QUALITATIVE STUDIES OF SOIL MICRO-ORGANISMS: III. INFLUENCE OF PLANT GROWTH ON THE CHARACTER OF THE BACTERIAL FLORA

1940 ◽  
Vol 18c (2) ◽  
pp. 42-53 ◽  
Author(s):  
A. G. Lochhead
Keyword(s):  
Physiological Activity ◽  
Bacterial Flora ◽  
Soil Microflora ◽  
Pronounced Increase ◽  
The Family ◽  
Qualitative Nature ◽  
Selective Plating ◽  
Genus Corynebacterium ◽  
Micro Organisms

Comparative studies of the relative incidence of bacterial types occurring in the rhizosphere of different plants and in control soils indicated that the qualitative nature of the soil microflora is markedly influenced by the growing plant. In the rhizosphere Gram-negative rods are proportionately increased while Gram-positive rods, coccoid rods, and spore-forming types are relatively less abundant.The majority of bacteria isolated from soil by non-selective plating are forms included in the family Proactinomycetaceae (Jensen's classification). Of these by far the largest group consists of members of the genus Corynebacterium. In the rhizosphere proactinomycetes as a whole are relatively less abundant, with the Corynebacterium (non-motile) group likewise depressed. However, closely related motile forms classed as Mycoplana are preferentially stimulated.In the rhizosphere the bacteria show definitely greater physiological activity than in soil distant from the plant. Not only is there a notably greater proportion of motile forms, and a pronounced increase in the incidence of chromogenic types, but also a higher incidence of liquefying bacteria and of those able to affect glucose.A comparison of the rhizosphere of certain plant varieties resistant and susceptible respectively to soil-borne disease showed differences of a qualitative nature in the bacterial flora suggestive of a greater "rhizosphere effect" in the case of the susceptible varieties studied. Results point to the possibility that resistance may be associated with a selective action of root excretions on the saprophytic soil microflora.

QUALITATIVE STUDIES OF SOIL MICRO-ORGANISMS: II. A SURVEY OF THE BACTERIAL FLORA OF SOILS DIFFERING IN FERTILITY

1938 ◽  
Vol 16c (4) ◽  
pp. 162-173 ◽  
Author(s):  
C. B. Taylor ◽  
A. G. Lochhead
Keyword(s):  
Bacterial Flora ◽  
General Character ◽  
Relative Incidence ◽  
Single Culture ◽  
Different Types ◽  
Selective Basis ◽  
Qualitative Nature ◽  
Micro Organisms ◽  
Bacterial Groups ◽  
Biochemical Action

Investigations were made, on a non-selective basis, of the qualitative nature and relative incidence of the different types of the bacterial flora of three soils differing in fertility. The organisms were classified into eight groups. Non-spore-forming short rods, of which five groups were recognized, comprised nearly 90% of all types. Gram-negative short rods formed the most prevalent single group, rather more numerous than Gram-positive short rods. Gram-variable short rods, coccoid rods and pleomorphic rods (Bact. globiforme) were regarded as definite groups. Cocci, non-spore-forming long rods and spore-formers were less prominent soil types.In spite of unequal productivity, the soils showed no outstanding differences in the relative incidence of the bacterial groups. Certain groups showed some indication of seasonal and cropping effect. The results suggest that the general character of the autochthonous (indigenous) soil flora is relatively uniform in soil of definite type, even though productivity may be greatly altered by manurial treatment.The predominant soil bacteria appear relatively inactive in single culture. Moreover considerable divergence in biochemical action was shown by apparently closely related forms. It is suggested that the bacterial flora is relatively unstable physiologically, with considerable adaptability, and that the functions of the different species are exercised most fully only under conditions of association.

Three new species, two new genera, and new family Biphragmosagittidae (Сhaetognatha) from Southwest Pacific Ocean

2011 ◽  
Vol 20 (1) ◽  
pp. 161-173
Author(s):  
A.P. Kassatkina
Keyword(s):  
New Species ◽  
Type Species ◽  
Morphological Characters ◽  
The Body ◽  
New Order ◽  
New Genera ◽  
New Family ◽  
The Family ◽  
Three New Species

Resuming published and own data, a revision of classification of Chaetognatha is presented. The family Sagittidae Claus & Grobben, 1905 is given a rank of subclass, Sagittiones, characterised, in particular, by the presence of two pairs of sac-like gelatinous structures or two pairs of fins. Besides the order Aphragmophora Tokioka, 1965, it contains the new order Biphragmosagittiformes ord. nov., which is a unique group of Chaetognatha with an unusual combination of morphological characters: the transverse muscles present in both the trunk and the tail sections of the body; the seminal vesicles simple, without internal complex compartments; the presence of two pairs of lateral fins. The only family assigned to the new order, Biphragmosagittidae fam. nov., contains two genera. Diagnoses of the two new genera, Biphragmosagitta gen. nov. (type species B. tarasovi sp. nov. and B. angusticephala sp. nov.) and Biphragmofastigata gen. nov. (type species B. fastigata sp. nov.), detailed descriptions and pictures of the three new species are presented.

scholarly journals Ecotoxicological Assessment of Microplastics in Freshwater Sources—A Review

Water ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 56
Author(s):  
Martina Miloloža ◽  
Dajana Kučić Grgić ◽  
Tomislav Bolanča ◽  
Šime Ukić ◽  
Matija Cvetnić ◽  
...  
Keyword(s):  
Complex Problem ◽  
Living Standards ◽  
Way Of Life ◽  
Inorganic Pollutants ◽  
Ecotoxicological Assessment ◽  
Characterization Methods ◽  
Special Concern ◽  
Micro Organisms ◽  
Insight Into

High living standards and a comfortable modern way of life are related to an increased usage of various plastic products, yielding eventually the generation of an increased amount of plastic debris in the environment. A special concern is on microplastics (MPs), recently classified as contaminants of emerging concern (CECs). This review focuses on MPs’ adverse effects on the environment based on their bioactivity. Hence, the main topic covered is MPs’ ecotoxicity on various aquatic (micro)organisms such as bacteria, algae, daphnids, and fish. The cumulative toxic effects caused by MPs and adsorbed organic/inorganic pollutants are presented and critically discussed. Since MPs’ bioactivity, including ecotoxicity, is strongly influenced by their properties (e.g., types, size, shapes), the most common classification of MPs types present in freshwater are provided, along with their main characteristics. The review includes also the sources of MPs discharge in the environment and the currently available characterization methods for monitoring MPs, including identification and quantification, to obtain a broader insight into the complex problem caused by the presence of MPs in the environment.

scholarly journals Extensive Phylogenetic Analysis of Piscine Orthoreovirus Genomic Sequences Shows the Robustness of Subgenotype Classification

Pathogens ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 41
Author(s):  
Marcos Godoy ◽  
Daniel A. Medina ◽  
Rudy Suarez ◽  
Sandro Valenzuela ◽  
Jaime Romero ◽  
...  
Keyword(s):  
Phylogenetic Analysis ◽  
Genetic Variation ◽  
Sequence Analysis ◽  
Molecular Phylogeny ◽  
Phylogenetic Trees ◽  
Genomic Segment ◽  
Double Stranded Rna ◽  
The Family ◽  
Original Classification

Piscine orthoreovirus (PRV) belongs to the family Reoviridae and has been described mainly in association with salmonid infections. The genome of PRV consists of about 23,600 bp, with 10 segments of double-stranded RNA, classified as small (S1 to S4), medium (M1, M2 and M3) and large (L1, L2 and L3); these range approximately from 1000 bp (segment S4) to 4000 bp (segment L1). How the genetic variation among PRV strains affects the virulence for salmonids is still poorly understood. The aim of this study was to describe the molecular phylogeny of PRV based on an extensive sequence analysis of the S1 and M2 segments of PRV available in the GenBank database to date (May 2020). The analysis was extended to include new PRV sequences for S1 and M2 segments. In addition, subgenotype classifications were assigned to previously published unclassified sequences. It was concluded that the phylogenetic trees are consistent with the original classification using the PRV genomic segment S1, which differentiates PRV into two major genotypes, I and II, and each of these into two subgenotypes, designated as Ia and Ib, and IIa and IIb, respectively. Moreover, some clusters of country- and host-specific PRV subgenotypes were observed in the subset of sequences used. This work strengthens the subgenotype classification of PRV based on the S1 segment and can be used to enhance research on the virulence of PRV.

scholarly journals Sequence data from isolated lichen-associated melanized fungi enhance delimitation of two new lineages within Chaetothyriomycetidae

2021 ◽  
Vol 20 (7) ◽  
pp. 911-927
Author(s):  
Lucia Muggia ◽  
Yu Quan ◽  
Cécile Gueidan ◽  
Abdullah M. S. Al-Hatmi ◽  
Martin Grube ◽  
...  
Keyword(s):  
Sequence Data ◽  
Single Species ◽  
Sister Group ◽  
Asexual Propagation ◽  
Dna Sequence Data ◽  
Wide Range ◽  
The Family ◽  
Rock Inhabiting Fungi ◽  
Stable Habitat

AbstractLichen thalli provide a long-lived and stable habitat for colonization by a wide range of microorganisms. Increased interest in these lichen-associated microbial communities has revealed an impressive diversity of fungi, including several novel lineages which still await formal taxonomic recognition. Among these, members of the Eurotiomycetes and Dothideomycetes usually occur asymptomatically in the lichen thalli, even if they share ancestry with fungi that may be parasitic on their host. Mycelia of the isolates are characterized by melanized cell walls and the fungi display exclusively asexual propagation. Their taxonomic placement requires, therefore, the use of DNA sequence data. Here, we consider recently published sequence data from lichen-associated fungi and characterize and formally describe two new, individually monophyletic lineages at family, genus, and species levels. The Pleostigmataceae fam. nov. and Melanina gen. nov. both comprise rock-inhabiting fungi that associate with epilithic, crust-forming lichens in subalpine habitats. The phylogenetic placement and the monophyly of Pleostigmataceae lack statistical support, but the family was resolved as sister to the order Verrucariales. This family comprises the species Pleostigma alpinum sp. nov., P. frigidum sp. nov., P. jungermannicola, and P. lichenophilum sp. nov. The placement of the genus Melanina is supported as a lineage within the Chaetothyriales. To date, this genus comprises the single species M. gunde-cimermaniae sp. nov. and forms a sister group to a large lineage including Herpotrichiellaceae, Chaetothyriaceae, Cyphellophoraceae, and Trichomeriaceae. The new phylogenetic analysis of the subclass Chaetothyiomycetidae provides new insight into genus and family level delimitation and classification of this ecologically diverse group of fungi.

A comparison of methodological approaches to the subfamilial classification of the Naididae (Oligochaeta)

1987 ◽  
Vol 65 (3) ◽  
pp. 691-707 ◽  
Author(s):  
A. F. L. Nemec ◽  
R. O. Brinkhurst
Keyword(s):  
Data Matrix ◽  
Jaccard Coefficient ◽  
Data Set ◽  
Parsimony Method ◽  
Fit Statistics ◽  
Reconstruction Methods ◽  
Linkage Methods ◽  
The Family ◽  
First Time

A data matrix of 23 generic or subgeneric taxa versus 24 characters and a shorter matrix of 15 characters were analyzed by means of ordination, cluster analyses, parsimony, and compatibility methods (the last two of which are phylogenetic tree reconstruction methods) and the results were compared inter alia and with traditional methods. Various measures of fit for evaluating the parsimony methods were employed. There were few compatible characters in the data set, and much homoplasy, but most analyses separated a group based on Stylaria from the rest of the family, which could then be separated into four groups, recognized here for the first time as tribes (Naidini, Derini, Pristinini, and Chaetogastrini). There was less consistency of results within these groups. Modern methods produced results that do not conflict with traditional groupings. The Jaccard coefficient minimizes the significance of symplesiomorphy and complete linkage avoids chaining effects and corresponds to actual similarities, unlike single or average linkage methods, respectively. Ordination complements cluster analysis. The Wagner parsimony method was superior to the less flexible Camin–Sokal approach and produced better measure of fit statistics. All of the aforementioned methods contain areas susceptible to subjective decisions but, nevertheless, they lead to a complete disclosure of both the methods used and the assumptions made, and facilitate objective hypothesis testing rather than the presentation of conflicting phylogenies based on the different, undisclosed premises of manual approaches.

A revision of the subfamily Haplorchinae Looss, 1899 (Trematoda: Heterophyidae): I. The Haplorchis group

Parasitology ◽  
1964 ◽  
Vol 54 (4) ◽  
pp. 601-676 ◽  
Author(s):  
J. C. Pearson
Keyword(s):  
Life History ◽  
Ventral Sucker ◽  
Genital Pore ◽  
History Data ◽  
Life History Data ◽  
The Family ◽  
Excretory Bladder

Earlier schemes of classification of the family Heterophyidae have been based in large part on such features as shape of body, presence of oral spines, number and position of testes, and distribution of vitellaria (Witenberg, 1929; Ciurea, 1933; Mueller & Van Cleave, 1932). Price (1940a) was the first to make extensive use of features of the ventrogenital complex (ventral sucker, gonotyl, genital pore, terminal male duct) and excretory bladder, and produced the first reasonable classification of both the family Heterophyidae and the superfamily Opisthorchioidea. In despite of the obvious significance of the rationale of Price's approach, later authors (Morozov, 1952, 1955; Yamaguti, 1958) have largely ignored the ventrogenital complex and recently discovered life-history data, and have used much the same sorts of features as earlier authors.

scholarly journals I.—Notes on the Phylogeny of the Graptolites

1895 ◽  
Vol 2 (12) ◽  
pp. 529-539 ◽  
Author(s):  
H. A. Nicholson ◽  
J. E. Marr
Keyword(s):  
Present State ◽  
The Other ◽  
Other Hand ◽  
The Family ◽  
The Future ◽  
Geological Magazine

Since the remarkable paper by Professor Lapworth “On an Improved Classification of the Rhabdophora” was published in the Geological Magazine for 1873, a great deal of fresh information has been gathered as to these interesting fossils; but the classification given in that paper, though to some extent confessedly artificial, is still generally adhered to. Observations made by the authors in recent years lead them to suppose that that classification will in the future undergo considerable modification; but in the present state of our knowledge it serves a purpose so useful, that it is not our intention to propose any immediate change in it. Our object, on the other hand, is to bring forward certain conclusions which we have independently reached, and which will, we believe, enhance the value of Graptolites to the stratigraphical geologist, and lead to results important to the biologist. Our conclusions are based upon an examination of a large number of forms generally referred to the family Dichograptidæ; but, as we propose very briefly to indicate, they affect the relationships of Graptolites belonging to other families also.

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