[Argentine registry of office blood pressure monitoring. RAMPAC study]

INTRODUCTION

Hypertension (HTN) is the leading cause of mortality and disability in the world. In Argentina, almost 44% of hypertensives do not know about their condition and this may be due to the low rate of blood pressure (BP) measurements during the office visit. Our hypothesis is that the measurement and electronic recording of BP (BPMR) is not a routine practice in Argentina.

OBJECTIVE

To describe the rate of office BP measurement in Argentina.

METHODS

This is a retrospective, multicentre, point prevalence study. We analysed all office visits on 9/19/2019 at 9 medical institutions in 6 provinces of Argentina.

RESULTS

Two thousand and eighty-two office visits were analysed. The patients' mean age was 52.1 years (18-103), 1790 (59.7%) were female, and 702 (36.1%) were hypertensives. BP was measured in 420 visits (14.1%; 95% CI 12.8-15.4). In a multivariate logistic regression model, history of HTN (OR 1.91, P<.001) and previous cardiovascular event (OR 1.76, P<.001) were associated with more odds of BPMR. The presence of cancer was associated with fewer odds of BPMR (OR .51, P<.01). Cardiology measured BP up to 49.5% (144/291 visits), followed by internal medicine 30% (152/507 visits).

CONCLUSION

BPMR during office visits is deficient in Argentina and represents a missed healthcare opportunity. Different strategies are needed to detect hypertensive patients and reduce cardiovascular events.

Photosynthesis and mineralogy of Jania rubens at low pH/high pCO2: A future perspective

Corallinales (Rhodophyta) are high Mg-calcite macroalgae and are considered among the most vulnerable organisms to ocean acidification (OA). These sensitive species play fundamental roles in coastal systems as food source and settlement promoters as well as being involved in reef stabilization, and water carbonate balance. At present only a few studies are focused on erect calcifying macroalgae under low pH/high pCO₂ and the contrasting results make difficult to predict the ecological consequences of the OA on the coralline algae. In this paper the physiological reasons behind the resistance of Jania rubens, one of the most common calcareous species, to changing ocean pH are analysed. In particular, we studied the photosynthetic and mineralogical response of J. rubens after a three-week transplant in a natural CO₂ vent system. The overall results showed that J. rubens could be able to survive under predicted pH conditions even though with a reduced fitness; nevertheless physiological limits prevent the growth and survival of the species at pH6.7. At low pH (i.e. pH7.5), the maximum and effective PSII efficiency decreased even if the increase of Rubisco expression suggests a compensation effort of the species to cope with the decreased light-driven products. In these circumstances, a pH-driven bleaching phenomenon was also observed. Even though the photosynthesis decreased at low pH, J. rubens maintained unchanged the mineralogical composition and the carbonate content in the cell wall, suggesting that the calcification process may also have a physiological relevance in addition to a structural and/or a protective role. Further studies will confirm the hypotheses on the functional and evolutionary role of the calcification process in coralline algae and on the ecological consequences of the community composition changes under high pCO₂ oceans.

Remote memories are enhanced by COMT activity through dysregulation of the endocannabinoid system in the prefrontal cortex

The prefrontal cortex (PFC) is a crucial hub for the flexible modulation of recent memories (executive functions) as well as for the stable organization of remote memories. Dopamine in the PFC is implicated in both these processes and genetic variants affecting its neurotransmission might control the unique balance between cognitive stability and flexibility present in each individual. Functional genetic variants in the catechol-O-methyltransferase (COMT) gene result in a different catabolism of dopamine in the PFC. However, despite the established role played by COMT genetic variation in executive functions, its impact on remote memory formation and recall is still poorly explored. Here we report that transgenic mice overexpressing the human COMT-Val gene (COMT-Val-tg) present exaggerated remote memories (>50 days) while having unaltered recent memories (<24 h). COMT selectively and reversibly modulated the recall of remote memories as silencing COMT Val overexpression starting from 30 days after the initial aversive conditioning normalized remote memories. COMT genetic overactivity produced a selective overdrive of the endocannabinoid system within the PFC, but not in the striatum and hippocampus, which was associated with enhanced remote memories. Indeed, acute pharmacological blockade of CB1 receptors was sufficient to rescue the altered remote memory recall in COMT-Val-tg mice and increased PFC dopamine levels. These results demonstrate that COMT genetic variations modulate the retrieval of remote memories through the dysregulation of the endocannabinoid system in the PFC.

Involvement of cell surface TG2 in the aggregation of K562 cells triggered by gluten

Gluten-induced aggregation of K562 cells represents an in vitro model reproducing the early steps occurring in the small bowel of celiac patients exposed to gliadin. Despite the clear involvement of TG2 in the activation of the antigen-presenting cells, it is not yet clear in which compartment it occurs. Herein we study the calcium-dependent aggregation of these cells, using either cell-permeable or cell-impermeable TG2 inhibitors. Gluten induces efficient aggregation when calcium is absent in the extracellular environment, while TG2 inhibitors do not restore the full aggregating potential of gluten in the presence of calcium. These findings suggest that TG2 activity is not essential in the cellular aggregation mechanism. We demonstrate that gluten contacts the cells and provokes their aggregation through a mechanism involving the A-gliadin peptide 31-43. This peptide also activates the cell surface associated extracellular TG2 in the absence of calcium. Using a bioinformatics approach, we identify the possible docking sites of this peptide on the open and closed TG2 structures. Peptide docks with the closed TG2 structure near to the GTP/GDP site, by establishing molecular interactions with the same amino acids involved in stabilization of GTP binding. We suggest that it may occur through the displacement of GTP, switching the TG2 structure from the closed to the active open conformation. Furthermore, docking analysis shows peptide binding with the β-sandwich domain of the closed TG2 structure, suggesting that this region could be responsible for the different aggregating effects of gluten shown in the presence or absence of calcium. We deduce from these data a possible mechanism of action by which gluten makes contact with the cell surface, which could have possible implications in the celiac disease onset.

The empirical discovery of phylogenetic invariants

An invariant Φ of a tree T under a k-state Markov model, where the time parameter is identified with the edges of T, allows us to recognize whether data on N observed species can be associated with the N terminal vertices of T in the sense of having been generated on T rather than on any other tree with N terminals. The invariance is with respect to the (time) lengths associated with the edges of the tree. We propose a general method of finding invariants of a parametrized functional form. It involves calculating the probability f of all kN data possibilities for each of m edge-length configurations of T, then solving for the parameters using the m equations of form Φ (f) = 0. We apply this to the case of quadratic invariants for unrooted binary trees with four terminals, for all k, using the Jukes–Cantor type of Markov matrix. We report partial results on finding the smallest algebraically independent set of invariants.

Muc5ac mucin expression during rat skin development

Some mucin genes have been detected during human embryonic and fetal organ development; however, little is known about mucin expression in epidermal development, neither in humans nor in other species. The present research was developed to explore Muc5ac skin expression during pre- and post-natal rat development. Immunohistochemistry (IHC), Western blotting (WB) and RT-PCR were employed. By IHC, Muc5ac protein was found early in embryonic epidermis from day 13 of gestation until seven days after birth when the surface epidermis became negative and the reaction was restricted to secreting sebum cells. In coincidence with IHC findings, WB analysis showed a band at approximately 200KDa at the same periods of development. Results were also confirmed by RT-PCR.

Muc5ac expression in rat embryonic epidermis suggests that Muc5ac may play a protective role in embryonic skin previous to birth which may be replaced by pile covering. To our knowledge, this is the first report that confirmed Muc5ac expression during skin development.

Securing the data economy: translating privacy and enacting security in the development of DataSHIELD

Contemporary bioscience is seeing the emergence of a new data economy: with data as its fundamental unit of exchange. While sharing data within this new 'economy' provides many potential advantages, the sharing of individual data raises important social and ethical concerns. We examine ongoing development of one technology, DataSHIELD, which appears to elide privacy concerns about sharing data by enabling shared analysis while not actually sharing any individual-level data. We combine presentation of the development of DataSHIELD with presentation of an ethnographic study of a workshop to test the technology. DataSHIELD produced an application of the norm of privacy that was practical, flexible and operationalizable in researchers' everyday activities, and one which fulfilled the requirements of ethics committees. We demonstrated that an analysis run via DataSHIELD could precisely replicate results produced by a standard analysis where all data are physically pooled and analyzed together. In developing DataSHIELD, the ethical concept of privacy was transformed into an issue of security. Development of DataSHIELD was based on social practices as well as scientific and ethical motivations. Therefore, the 'success' of DataSHIELD would, likewise, be dependent on more than just the mathematics and the security of the technology.

Navigating the perfect [data] storm

Bioscience has recently undergone a series of knowledge-based and technological revolutions. A critical consequence has been increasing recognition of the need to invest in infrastructure. Good access to data (and samples) from multiple studies is axiomatic to the value of this infrastructure. Access must be streamlined, secure, and based upon transparent and ‘fair’ decision making. It must be clear who has created and who has used which data. Ethico-legal policies and guidelines, which reflect dominant local cultural and societal norms, must take account of the increasingly global nature of bioscience research. A robust data infrastructure must also be attentive to the translational aims and social impact of its knowledge generation. In order to maintain the trust of its constituency – the general public as well as professional, political, commercial stakeholders – it must develop mechanisms to take account of all of these perspectives. These considerations form the basis of an emerging data economy. Building on extant achievements and pursuing the ideas outlined here could revolutionise the way we use and manage large-scale data. They have critical implications for biomedical and public health research communities and will be of central relevance for healthcare managers and policy makers, governments and industry. However, if the major challenges are to be met we must continue to invest,both nationally and internationally, in developing the cooperative infrastructures that provide a complementary foil to competitive resourcing mechanisms that drive hypothesis-driven science.

Immunohistochemical evidence of Muc1 expression during rat embryonic development

During embryonic development, studies on mouse and human embryos have established that Muc1/MUC1 expression coincides with the onset of epithelial sheet and glandular formation. This study aimed therefore at evaluating the temporal and spatial expression of Muc1 at different stages of rat development. In this report, 80 animals were included: 64 rat foetuses at 13, 14, 15, 16, 17, 18, 19 and 20 days of gestation from pregnant females (WKAH/Hok), 8 embryos each stage. Standard immunohistochemistry was performed using anti-MUC1 cytoplasmic tail polyclonal antibody (CT33). The reaction was considered positive when more than 5% of the cells were stained; reaction patterns were: L = linear, membrane, C = cytoplasmic and M = mixed; nuclear staining was also recorded. Intensity was graded as negative (−), low (+), moderate (++) and strong (+++). Muc1 expression was observed with a low intensity on 13th day (13 D) in the stomach, lung and kidney; at 14 d, small intestine and pancreas were also reactive; at 16 D, liver and esophagus and at 18 D, trachea and salivary glands. During the development, intensity increased while the pattern of expression changed: at the first days of gestation, it was predominantly linear and apical while during further development an increase in cytoplasmic expression was observed. Trachea, stomach, kidney and lung epithelia were the more reactive tissues. In specimens belonging to neonates and adults, all tissues analyzed showed similar Muc1 expression. The findings of this study assess that Muc1 is highly expressed in the epithelial rat embryonic development.

[Investigation of potential risk factors for Salmonella enterica subsp enterica serotype Napoli: a nested case-control study in Lombardia region]

Enter-net surveillance system has detected the re-emergence of Salmonella enterica subsp enterica serotype Napoli (S. Napoli) since 2002. Preliminary data show that food vehicle could not be the only one implicated in the transmission of this serotype. A nested case-control study has been conducted using data form a prospective cohort: for each salmonellosis notification in Lombardia from May 2004 to December 2005 an ad hoc epidemiological investigation has been performed. Cases have been defined as subjects affected by salmonellosis with a positive faecal sample for Salmonella serotype Napoli and controls as subjects affected by salmonellosis with a positive faecal sample for Salmonella serotype not Napoli. Among 2185 salmonellosis notifications collected by 12 of 15 Local Health Authorities, we identified 67 cases and 867 controls. Infection due to S. Napoli were significantly more common among subjects with exposure to surface water (adjusted Odds Ratio (OR) = 3,82; 95% Confidence Interval (C.I.)=1,03-14,19), to domestic animals (adjusted OR = 3,22; 95% C.I. = 1,28-8,10) and among person who practice activities connected to surface water (adjusted OR 3,88; 95% C.I.=1,15-13,05) compared to subjects not exposed to these factors. Hyperendemia of S. Napoli could be attributable to an animal reservoir not yet identified: surface water contamination may be a direct (waterborne infection) or indirect (foodborne infection) vehicle for transmission of S. Napoli. behaviour. Regarding the relations of the neuroendocrine parameters and driving behaviour, positive correlations were observed between dopamine levels and frequency of driving violations while a negative relationship was found between adrenaline levels and frequency of driving errors. In conclusion the identification of psycho-physiological variables related to driving risky behaviour might be a useful instrument to design traffic safety programs tailored to high risk subjects.

Associations of squaric acid and its anions as multiform building blocks of hydrogen-bonded molecular crystals

Squaric acid, H(2)C(4)O(4) (H(2)SQ), is a completely flat diprotic acid that can crystallize as such, as well as in three different anionic forms, i.e. H(2)SQ.HSQ(-), HSQ(-) and SQ(2-). Its interest for crystal engineering studies arises from three notable factors: (i) its ability of donating and accepting hydrogen bonds strictly confined to the molecular plane; (ii) the remarkable strength of the O-H...O bonds it may form with itself which are either of resonance-assisted (RAHB) or negative-charge-assisted [(-)CAHB] types; (iii) the ease with which it may donate a proton to an aromatic base which, in turn, back-links to the anion by strong low-barrier N-H+...O(1/2-) charge-assisted hydrogen bonds. Analysis of all the structures so far known shows that, while H(2)SQ can only crystallize in an extended RAHB-linked planar arrangement and SQ(2-) tends to behave much as a monomeric dianion, the monoanion HSQ(-) displays a number of different supramolecular patterns that are classifiable as beta-chains, alpha-chains, alpha-dimers and alpha-tetramers. Partial protonation of these motifs leads to H(2)SQ.HSQ(-) anions whose supramolecular patterns include ribbons of dimerized beta-chains and chains of emiprotonated alpha-dimers. The topological similarities between the three-dimensional crystal chemistry of orthosilicic acid, H(4)SiO(4), and the two-dimensional one of squaric acid, H(2)C(4)O(4), are finally stressed.

General rules for the packing of hydrogen-bonded crystals as derived from the analysis of squaric acid anions: aminoaromatic nitrogen base co-crystals

Preparation and single-crystal X-ray structure determination of three co-crystals of hydrogen squarate, HSQ(-), with 2-aminopyrimidine, 3-aminopyridine and 4-aminopyridine, and one of squarate, SQ(2-), with 8-aminoquinoline are reported. Their crystal packings are analyzed and discussed in terms of the intermolecular O--H...O, N--H...O/N and C--H...O hydrogen bonds formed. Although the fine details of the supramolecular architecture are barely rationalizable, the comparative analysis of the data makes it possible to suggest some simple rules that may be of general application for the packing of hydrogen-bonded crystals, i.e. Rule 1: 'All hydrogen-bond acceptors available in a molecule will be engaged in hydrogen bonding as far as there are available donors'; Rule 2: 'The hydrogen-bond acceptors will be saturated in order of decreasing strength of the hydrogen bonds formed'.

Intermolecular N-H...O Hydrogen Bonding Assisted by Resonance. II. Self Assembly of Hydrogen-Bonded Secondary Enaminones in Supramolecular Catemers

The crystal structures of 15 compounds containing the 2-en-3-amino-1-one heterodienic system and forming intermolecular N—H...O hydrogen bonds assisted by resonance (RAHB) are reported: (1) 3-phenylamino-2-cyclohexen-1-one; (2) 3-(4-methoxyphenylamino)-2-cyclohexen-1-one; (3) 3-(4-chlorophenylamino)-2-cyclohexen-1-one; (4) 3-(4-methoxyphenylamino)-2-methyl-2-cyclohexen-1-one; (5) 3-(4-methoxyphenylamino)-5-methyl-2-cyclohexen-1-one; (6) 3-isopropylamino-5,5-dimethyl-2-cyclohexen-1-one; (7) 3-phenylamino-5,5-dimethyl-2-cyclohexen-1-one; (8) 3-(3-methoxyphenylamino)-5,5-dimethyl-2-cyclohexen-1-one; (9) N,N-3-aza-pentane-1,5-bis[1-(3-oxo-5,5-dimethyl-1-cyclohexenyl)]; (10) 3-phenylamino-6,6-dimethyl-2-cyclohexen-1-one; (11) 3-(2-methoxyphenylamino)-6,6-dimethyl-2-cyclohexen-1-one; (12) 3-(3-chlorophenylamino)-6,6-dimethyl-2-cyclohexen-1-one; (13) 3-(4-chlorophenylamino)-6,6-dimethyl-2-cyclohexen-1-one; (14) 1-(4-chlorophenyl)-4-(4-chlorophenylamino)-6-methyl-2-pyridone; (15) 3-(4-chlorophenylamino)-5-phenyl-2-cyclopenten-1,4-dione. All compounds form intermolecular N—H...O=C hydrogen bonds assisted by resonance connecting the heteroconjugated enaminonic groups in infinite chains. Chain morphologies are analyzed to find out crystal engineering rules able to predict and interpret the crystal packing. Simple secondary enaminones [i.e. (1)–(13) together with a number of structures retrieved from the Cambridge Structural Database] are found to form hydrogen bonds having π-delocalizations, as characterized by a C=O bond-length average of 1.239 ± 0.004 Å, and hydrogen-bond strengths, represented by the N...O average distance of 2.86 ± 0.05 Å, very similar to those previously found for amides. Enaminones, however, can be easily substituted by chemical groups able to influence both π-conjugations and N...O hydrogen-bond distances. Some substituted enaminones, retrieved from the literature, display, in fact, N...O hydrogen-bond distances as short as 2.627 Å and large π-delocalizations with C=O double-bond distances as long as 1.285 Å. These effects appear to be associated with (a) the presence of further π-conjugated systems involving the C=O and NH groups of the enaminone moiety or (b) the transformation of the enaminone carbonyl group in an amidic function.

Conserved segment identification

The quantitative study of evolution based on comparative map data is dependent on the definition and identification of conserved segments remaining after interchromosomal exchanges such as reciprocal translocation. Because of experimental error and, more important, extensive local intrachromosomal rearrangement, it is difficult to reconstruct the configuration of conserved segments produced by interchromosomal exchanges. We present a formula to evaluate possible conserved segments and an algorithm which seeks the partition of the genome into segments optimal under this evaluation. Application is made to the human-mouse comparison.

Stereochemistry of serotonin receptor ligands from crystallographic data. Crystal structures of NAN-190.HBr, 1-phenylbiguanide, MDL 72222 and mianserin.HCl and selectivity criteria towards 5-HT1, 5-HT2, and 5-HT3 receptor subtypes

The crystal and molecular structures of the following serotoninergic drugs have been determined: (1) 1-(2-methoxyphenyl)-4-[4-(2-phthalimido)butyl]piperazine hydrobromide hemihydrate (NAN-190.HBr), C23H28N3O3+.Br-.1/2H2O, M(r) = 483.42, monoclinic, C2/c, a = 21.916 (4), b = 15.207 (2), c = 14.052 (2) A, beta = 101.56 (1) degree, V = 4588 (1) A3, Z = 8, Dx = 1.40 Mgm-3, lambda (Mo K alpha) = 0.71069 A, mu = 1.823 mm-1, F(000) = 2008, T = 295 K, R = 0.035 for 2617 observed reflections; (2) N-phenylimidocarbonimidic diamide (1-phenylbiguanide), C8H11N5, M(r) = 177.21, monoclinic, P2(1)/c, a = 9.781 (2), b = 35.040(5), c = 11.000 (2) A, beta = 97.72(1) degree, V = 3736(1)A3, Z = 16, Dx = 1.26 Mg m-3, lambda (Mo K alpha) = 0.71069 A, mu = 0.084 mm-1, F(000) = 1504, T = 295 K, R = 0.070 for 3407 observed reflections; (3) 8-methyl-8-azabicyclo[3.2.1]oct-3yl 3,5-dicholorobenzoate (MDL 72222), C15H17Cl2NO2, M(r) = 314.21, triclinic, P1, alpha = 8.480 (3), b = 9.840 (3), c = 10.158 (4) A, alpha = 90.04 (3), beta = 111.77 (3), gamma = 105.07(3) degrees, V = 755.6(5) A3, Z = 2, Dx = 1.38 Mg m-3, lambda(Mo K alpha) = 0.71069 A, mu = 0.430 mm-1, F(000) = 328, T = 295 K, R = 0.070 for 1685 observed reflections; (4) 1, 2, 3, 4, 10, 14b-hexahydro-2-methyldibenzo[c.f]pyrizino[1, 2-alpha]azepine hydrochloride (mianserin. HCl), C18H21N2+. Cl-, M(r) = 300.83, monoclinic, P2(1)/a, a = 9.014 (2), b = 14.917 (2), c = 12.412 (2) A, beta = 108.84 (1) degree, V = 1579.5 (5) A3, Z = 4, Dx = 1.26 Mg m-3, lambda(Mo K alpha) = 0.71069 A, mu = 0.237 mm-1, F(000) = 640, T = 295 K, R = 0.063 for 1493 observed reflections. A systematic structural analysis of the present compounds and others known to interact with the 5-HT1, 5-HT2 and 5-HT3 receptors allows to identify their similarities with the endogenous ligand serotonin (5-HT) and the stereochemical differences which determine selectivity for the various receptor subtypes. The pharmacophoric feature for 5-HT receptor binding is identified in a constant-length vector linking an aromatic ring with a protonated nitrogen, while specific affinities for receptorial subtypes and the nature of the effect appear to be modulated by the dimensions of the substituents at nitrogen.

A remarkable nonlinear invariant for evolution with heterogeneous rates

A model for DNA or protein sequence evolution is proposed where each position belongs to one of two distinct classes. The two classes evolve at different rates. For a phylogeny on four species, we find a cubic function of 4-tuple occurrence frequencies that is nontrivially invariant no matter what the proportion of positions in each rate class. This result refutes the major criticism of nonlinear polynomial invariants.

Karyotype distributions in a stochastic model of reciprocal translocation

A random process of reciprocal translocation for a fixed number k of chromosomes (or arms) will have an equilibrium distribution of chromosome lengths. In this paper we calculate this distribution, by analytical means for k = 2 and partially for k = 3, and simulate the means of the marginal distributions for higher k. We compare this with a random (i.e., ahistorical) distribution of genomic DNA among k chromosomes and to a selection of karyotypes of real organisms. The results motivate a revised model where translocations giving rise to undersize chromosomes are disadvantaged.

Phylogenetic invariants for more general evolutionary models

An invariant Q of a tree T under a k-state Markov model, where a generalized time parameter is identified with the E edges of T, allows us to recognize whether data on N observed species (usually, N DNA sequences, one from each species) can be associated with the N leaves of T in the sense of having been generated on T rather than on any other N-leaf tree. The form of the generalized time parameter is a positive determinant matrix in some semigroup S of Markov matrices. The invariance is with respect to the choice of the set of E matrices in S, one associated with each of the E edges of T. The parametric form of S represents a model of the evolutionary process. In this paper, we apply a general method of finding invariants of a parametrized functional form to find low-degree polynomial invariants for different models. Quadratic invariants are obtained for the Kimura two-parameter model, for a model allowing evolutionary dependence between positions in the sequences and for an asymmetric model that allows for A + T versus G + C asymmetries in DNA base composition. Those invariants are found for trees (unrooted in case of the Kimura model and rooted for the others) with N = 3 or N = 4 terminal vertices. We also find cubic invariants for a ten-parameter model with k = 4 states, for rooted trees with N = 4. In each case, we use implicit function theory to predict the number of algebraically independent invariants and then use this prediction to guide a systematic search for algebraic dependence within the set of invariants produced by our method.

Skewed base compositions, asymmetric transition matrices, and phylogenetic invariants

Evolutionary inference methods that assume equal DNA base compositions and symmetric nucleotide substitution matrices, where these assumptions do not hold, are likely to group species on the basis of similar base compositions rather than true phylogenetic relationships. We propose an invariants-based method for dealing with this problem. An invariant QT of a tree T under a k-state Markov model, where a generalized time parameter is identified with the E edges of T, allows us to recognize whether data on N observed species can be associated with the N terminal vertices of T in the sense of having been generated on T rather than on any other tree with N terminals. The form of the generalized time parameter is a positive determinant matrix in some semigroup S of stochastic matrices. The invariance is with respect to the choice of the set of E matrices in S, one associated with each of the E edges of T. We apply a general "empirical" method of finding invariants of a parametrized functional form. It involves calculating the probability f of all KN data possibilities for each of m sets of E matrices in S to associate with the edges of T, then solving for the parameters using the m equations of form Q(f) = 0. We discuss the problems of finding asymmetric models satisfying the property of semigroup closure, of finding asymmetric models that admit invariants at all, and of the computational complexity of the method. We propose a class of semigroups Sc containing matrices of form [formula: see text] to account for A+T versus G+C asymmetries in DNA base composition. Quadratic invariants are obtained for rooted trees with three and with four terminals. In the latter case the smallest set of algebraically independent invariants is sought. These invariants are applied to data pertaining the fungal evolution and to the origin of mitochondria as bacterial endosymbionts.