Gly–Asp–Ser (RGDS) sequence recognized by widely distributed integrin receptor α5β1 and the type III connecting segment (III CS) containing two cell-binding sites, designated CS1 and CS5, that are recognized by the α4β1 receptor. The C-terminal heparin-binding domain of FN (Hep II) has recently been demonstrated to support adhesion of α4β1-dependent melanoma cells [A. P. Mould and M. J. Humphries (1991) EMBO J. 10, 4089–4095]. Previously we demonstrated that this region of FN mediated binding of FN to HL-60 cells (acute promyelocytic leukemia cell line) by direct interaction independently of RGD and CS1 [H. Fujita et al., (1995) Exp. Cell Res. 217, 484–488]. In this study we have characterized a novel site in the Hep II region for binding to HL-60 cells. α4β1 and α5β1 were expressed on HL-60 cells, while α2β1 and α3β1 were not present, as shown by flow cytometry using monoclonal antibodies specific for the different integrins. Anti-α4β1 (P4C2) and anti-β1 (JB1a) antibodies inhibited binding of a 29-kDa dispase-digestive fragment of FN to HL-60 cells. This fragment contains the C-terminal heparin-binding domain of FN but lacks CS1 and CS5. Only the peptide representing the sequence from Val 1866 to Arg 1880 , designated E1, inhibited the binding of the 29-kDa fragment to HL-60 cells. The active region of this peptide was a sequence of Thr–Asp–Ile–Asp–Ala–Pro–Ser (TAI- DAPS), which is homologous to Leu–Asp–Val–Pro–Ser (LDVPS) derived from the active site of CS1. Furthermore, labeled E1 peptide directly bound to HL-60 cells. The anti-α4β1 antibody (P4C2) inhibited this interaction. These results indicate that the site of binding to hematopoietic cells is present in the Hep II region of FN and the definition of the chemical structure of FN clarifies a fundamental mechanism of cell invasion of the extracellular matrix.
Objective analysis of seafood quality

Abstract Canadian seafood quality has traditionally been examined by the subjective parameters of odor, color, flavor and appearance. Also, Canadian seafood products have most often been marketed on a one price system; products of high and mediocre quality being sold at the same price. A principal advantage of objective quality assessment is the ability to assign meaningful numerical scores to raw material and finished product, thus permitting adjustment of market prices and providing a cash incentive to fishermen, processors and retailers to maintain high quality standards. Development of rapid, inexpensive objective techniques for seafood quality evaluation has been the focus of research in our laboratories during the past several years. Rapid procedures for the analysis of amines, nucleotides and ammonia are presented and the applicability of each for the overall evaluation of seafood quality discussed.
Growth and Mortality of Red Snappers in the West-Central Atlantic Ocean and Northern Gulf of Mexico

Abstract Age, growth rates, mortality, and length-weight relationships were determined for red snappers Lutjanus campechanus from two areas in the west central Atlantic Ocean and two in the northern Gulf of Mexico. Growth rates varied only slightly among areas. The von Bertalanffy growth equation was Lt = 975(1 - e−0.16(t-0.0)) for fish from the Atlantic and Lt = 941(1 - e− 0.17(t + 0.1)) for fish from the Gulf of Mexico, where Lt is length at age t in years. The length-weight equation differed among areas, but no difference was evident between sexes. This equation for fish from all areas pooled was W = 2.04 × 10−5TL2.953, where W is weight in grams and TL is total length in mm. Significant differences were found in total instantaneous mortality rates. The rate ranged from 0.39 for fish off the coast of North Carolina and South Carolina to 0.78 for fish off the coast of Louisiana. Age of full recruitment to the fishery ranged from 2 years off Louisiana to 6 years off the Carolinas. Fishing mortality appea.
ELECTRON MICROSCOPIC CYTOCHEMICAL STUDIES ON SULFATED GLYCOSAMINOGLYCANS IN RAT MAST CELL GRANULES

Electron microscopic cytochemical studies have been made on sulfated glycosaminoglycans in mast cell granules from the rat peritoneal cavity by means of combined alcian blue (AB) pH 1.0-phosphotungstic acid (PTA) staining and enzyme (heparinase or chondroitinase ABC) digestion or chemical modification (nitrous acid) procedures. The results obtained revealed that the mast cell populations from the rat peritoneal cavity are grouped into at least three cell types on the basis of the molecular species of sulfated glycosaminoglycans contained in the cytoplasmic granules, the first cell type occupying the majority of the cell population with cytoplasmic granules containing primarily heparin, the second cell type being of an exceedingly small proportion with cytoplasmic granules containing primarily isomeric chondroitin sulfate (D and/or E), and the third cell type (intermediates between the first and second types) constituting a relatively small proportion with cytoplasmic granules containing two kinds of cytoplasmic granules containing heparin and isomeric chondroitin sulfate (D and/or E) respectively. In addition, unique substructures of cytoplasmic granules containing different sulfated glycosaminoglycans were disclosed such as tubular or thin thread-like elements, interstitial vesicles and surface spine-like figures.The present results are taken to represent the first electron microscopic cytochemical evidence that mast cell populations are heterogeneous in terms of molecular species of sulfated glycosaminoglycans contained in the cytoplasmic granules in mammals.
Eastern and southern African strains of Xanthomonas campestris pv. vasculorum are distinguishable by restriction fragment length polymorphism of DNA and polyacrylamide gel electrophoresis of membrane proteins

Thirty strains of Xanthomonas campestris pv. vasculorum were examined using restriction fragment length polymorphism (RFLP) of genomic DNA and polyacrylamide gel electrophoresis (PAGE) of membrane proteins. Previous reports suggested the existence of two geographical strains of this pathogen, occurring primarily in eastern and southern Africa. Seventeen southern African strains from South Africa and Zimbabwe formed an apparent clonal population with distinct and unique RFLP patterns and membrane protein profiles. Similarly, 11 eastern African strains from Mauritius and Reunion and two from Australia were also related, indicating the possible existence of two distinct organisms separated by geographical locality but otherwise involved in the same disease. Our data confirm the long-held hypothesis that eastern African strains of X. c. pv. vasculorurn are distinct from the southern African strains. The fact that these two distinct strains cause the same disease, gumming disease of sugar cane, suggests the possible independent development of the pathogen in these two localities.
Filtration and oxygen consumption in mussels,Mytilus edulis, with and without pea crabs,Pinnotheres maculatus

Filtration rates and oxygen consumption rates were measured in mussels (Mytilus edulis) with and without pea crabs (Pinnotheres maculatus). Noninfested mussels had a significantly higher rate of oxygen consumption per hour (0.578 ml±0.012) than did infested mussels (0.352 ml±0.012). There was no significant effect of pea crab size on mussel respiration. Filtration rates of infested mussels were significantly lower than those of uninfested mussels. Assimilation efficiency was not significantly affected by pea crab infestation. The relationship between body size and oxygen consumption inP. maculatus is given by the following equation: {ie264-1} W0.626, where {ie264-2} is oxygen uptake (ml h−1), and W is dry weight (g). There was no difference between the sexes. It is concluded that the decreased oxygen consumption observed in infested mussels is not due to limitation of oxygen availability, but rather reflects a real metabolic response to the presence of the symbiont and the concomittant deprivation of food to the host. The effect is probably reversible, that is, damage can be compensated for after the symbiont has vacated the mussel, depending upon the period of infestation. Our results indicate that the mussels infested by pea crabs may be at an energetic disadvantage relative to mussels without pea crabs.