DNA base composition and taxonomy of someAcinetobacter strains

The DNA base composition of a group of numerically analyzed acinetobacters was determined. Seven strains ofAcinetobacter anitratus appear to form a homogeneous group with S>90% and ca. 42.1 % GC.A. Iwoffii is less homogeneous. Most of the strains have around 46.6 % GC and a broad compositional distribution with 2=3.8 C. Two other small groups have a % GC of 44.8±0.3 and 42.1±1 % GC. The DNA characteristics of the latter group are indistinguishable fromA. anitratus-DNA. ThreeAlcaligenes faecalis strains have 58.8 % GC. Numerical analysis suggests that they might be related toBordetella bronchiseptica, but the % GC of the latter (69.5) shows that the relationship is only remote.     

Linking camera‐trap data to taxonomy: Identifying photographs of morphologically similar chipmunks

Remote cameras are a common method for surveying wildlife and recently have been promoted for implementing large‐scale regional biodiversity monitoring programs. The use of camera‐trap data depends on the correct identification of animals captured in the photographs, yet misidentification rates can be high, especially when morphologically similar species co‐occur, and this can lead to faulty inferences and hinder conservation efforts. Correct identification is dependent on diagnosable taxonomic characters, photograph quality, and the experience and training of the observer. However, keys rooted in taxonomy are rarely used for the identification of camera‐trap images and error rates are rarely assessed, even when morphologically similar species are present in the study area. We tested a method for ensuring high identification accuracy using two sympatric and morphologically similar chipmunk (Neotamias) species as a case study. We hypothesized that the identification accuracy would improve with use of the identification key and with observer training, resulting in higher levels of observer confidence and higher levels of agreement among observers. We developed an identification key and tested identification accuracy based on photographs of verified museum specimens. Our results supported predictions for each of these hypotheses. In addition, we validated the method in the field by comparing remote‐camera data with live‐trapping data. We recommend use of these methods to evaluate error rates and to exclude ambiguous records in camera‐trap datasets. We urge that ensuring correct and scientifically defensible species identifications is incumbent on researchers and should be incorporated into the camera‐trap workflow.     

Deoxyribonucleic acid base composition and taxonomy of violet-pigmented cocci

The content of guanine and cytosine in DNA of the violet-pigmented micrococci designated asStaphylococcus flavocyaneus andMicrococcus flavocyaneus varies within the range of 70.8 – 72.0%. These species have similar deoxyribonucleic acid base compositions and do not differ physiologically and morphologically: they both produce yellow and violet pigments, hydrolyse gelatin and casein, reduce nitrates and do not form lipase. Therefore we consider them in accordance with Kocur and Martinec (1962, 1963) identical. They do not, however, seem to be identical withMicrococcus luteus (Schroeter, 1872) Cohn 1872 because the content of guanine and cytosine in DNA of the neotype culture of this species was found to be 66.3%.Micrococcus luteus differs from the violet pigmented micrococci also physiologically. It does not produce violet pigment, does not hydrolyse gelatin and casein and does not produce urease. For the violet pigmented strainMicrococcus cyaneus the use of the original designation is recommended:Micrococcus cyaneus (Schroeter) Cohn 1872, as it differs from the other violet cocci not only physiologically — it does not produce yellow pigment, oxidises mannitol, dulcitol and sorbitol, produces lipase and does not hydrolyse casein — but also in its DNA base composition.     

Some applications of deoxyribonucleic acid base composition in bacterial taxonomy

The melting pointT _m, the mean molar (guanine+cytosine) composition and the compositional distribution of purified DNA from several strains ofXanthomonas, Chromobacterium and yellow-pigmented marine bacteria have been determined. These groups were selected because they had been analyzed adansonially. Ten strains ofXanthomonas had an average molar (guanine+cytosine) composition within the range 66.0–68.2%, which was very close to that ofPseudomonas (60–68%), as expected. All strains ofChromobacterium (six of theviolaceum biotype and three of thelividum biotype) had mean molar (guanine+cytosine) compositions within the range 63.4–71.4%. The yellow-pigmented marine flavobacteria had mean molar (guanine+cytosine) compositions of 35.6–40.6%. This suggests that they would not be genetically related to the yellow-pigmentedXanthomonas, nor to facultative aerobic organisms, such asAeromonas and theEnterobacteriaceae. The yellow-pigmented marine swarming bacteria, which resembleCytophaga, fell into two separate groups: some had a mean molar (guanine+cytosine) composition of about 34%, others were around 63%. This suggests genetic heterogeneity. The compositional distribution of DNA molecules was on the whole more narrow in polarly flagellated than in peritrichous organisms.     

Deoxyribonucleic acid base composition and taxonomy of Moniliella and allied genera

DNA base compositions of representative (type) strains of Moniliella, Trichosporonoides and Hyalodendron were determined. Within Trichosporonoides over 16% variance was found. Most species separated well, but M. suaveolens showed considerable heterogeneity. The standard 2% G+C differences for species distinction is probably not applicable to these yeasts. The new combination M. pollinis is proposed for M. tomentosa var. pollinis on the basis of slight ecological, morphological and physiological differences, supported by a marked difference in % G+C.     

Deoxyribonucleic acid base composition and taxonomy in the genus Geotrichum Link

The molar percentage of guanine + cytosine (% GC) in the DNA from 25 yeast-like fungi related to the genus Geotrichum has been measured. This criterion together with the biochemical characteristics allow the division of the species into 3 groups: one group resembling G. candidum (% GC: 31.5–42) and containing 8 imperfect and 6 perfect forms. In this group only G. capitatum has a lower % GC (31.5). A second group of 6 species resembling the genus Trichosporon (57–60%) and a third intermediate category of 4 species (42–53.5%) were observed. The GC-values correlate well with biochemical characters, e.g. the presence of urease, the number of organic substrates assimilated, and also with the presence of characters typical of the Ascomycetes or the Basidiomycetes.This work was supported by I.N.S.E.R.M. (Institut National de la Santé et de la Recherche Médicale) C.R.L. n^o 76 1 153 8.     

Compensatory changes in silver-stainability of nucleolar organizer regions in mice.

Silver-stainability of nucleolar organizer regions (NORs) that contain genes for ribosomal RNA (rDNA) was investigated using two mouse strains, BALB/cCrSlc and MOA, and their hybrid progeny. The patterns of segregation of the rDNA clusters were analyzed in terms of chromosomal C-banding and by use of a polymorphic probe for the variable region in backcrossed N2 and N3 individuals. The results indicate that the intensity of Ag-NOR staining is stably inherited in most of the rDNA clusters, irrespective of different genetic backgrounds. In some clusters, such as those on chromosome 12 of BALB/cCrSlc, a modulation of the intensity is observed. This modulation seems to be due to compensatory activation via a change in the number of actively transcribed genes. The change from silver-negative to silver-positive staining of the NOR of chromosome 12 of BALB/cCrSlc was correlated with demethylation of the genes.     

Bacillus brevis Migula 1900 taxonomy: reassociation and base composition of DNA.

Of 87 strains previously identified as Bacillus brevis Migula 1900, 58 had G + C contents of 47.0 to 51.9 mol%, a range that included the G + C content (48.7 mol%) of the type strain. The G + C contents for three other groups consisting of 5, 7, and 17 strains were 37.0 to 41.9, 42.0 to 46.9, and 52.0 mol% or higher, respectively. DNA reassociation studies showed that 25 of the 58 strains with G + C contents of 47.0 to 51.9 mol% were closely related genetically to the type strain and to each other. For the most part, this genetically related group was phenotypically homogeneous; variations in the fermentation of mannitol and mannose were observed. My results strongly suggest that many of the strains were misclassified as B. brevis. Consequently, much of the phenotypic heterogeneity of the species B. brevis Migula 1900 is not due to variations exhibited by genetically related organisms, but is the result of variability introduced by the presence of genetically unrelated strains.     

Compensatory changes in mammary development and function after hemimastectomy in lactating goats

Goats were hemimastectomized during Weeks 5 or 8 of lactation. The milk yield of the remaining gland (the test gland) usually increased in a compensatory fashion after the operation, although the degree of response varied from no response to a 50% increase. The glands of those goats that responded and received no further treatment maintained an increased milk yield for the duration of the lactation. Changes in the size and composition of the gland were investigated by a combination of udder volume and biopsy in some goats. Increases in both gross size and total DNA content (DNAt, a measure of cell number) were observed in all of these, although the timing of the response varied between individuals. Overall, cell population size was maintained for at least 18 weeks after hemimastectomy whereas in control (unoperated) goats DNAt decreased by 35% over a similar period.     

Compensatory changes in enzymes of arginine metabolism during renal hypertrophy in mice

The present study investigates enzyme activities of the urea cycle, transamidinase and ornithine–proline inter-conversion in the hypertrophied kidney after unilateral nephrectomy in mice. Surgical removal of the left kidney in mice led to compensatory enlargement of the right kidney after 1 and 14 days. This renal growth was associated with an increase in glomerular volume (but not number) and enlargement of the proximal convoluted tubules. The total renal protein content increased in proportion to the increase in kidney weight, but the protein per gram weight of kidney did not change. The specific activity of only ornithine aminotransferase (OAT), the rate-limiting enzyme in the conversion of ornithine to proline, increased in 2 weeks of hypertrophy. The specific activity of all other enzymes was unchanged. However, the total enzyme activity per kidney of all the enzymes, without exception, was elevated in the hypertrophied kidney. While the increase in total OAT activity was much more than the increase in kidney weight, all other enzymes increased more or less in proportion to the increase in renal mass. The results suggest that compensation in OAT activity to chronic reduction in renal mass was complete, but only partial in the case of other enzymes.