In vitro Effects of Prebiotics and Synbiotics on Apis cerana Gut Microbiota

This study aimed to investigate in vitro effects of the selected prebiotics alone, and in combination with two potential probiotic Lactobacillus strains on the microbial composition of Apis cerana gut microbiota and acid production. Four prebiotics, inulin, fructo-oligosaccharides, xylo-oligosaccharides, and isomalto-oligosaccharides were chosen, and glucose served as the carbon source. Supplementation of this four prebiotics increased numbers of Bifidobacterium and lactic acid bacteria while decreasing the pH value of in vitro fermentation broth inoculated with A. cerana gut microbiota compared to glucose. Then, two potential probiotics derived from A. cerana gut at different dosages, Lactobacillus helveticus KM7 and Limosilactobacillus reuteri LP4 were added with isomalto-oligosaccharides in fermentation broth inoculated with A. cerana gut microbiota, respectively. The most pronounced impact was observed with isomalto-oligosaccharides. Compared to isomalto-oligosaccharides alone, the combination of isomalto-oligosaccharides with both lactobacilli strains induced the growth of Bifidobacterium, LAB, and total bacteria and reduced the proliferation of Enterococcus and fungi. Consistent with these results, the altered metabolic activity was observed as lowered pH in in vitro culture of gut microbiota supplemented with isomalto-oligosaccharides and lactobacilli strains. The symbiotic impact varied with the types and concentration of Lactobacillus strains and fermentation time. The more effective ability was observed with IMO combined with L. helveticus KM7. These results suggested that isomalto-oligosaccharides could be a potential prebiotic and symbiotic with certain lactobacilli strains on A. cerana gut microbiota.     

Intertidal zonation of prosobranch gastropods: Analysis of densities of four co-existing species

The densities of populations of Nerita atramentosa Reeve, Austrocochlea constricta Lamarck, Bembiciuin nanum (Lamarck), and Cellana tramoserica (Sowerby) were recorded in 0.25 m² quadrats on landward and seaward halves of a sheltered and a moderately exposed rock platform from June 1972 to June 1973. The data have been subjected to variance and multiple regression analysis. Differences between densities of each species on the two shores and in the two areas of each shore are discussed with respect to the regressions on littoral height. Densities of Nerita on the sheltered shore, Austrocochlea and Bembicium on both shores, and Cellana, on the exposed shore, increased with height. The density of Cellana on the sheltered shore decreased as height increased. The density differences in the landward and seaward areas on the two shores were attributable to the effect of height for Nerita and Austrocochlea. Height was the major variable affecting the density of these two species on the sheltered shore. Bembicium and Cellana densities on both shores, and Austrocochlea density on the exposed shore, are not primarily determined by height.On the sheltered shore, Nerita and Cellana increased in density with increasing cover of water in rock pools. On the exposed shore, Bembicium and Cellana became sparser with increasing water cover. Bembicium on both shores increased in density with increasing cover of the alga Peyssonelia, as did Cellana on the exposed shore. Cellana and Austrocochlea tended to increase in density with Nerita on the sheltered shore. Cellana tended to be sparse where Bembicium was dense on the exposed shore. The biological effects of substrata and other species on the densities of each species remain unexplained.Significant time effects were found for variations in the densities of Nerita and Cellana on the sheltered shore and of Austrocochlea and Cellana on the exposed shore. The seasonal change in density of Nerita was parabolic with a minimum in summer, and is consistent with the known period of recruitment of this species. The lack of significant time effects on density of Austrocochlea on the sheltered shore is consistent with the known continuous recruitment of this species. The declining density of Austrocochlea on the moderately exposed shore was found, by size-frequency analysis, to be due to reduced recruitment compared with surrounding shores. The density of Cellana on both shores showed seasonal changes, with a maximum in summer, which is consistent with the known period of recruitment in Cellana. The lack of seasonal changes in density of Bembicium is briefly discussed.This type of multifactor analysis identifies biological interactions affecting variation in density of these species. It also corroborates the results of other ecological investigations and determines the relative importance of a variety of physical and biological factors in the distribution of density of intertidal gastropods.     

Synthesis of 3-O-acyl esters of serine and threonine

The 3-O-acyl derivatives of serine and threonine have been prepared by reacting oleoyl chloride and palmitoyl chloride with N-t-butoxycarbonyl (N-T-BOC) serine and N-t-BOC threonine. The t-BOC group was removed by treatment with 4 N HCl in dioxane. The products were identified by proton magnetic resonance spectroscopy, infrared spectroscopy, elemental analysis and chromatographic properties. The O-acyl serines and O-acyl threonines were converted to their methyl esters by treatment with boron trifluoride in methanol and were converted to their dinitrophyl derivatives by treatment with dinitrofluorobenzen (DNFB). The yield of the dinitrophenyl derivatives was very high but the yield of methyl esters was low due mainly to methanolysis and loss of the fatty acyl group. The O-acyl serines and O-acyld threonines prepared will provide standards for researchers who are interested in identifying fatty acids esterified to serine and threonine hydroxyl groups in membrane proteins.     

Distance of the reduced Brusselator from equilibrium

The new concept of a nonequilibrium parameter P is applied to a reduced Brusselator, considered as a kinetic model for cellular processes. The reduction corresponds to omitting a monomolecular reaction. The deviation from equilibrium is due to a fixed nonequilibrium value of an extracellular concentration B, responsible for energizing and determining the steady-state value of the overall chemical affinity ?. The value of ? is insensitive to different steady states possible for a given set of rate constants. In contrast, the parameter P is state dependent. In particular, it may jump together with state variables. Two limiting cases of high ? are investigated, B→ 0 and B→ 1. In the first case P grows monotonically with ?. In the second case there is always a steady state solution with P→ 0. The physical interpretation of this effect of “equilibrium far from equilibrium” reveals the real predictive power of the parameter P. Relaxation regimes are investigated for a doubly reduced Brusselator. Both P and ? are in general time dependent and have jumps in their time derivatives. The canonical form of P is compared with the noncanonical one in the context of robustness of the new concept with respect to incomplete information about the system studied. These forms of P are different in relaxation to a nonequilibrium state and coincide in relaxation to an equilibrium state.     

Two aberrant mercury resistance transposons in the Pseudomonas stutzeri plasmid pPB

The two mer operons of the Pseudomonas stutzeri OX plasmid pPB and their flanking regions have been sequenced and found to be part of two aberrant transposons. The narrow spectrum mer operon is almost identical to that of Tn501, but is associated with the remnants of Tn5053 tni genes rather than the Tn501 transposition module. The broad spectrum mer operon shows an overall homology with that of Tn5053, but differs from it in the presence of a merB gene, absent in Tn5053, and a merC gene instead of a merF. The pPB broad spectrum mer operon is associated with an incomplete Tn5053-like transposition module and with the Tn501 tnp genes, which are proximal, respectively, to the end and to the beginning of the mer operon. A hypothesis about pPB evolution is presented.     

Studies on the specificity of killing of intracellular pathogens by macrophages.

To determine whether macrophages can discriminate in an immunologically specific manner between the intracellular pathogens which they inhibit or kill, unelicited peritoneal macrophages from mice infected with either of two related but antigenically dissimilar protozoa were challenged with these protozoa in vitro. Experimental conditions were varied in an attempt to establish a state in vivo in which macrophage specificity might be demonstrated. No differences could be discerned between the ability of macrophages from three different strains of mice infected with the protozoa to kill Besnoitia and Toxoplasma. The effect of macrophages on Toxoplasma as compared with Besnoitia did not evolve or vary during development, expression, or decline of an immune response, i.e., with varying times after infection of mice as well as with varying times after treatment of mice with irradiated Toxoplasma. The route of infection could not be shown to confer specificity on macrophages, as subcutaneous and intraperitoneal inoculation of Toxoplasma did not lead to differential ability of macrophages to inhibit or kill the protozoa. The different strains of protozoa used for infection of mice did not affect the ability of peritoneal macrophages from Besnoitia- and Toxoplasma-infected mice to inhibit multiplication of or kill Besnoitia and Toxoplasma comparably in vitro. Peritoneal macrophages of mice treated with Corynebacterium parvum kill both organisms efficiently. These macrophages were employed to determine whether stimulation of macrophages by treatment of mice with a substance unrelated to the protozoa would produce activated macrophages. Uninfected mice and mice infected with either Besnoitia or Toxoplasma were challenged with varying doses of the protozoa in parallel with examination of macrophages from the same groups of mice in vitro to determine whether the presence of stimulated macrophages in the peritoneal cavity was necessary for protection against Toxoplasma and Besnoitia, and if so if their presence was sufficient for protection. Only mice with activated peritoneal macrophages were protected. However, protection was greater when the primary infection was with the same organisms used for challenge at a time when macrophages inhibited or killed both protozoa efficiently in vitro. The possible role of other effector cells, subpopulations of macrophages of different functional abilities in various sites, and antibody or other lymphocyte products acting in concert with macrophages as factors which may explain the differences observed between in vivo protection and in vitro capacity to inhibit or kill the protozoa are discussed.     

Reaction of cytochrome c in the electron-transport chain of Paracoccus denitrificans

The reaction of the cytochrome c oxidase (ferrocytochrome c:oxygen oxidoreductase, EC 1.9.3.1) of Paracoccus denitrificans cytoplasmic membranes with the endogenous cytochrome c of the membranes was studied, as well as its interaction with added exogenous cytochrome c from P. denitrificans or bovine heart. The polarographic method was employed, using N,N,N′,N′-tetramethyl-p-phenylenediamine plus ascorbate to reduce the cytochrome c. We found that overall electron transport can proceed maximally while the cytochrome c remains membrane bound; NADH or succinoxidase activities were not inhibited by the addition of substances which bind the P. denitrificans cytochrome c strongly. In contrast to our observations with the spectrophotometric method (Smith, L., Davies, H.C. and Nava, M.E. (1976) Biochemistry 15, 5827–5831), in the polarographic assays the membrane-bound oxidase reacts with about equal rapidity with exogenous bovine and P. denitrificans cytochromes c. The reaction of the oxidase with the endogenous cytochrome c proceeds at high rates and preferentially to that with exogenous cytochrome c; the reaction with the latter, but not the former is inhibited by positively charged poly(l-lysine). The cytochrome c and the oxidase appear to be very closely associated on the membrane.     

Geographical variation in Fennoscandian and Estonian Schoenus wetlands

Using TABORD five Schoenus ferrugineus associations have been distinguished from the literature. They are well distinguished by differential-species combinations and most of them are described earlier under identical names, e.g., the Primula-, Oxycoccus-, Myrica-, and Trichophorum-Schoenus ferrugineus ass. The Thalictrum-Schoenus ferrugineus ass. is a new syntaxon. They are further characterized by different floristic elements according to their geographical distribution. The Primula-Schoenus ferrugineus ass. is related to Central Europe, the Primulo-Schoenetum ferruginei from Oberd. (1957) 1962. All other associations discussed have no counterparts elsewhere in Europe. The shortcoming of this classification and the impossibility of a syntaxonomical ranking are emphasized. The variation in species composition and site conditions is elucidated by RA ordination. A complex soil moisture gradient is related to the differences in species composition between the Primula-, Oxycoccus-, and Myrica-Schoenus ferrugineus ass. Wet topogenous mire sites with peat formation and a rather low pH is typical of the Myrica-Schoenus ferrugineus ass., while the Primula-Schoenus ferrugineus ass. occurs either in moist soligenous mire sites or in to pogenous sites with strongly shifting water tables and with muck (Anmoor) instead of peat. The site conditions of the Oxycoccus-Schoenus ferrugineus ass. are most similar to those of the Myrica-Schoenus ferrugineus ass. The Trichophorum- and Thalictrum-Schoenus ferrugineus ass. occur on soligenous mire sites.     

Fine structure of body wall cuticle of females of Meloidodera charis,Atalodera lonicerae,and Sarisodera hydrophila (Heteroderidae)

The body wall cuticle of adult females of Meloidodera charis, Atolodera lonicerae, and Sarisodera hydrophila is examined by transmission electron and light microscopy for comparison with Heterodera schachtii and previous observations of additional species of Heterodera, Globodera, and Punctodera. The cuticle of M. charis is least complex, consisting of layers A, B, C (with A outermost), and varies in overall thickness from 3 to 8 μm. As in other species, the cuticle is thickest in mature specimens. The cuticle of A. lonicerae is 6-9 μm thick; unlike M. charis it has an innermost layer, D, in addition to A, B, and C. The cuticle of S. hydrophila varies from 14 to 30 μm thick and includes a D layer similar to A. lonicerae; layer C is subdivided into additional zones relative to other heteroderids, and the external portion of the cuticle is infused with an electron-dense material. The presence of a D layer in A. lonicerae and S. hydrophila is a character state which is shared with Globodera spp. and Punctodera sp. The electron-dense material in the outer layers of S. hydrophila also occurs in Globodera spp. and Punctodera sp. On the other hand, H. schachtii resembles other Heterodera spp. as well as M. charis by the absence of a D layer and lack of electron-dense material in the outer layers. The pattern of occurrence of shared character states, including those of the cuticle, may be useful for phylogenetic analysis of Heteroderidae.     

Porphyromonas gingivalis,Aggregatibacter actinomycetemcomitans,and Treponema denticola / Prevotella intermedia Co-Infection Are Associated with Severe Periodontitis in a Thai Population

Periodontitis is a polymicrobial infection of tooth-supporting tissues. This cross-sectional study aimed to examine the associations between five target species and severe periodontitis in a Thai population. Using the CDC/AAP case definition, individuals diagnosed with no/mild and severe periodontitis were included. Quantitative analyses of Aggregatibacter actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), Tannerella forsythia (Tf), Treponema denticola (Td), and Prevotella intermedia (Pi) in subgingival plaque were performed using real-time polymerase chain reaction. The association between target species and severe periodontitis was examined using logistic regression analysis. The study subjects comprised 479 individuals with no/mild periodontitis and 883 with severe periodontitis. Bacterial prevalence and quantity were higher in subjects with severe periodontitis than in those with no/mild disease. In the fully adjusted model, all species except Tf showed a dose-dependent relationship with periodontitis. The mere presence of Pg, even in low amount, was significantly associated with severe periodontitis, while the amount of Aa, Td, and Pi had to reach the critical thresholds to be significantly associated with disease. Compared to individuals with low levels of both Td and Pi, high colonization by either Td or Pi alone significantly increased the odds of having severe periodontitis by 2.5 (95%CI 1.7–3.5) folds. The odds ratio was further increased to 14.8 (95%CI 9.2–23.8) in individuals who were highly colonized by both species. Moreover, the presence of Pg and high colonization by Aa were independently associated with severe periodontitis with odds ratios of 5.6 (95%CI 3.4–9.1) and 2.2 (95%CI 1.5–3.3), respectively. Our findings suggest that the presence of Pg and high colonization by Aa, Td, and Pi play an important role in severe periodontitis in this study population. We also demonstrate for the first time that individuals co-infected with Td and Pi were more likely to have periodontitis than were those infected with a single pathogen.     

湘中丘陵区南酸枣阔叶林群落特征及群落更新

南酸枣阔叶林群落是湘中丘陵区的重要的森林群落类型之一,在森林演替过程中占有重要的地位。在湘中丘陵区长沙县大山冲林场的代表性群落——南酸枣阔叶林群落(The Choerospondias axillaries broad-leaved community)设立1 hm2固定样地,对其群落学特征进行调查,分析其植物多样性和更新动态。结果表明:群落中胸径≥1cm的乔木树种共有25科42属59种。乔木层中南酸枣(Choerospondias axillaries)的重要值最大(23.57),是群落中的建群种;南酸枣胸径和树高结构均呈正态分布,南酸枣幼苗(1.0cm≤DBH1.5cm)只有6株;群落中四川山矾(Symplocos setchuensis)的重要值(10.46)排第二,但胸径小于1.5 cm的幼树数量较多(占种群数量的22.0%),格药柃(Eurya muricata)、千年桐(Aleurites montana)和毛豹皮樟(Lindera coreana)的重要值分别为7.98(幼树数占种群数量的16.8%),5.39(幼树数占种群数量的11.7%),4.17(幼树数占种群数量的11.0%),这4个乔木树种的径级结构均呈倒J型分布;林分的成层结构中,上层木主要为南酸枣,下层木主要为四川山矾、格药柃、千年桐和毛豹皮樟。林下幼苗主要为常绿阔叶树种,且更新良好,并将成为下一个演替阶段的建群种。南酸枣的幼苗更新不良情况说明其在群落中的优势地位在逐年降低,而四川山矾、格药柃、千年桐、毛豹皮樟等树种的优势地位呈上升趋势,表明湘中丘陵区的南酸枣阔叶林群落正在朝常绿阔叶林的方向演替。灌木、草本层中共有植物37种,重要值前5位的种为檵木(Loropetalum chinensis)、满山红(Rhododendron mariesii)、乌饭(Vaccinium bracteatum)、栀子(Gardenia jasminoides)、映山红(Rhododendron simsii)分别为54.59、21.85、4.98、4.63、4.53,其中,檵木和满山红在灌木层中的优势地位明显。     

Some heterostrophic gastropods from Triassic St. Cassian Formation with a discussion on the classification of the Allogastropoda

Fifteen species of Heterostropha are described, 12 of them for the first time. All are newly interpreted with regard to their taxonomic relation to fossil and living gastropods. The Streptacidoidea with long Paleozoic history are represented in the Late Triassic St. Cassian Formation by several genera that can be differentiated into four families. The Ebalidae are represented byEbala, with smooth protoconch, Cassianebalidae byCassianebala andLoxebala with axially ornamented protoconch. The Donaldinidae of St. Cassian are represented by one species ofDonaldina and two ofNeodonaldina that stand in the continuation of Paleozoic species ofDonaldina. Architectonicoidea with shells coiled in a plane and Valvatoidea appear in the St. Cassian fauna without known Paleozoic relation. In the former superfamily the Architectonicidae can be recognized in the genusRinaldoconchus with two species. Cassianaxidae withCassianaxis, Amphitomariidae withAmphitomaria, Stuoraxidae withStuoraxis andAmpezzogyra have a sinistral protoconch and planispirally coiled dextral teleconchs. They all resemble different modern species that have similarly small shells. Modern Hyalogyrinidae have withAlexogyra a new representative from the Triassic. The Valvatoidea are represented with the generaCarboninia andBandellina of the Cornirostridae in the Triassic representatives. The relation of described species in the system of the Heterostropha is discussed.     

Reassessment of Paleotachina Townsend and Electrotachina Townsend and their removal from?the?Tachinidae (Diptera)

The monotypic genera Paleotachina Townsend, 1921 and Electrotachina Townsend, 1938 were originally described as fossils in amber but were later discovered to be inclusions in copal. Both taxa were originally assigned to the Tachinidae (Diptera) and this placement has continued to the present day. The holotypes of the two type species, P. smithii Townsend and E. smithii Townsend, were examined and the following taxonomic and nomenclatural changes are proposed: Paleotachina is transferred to the Muscidae and placed in synonymy with Aethiopomyia Malloch, 1921, syn. n.; P. smithii Townsend, type species of Paleotachina, is synonymized with Aethiopomyia gigas (Stein, 1906), syn. n.; Electrotachina is transferred to the Sarcophagidae and placed in synonymy with Dolichotachina Villeneuve, 1913, syn. n.; E. smithii Townsend, type species of Electrotachina, is recognized as a valid species of Dolichotachina comb. n. Images of the holotypes of P. smithii and E. smithii are provided and features that have helped place these copal inclusions in their new combinations are discussed.     

Construction and Analysis of a Streptococcus parasanguis recA Mutant: Homologous Recombination Is Not Required for Adhesion in an In Vitro Tooth Surface Model

PCR was used to amplify an internal region of the recA gene from Streptococcus parasanguis FW213. The PCR fragment was used as a probe to recover the entire streptococcal recA gene from an S. parasanguis genomic library, and the sequence of the gene was determined. The deduced product of the S. parasanguis recA gene showed a high degree of amino acid identity with other prokaryotic RecA proteins. The cloned recA sequence was disrupted in vitro by insertional mutagenesis, and the mutated allele was then introduced into the S. parasanguis chromosome by homologous recombination. Results of Southern hybridizations confirmed the replacement of the wild-type recA gene with the mutated allele. The recA mutant strain was considerably more sensitive to UV light than the parental strain, and this phenotype was consistent with a mutation in recA. The S. parasanguis recA mutant showed no reduction in its ability to adhere in the in vitro tooth surface model, saliva-coated hydroxylapatite (SHA), or in its ability to express the fimbria-associated adhesin Fap1. These results demonstrate that in vitro attachment of S. parasanguis FW213 to SHA and expression of Fap1 are recA independent.     

Host Response to Meloidodera spp. (Heteroderidae)

Host responses to Meloidodera floridensis Chitwood et al., 1956, M. charis Hooper, 1960, and M. belli Wouts, 1973 were examined on loblolly pine, peony, and sage, respectively, with light, scanning, and transmission electron microscopy. In each case the nematodes induce a single uninucleate giant cell. The giant cell is initiated in the pericycle and expands as it matures. The mature giant cell induced by M. floridensis is surrounded by vascular parenchyma, whereas that caused by M. charts and M. belli coutacts xylem and phloem. The cell wall of giant cells induced by all three Meloidodera spp. is generally thicker than that of surrounding cells, with the thickest part adjacent to the lip region of the nematode. The thinner portion of the wall includes numerous pit fields with plasmodesmata, but wall ingrowths were not detected in a thorough examination of the entire wall. The nucleus of a giant cell induced by M. goridensis is highly irregular in shape with deep invaginations, whereas those caused by M. charis and M. belli include a cluster of apparently interconnected nuclear units. Organelles, including mitochondria, endoplasmic reticulum, and plastids of giant cells caused by Meloidodera, are typical of those reported in host responses of other Heteroderidae. The formation of a single uninucleate giant cell by Meloidodera, Cryphodera, Hylonerna, and Sarisodera, but a syncytium by Atalodera and Heterodera sensu lato, might be considered in conjunction with additional characters to determine the most parsimonious pattern of phylogeny of Heteroderidae.     

A new type of UV-sensitive mutant of phage T4D

Within a group of more than 20 UV-sensitive mutants of T4D, 4 UV-sensitive mutants with the same sensitivity as T4 x were isolated independently of each other. They were uvs9, uvs21, uvs35, and uvs52. The double mutants with x and y₁₀ were constructed: they are slightly more UV sensitive than T4 v₁. The double mutant with uvs5 was not found. The mutations of uvs9, 21, 35, and 52 are closely linked with v₁. The photoreactivable sector (PRS) is 0.4. One of the mutants, uvs52, has the same sensitivity for methyl methanesulphonate (MMS) as T4⁺, shows a stronger multiplicity reactivation than the wild type, shows the same sensitivity relative to T4⁺ and T4 v₁ in Luria-Latarjet tests and in monocomplex UV inactivation, and raises the recombinant frequency in crosses with irradiated phage. The uvs52⁺ function has the same sensitivity to UV as the v⁺ function. Complementation between uvs52 and v₁, if present is difficult to demonstrate owing to an appreciable MR contribution to increased survival. The possibility that uvs52 is an allele of v₁ is discussed. The observations fit the assumption that uvs52 is an excision-repair mutant with a low excision rate.     

Molecular identification and phylogenetic analysis of Aloe shadensis from Saudi Arabia based on matK,rbcL and ITS DNA barcode sequence

The Kingdom of Saudi Arabia thrives with great plant diversity, including rare plants of the family Asphodelaceae that have multiple benefits and are still being studied. Aloe shadensis is one of these plants that must be preserved and documented in its natural environment. The most appropriate molecular approach currently approved for documentation is the sequencing of some genomic markers. The current study is the first to use genomic markers to record this rare plant. In this study, the plastid genes matK (Maturase K), rbcL (Ribulose-bisphosphate carboxylase/oxygenase large subunit), and the nuclear region ITS (Internal transcribed spacer) were used to reveal their efficiency in identifying the plant under study. This study is the first to deal with this plant and document it using these genetic markers. The study showed a promising result concerning identifying the sequence of the matK gene and ITS region, while the rbcL gene did not give a good indicator through the used primers. The obtained sequences of the matK gene and the ITS region were determined through two different sets of primers in each case then deposited in GenBank. The evolutionary relatedness of Aloe shadensis was established with the different species of Aloe. The study showed that the closest species is Aloe vera with a similarity of more than 99 %. The study concludes with the possibility of using these genes to correctly identify, distinguish and document the species of Aloe shadensis.     

Phaseolus vulgaris is nodulated by the symbiovar viciae of several genospecies of Rhizobium laguerreae complex in a Spanish region where Lens culinaris is the traditionally cultivated legume

Phaseolus vulgaris and Lens culinaris are two legumes with different distribution centers that were introduced in Spain at different times, but in some regions L. culinaris has been traditionally cultivated and P. vulgaris did not. Here we analysed the rhizobia isolated from nodules of these two legumes in one of these regions. MALDI-TOF MS analysis showed that all isolated strains matched with Rhizobium laguerreae and the phylogenetic analysis of rrs, atpD and recA genes confirmed these results. The phylogenetic analysis of these core genes allowed the differentiation of several groups within R. laguerreae and unexpectedly, strains with housekeeping genes identical to that of the type strain of R. laguerreae presented some differences in the rrs gene. In some strains this gene contains an intervening sequence (IVS) identical to that found in Rhizobium strains nodulating several legumes in different geographical locations. The atpD, recA and nodC genes of all isolated strains clustered with those of strains nodulating L. culinaris in its distribution centers, but not with those nodulating P. vulgaris in theirs. Therefore, all these strains belong to the symbiovar viciae, including those isolated from P. vulgaris, which in the studied region established effective symbiosis with the common endosymbiont of L. culinaris, instead to with its common endosymbiont, the symbiovar phaseoli. These results are particularly interesting for biogeography studies, because they showed that, due its high promiscuity degree, P. vulgaris is able to establish symbiosis with local symbiovars well established in the soil after centuries of cultivation with other legumes.     

Proteolytic susceptibility of food by-product proteins: An evaluation by means of a quantitative index

A proteolytic susceptibility index was proposed to evaluate the reaction performance of different food by-products with subtilisin. Whey, salmon muscle and feather keratine were hydrolyzed at the same peptide bond concentration at 50 °C and pH 8.0 with different subtilisin concentrations. The logarithmic equation P = 1/b ln(abt+1) was fitted to estimate the kinetic constants a and b. The a/b ratio was proposed as a proteolytic susceptibility index, which was correlated with the chemical structure and conformation of protein sources in increasing order of feather keratin, salmon muscle and whey proteins with corresponding a/b values of 0.1, 8.2 and 14.4 mM²/min, respectively. The methodology proposed in this work can be used to evaluate the proteolytic susceptibility of different protein by-products to different proteases and to evaluate the changes in proteolytic susceptibility after treatment.