Molecular characterization of a genomic interval with highly uneven recombination distribution on maize chromosome 10 L
Authors: Rentao Song
Zhengkai Xu
Fei Wang
Gang Wang
Liangliang Zhou
Yuanping Tang
Jianping Xu
Journal: Genetica (2011)
Discipline: MOLECULAR BIOLOGY & GENETICS
Keywords: Homologous recombination; Meiosis; Genetic variability; Chromosome 10; Recombinant events
Affiliations: Shanghai Key Laboratory of Bio-Energy Crop, School of Life Sciences, Shanghai University, 99 Shangda Road, Shanghai 200444, People's Republic of China.

Abstract:  Homologous recombination in meiosis provides the evolutionary driving force in eukaryotic organisms by generating genetic variability. Meiotic recombination does not always occur evenly across the chromosome, and therefore genetic and physical distances are not consistently in proportion. We discovered a 278 kb interval on the long arm of chromosome 10 (10 L) through analyzed 13,933 descendants of backcross population. The recombinant events distributed unevenly in the interval. The ratio of genetic to physical distance in the interval fluctuated about 47-fold. With the assistance of molecular markers, the interval was divided into several subintervals for further characterization. In agreement with previous observations, high gene-density regions such as subinterval A and B were also genetic recombination hot subintervals, and repetitive sequence-riched region such as subinterval C was also found to be recombination inert at the detection level of the study. However, we found an unusual subinterval D, in which the 72-kb region contained 6 genes. The gene-density of subinterval D was 5.8 times that of the genome-wide average. The ratio of genetic to physical distance in subinterval D was 0.58 cM/Mb, only about 3/4 of the genome average. We carried out an analysis of sequence polymorphisms and methylation status in subinterval D, and the potential causes of recombination suppression were discussed. This study was another case of a detailed genetic analysis of an unusual recombination region in the maize genome. 

Retracted: No

PubPeer comments:
 Below are some concerns about several inaccurate issues in the open-access paper with a title of: u201cBisphenols exert detrimental effects on neuronal signaling in mature vertebrate brainsu201d Schirmer, E., Schuster, S., Machnik, P. *Commun. Biol.* 4, 465 (2021). https: doi.org 10.1038 s42003-021-01966-w. 1.tIt is odd to see citations to few references in the Abstract, which must be avoided. 2.t**Abstract** starts with, u201cBisphenols are important plasticizers currently in use and are released at rates of hundreds of tons each year into the biosphere [1u20133].u201d None of the cited references state u201cBisphenolsu201d as u201cimportant plasticizersu201d. This inaccurate and misleading issue has been repeated several times in the entire article. For instance, the Discussion section is concluding with, u201cTogether with similarly sensitive assays they could guide our way to the urgently needed next-generation plasticizers.u201d Actually, bisphenol A (BPA) and bisphenol S (BPS) are not plasticizer additives to plasticize polymers. They are used as monomer for production of polycarbonate (PC) and polyethersulfone (PES) and as monomer and curing agents in some kinds of epoxy resin objects and coating products. It seems that the author confused BPA and BPS with phthalate-based plasticizers, such as dibutyl phthalate (DBP), diethyl phthalate (DEP), diisodecyl phthalate (DIDP), and diisononyl phthalate (DINP). These chemical compounds are organic liquids at room temperature with elevated boiling point widely used to mainly soften polyvinyl chloride (PVC) products, making them ductile and flexible. These plasticizers are physically added to PVC during compounding step along with other additives (fillers, lubricants, pigments, etc.), thus, they can migrate out of PVC product along service life to the surface. That is the reason why plasticized PVC products become brittle after some time in service. These chemical compounds used as plasticizer additives in PVC have their own safety and health concerns. Unlike DBP and other plasticizers of PVC, BPA and BPS are not physically present in the PC and PES products as additives, so, they cannot migrate out via diffusion mechanism. **How BPA and BPS, solid organic chemical compounds with melting points of 158 and 245u2013250 u00b0C, respectively, can soften polymers at room temperature with very limited compatibility with the polymers?** BPA and BPS form strong backbone of macromolecular chains of PC and PES as monomers through polycondensation polymerization reactions that can only be separated from the plastic product (i.e., PC, epoxy) in long term in small quantities through degradation (depolymerization) in very specific conditions. This inaccuracy could lead to misleading and incorrect conclusions. Caption of **Fig. 1a** presents another inaccurate and misleading information, u201cBisphenols are additives in plastic products. As plastic degrades these substances are released into the environment and are then able to pass the bloodu2013brain barrier (BBB). Bisphenol A (BPA), the most widely used plasticizer, is released at millions of tons per year and has devastating effects, for instance during ontogeny. Its substitute bisphenol S (BPS) also appears problematic, but for both bisphenols any effect on the mature brain is unknown.u201d Bisphenols are not additives in plastic products, as explained above, and BPA is not u201cthe most widely used plasticizeru201d. The major consumer of BPA as a chemical raw material (monomer) and also a potential source of its release as a degradation product is PC with global production of approximately 6.15 million metric tons in 2020 (from: Chemical Economics Handbook, 2020). How potential release of traces of BPA from natural degradation of PC in decades can amount to u201cmillions of tons per yearu201d? Polycarbonate waste is non-toxic, harmless and difficult to naturally degrade because of its high environmental stability and strong backbone. It is a thermoplastic material that is recycled after use. 3.tIn the **Introduction** section, u201cFor example, 8 million tons of the plasticizer bisphenol A (BPA; 2,2-bis-(4-hydroxyphenyl)-propane; CAS Registry No. 80-05-7) are produced worldwide each year and 100 tons per year are released into the biosphere [2,3,13,14], making BPA ubiquitously present in the environment from surface water to breast milk [1].u201d This sentence is also inaccurate of naming BPA as a plasticizer additive and the total amount released to environment as a product of plastic degradation. 4.tMoreover, the graphic in **Fig. 1a** is inaccurate and misleading. It clearly indicates that BPA and BPS directly enter our body through drinking from beverages bottles. It should be noted that the largest market for PC is primarily optical media (e.g., compact disks), then in automobile industries, transparent sheets (glass, lenses), medical, and mobile phones. The application of PC for products in contact with food is a minor part of total PC consumption. In addition, PC does not play a major role in the plastic bottles market compared with PEs, PET, PVC, and some other plastic materials. The majority of used beverage bottles that are found in nature are made from polyesters (PET), not PC. 5.t**Introduction** section begins with, u201cPlasticizers are essential ingredients to plastic productionu201d statement, with citation to two references [7,8] (*Chemosphere* 182, 781, (2017); *J. Hazard. Mater.* 344, 179, (2018)). In [7], BPA was stated as an additive (unknown type) and in [8], it was classified as a stabilizer, which are both incorrect. It indicates that some references used in this article are not accurate sources of information. 6.tNext sentence in the **Introduction** states that, u201cHowever, upon degradation of plastic products these additives are released into the environment in large quantity, making plasticizer contamination a serious environmental issue and potential risk for our health [1,9u201312].u201d Additives that have been added to polymers for specific functions are in physical blend with the polymer. Additives can be released from plastic product during the processing step and later gradually in service in long periods of time. They do not need to wait on for degradation of polymer present in the plastic product. As mentioned earlier, PC is a highly stable polymer against degradation, therefore we cannot expect to detect significant amounts of natural degradation products, such as BPA, in short periods of time. The products made from PC (bottles, containers, etc.) are not disposable products, they are usually used for an extended time in stable conditions. , 
 There are comments about Reference [8] of this paper as *J. Hazard. Mater.* 344 (2018) 179 in the following page: https: pubpeer.com publications AB42CE9361811F2F5994AD7DC61B79#3 ,