Do Two Symmetry Breaking Transitions in Photosynthetic Light Harvesting Complexes Form One, Two or More Kibble Zurek Model Topological Defects?

Kibble and Zurek proposed that rapid symmetry breaking transitions in the hot, early universe could result in causally disconnected topological defects such as cosmic strings. This type of first order transition has analogues in certain second order transitions present in condensed matter such as liquid crystals, super fluids, and charge density waves in terms of flux tubes or vortices. Recently, we discovered that Rhodopseudomonas acidophilus photosynthetic light harvesting complex might have different types of coherent ground and excited states, suggesting that there are two different symmetry breaking transitions. The B 850 ground states comprise eight identical rings each containing 18 bacteriochlorophyll components, and each ring has undergone a Bose Einstein phase transition to a charge density wave that lowers the energy. The excited state coherence results from polariton formation from the non-crossing of bosons, here an extension of exciton theory. The result is short-lived quasi-particles with very low mass that can form an unusual BEC. We suggest the oriented, circular B 850 and enclosed singlet B 875 compounds create a new cavity structure with some attributes of a nano pillar. Since both the ground and excited states should contain solitons, we envisage three fast light pulse experiments could be able to map both the Kibble Zurek Model phase transitions and energy transfers as a function of light intensity and time in this complex at room temperature

Aegilops-Secale amphiploids: chromosome categorisation, pollen viability and identification of fungal disease resistance genes

The aim of this study was to assess the potential breeding value of goatgrass-rye amphiploids, which we are using as a “bridge” in a transfer of Aegilops chromatin (containing, e.g. leaf rust resistance genes) into triticale. We analysed the chromosomal constitution (by genomic in situ hybridisation, GISH), fertility (by pollen viability tests) and the presence of leaf rust and eyespot resistance genes (by molecular and endopeptidase assays) in a collection of 6× and 4× amphiploids originating from crosses between five Aegilops species and Secale cereale. In the five hexaploid amphiploids Aegilops kotschyi × Secale cereale (genome UUSSRR), Ae. variabilis × S. cereale (UUSSRR), Ae. biuncialis × S. cereale (UUMMRR; two lines) and Ae. ovata × S. cereale (UUMMRR), 28 Aegilops chromosomes were recognised, while in the Ae. tauschii × S. cereale amphiploid (4×; DDRR), only 14 such chromosomes were identified. In the materials, the number of rye chromosomes varied from 14 to 16. In one line of Ae. ovata × S. cereale, the U-R translocation was found. Pollen viability varied from 24.4 to 75.4%. The leaf rust resistance genes Lr22, Lr39 and Lr41 were identified in Ae. tauschii and the 4× amphiploid Ae. tauschii × S. cereale. For the first time, the leaf rust resistance gene Lr37 was found in Ae. kotschyi, Ae. ovata, Ae. biuncialis and amphiploids derived from those parental species. No eyespot resistance gene Pch1 was found in the amphiploids

Sex Reversal in Zebrafish fancl Mutants Is Caused by Tp53-Mediated Germ Cell Apoptosis

The molecular genetic mechanisms of sex determination are not known for most vertebrates, including zebrafish. We identified a mutation in the zebrafish fancl gene that causes homozygous mutants to develop as fertile males due to female-to-male sex reversal. Fancl is a member of the Fanconi Anemia/BRCA DNA repair pathway. Experiments showed that zebrafish fancl was expressed in developing germ cells in bipotential gonads at the critical time of sexual fate determination. Caspase-3 immunoassays revealed increased germ cell apoptosis in fancl mutants that compromised oocyte survival. In the absence of oocytes surviving through meiosis, somatic cells of mutant gonads did not maintain expression of the ovary gene cyp19a1a and did not down-regulate expression of the early testis gene amh; consequently, gonads masculinized and became testes. Remarkably, results showed that the introduction of a tp53 (p53) mutation into fancl mutants rescued the sex-reversal phenotype by reducing germ cell apoptosis and, thus, allowed fancl mutants to become fertile females. Our results show that Fancl function is not essential for spermatogonia and oogonia to become sperm or mature oocytes, but instead suggest that Fancl function is involved in the survival of developing oocytes through meiosis. This work reveals that Tp53-mediated germ cell apoptosis induces sex reversal after the mutation of a DNA–repair pathway gene by compromising the survival of oocytes and suggests the existence of an oocyte-derived signal that biases gonad fate towards the female developmental pathway and thereby controls zebrafish sex determination

Pragmatic skills predict online counterfactual comprehension:Evidence from the N400

Counterfactual thought allows people to consider alternative worlds they know to be false. Communicating these thoughts through language poses a social-communicative challenge because listeners typically expect a speaker to produce true utterances, but counterfactuals per definition convey information that is false. Listeners must therefore incorporate overt linguistic cues (subjunctive mood, such as in If I loved you then) in a rapid way to infer the intended counterfactual meaning. The present EEG study focused on the comprehension of such counterfactual antecedents and investigated if pragmatic ability—the ability to apply knowledge of the social-communicative use of language in daily life—predicts the online generation of counterfactual worlds. This yielded two novel findings: (1) Words that are consistent with factual knowledge incur a semantic processing cost, as reflected in larger N400 amplitude, in counterfactual antecedents compared to hypothetical antecedents (If sweets were/are made of sugar). We take this to suggest that counterfactuality is quickly incorporated during language comprehension and reduces online expectations based on factual knowledge. (2) Individual scores on the Autism Quotient Communication subscale modulated this effect, suggesting that individuals who are better at understanding the communicative intentions of other people are more likely to reduce knowledge-based expectations in counterfactuals. These results are the first demonstration of the real-time pragmatic processes involved in creating possible worlds