The Arabidopsis HEI10 Is a New ZMM Protein Related to Zip3

In numerous species, the formation of meiotic crossovers is largely under the control of a group of proteins known as ZMM. Here, we identified a new ZMM protein, HEI10, a RING finger-containing protein that is well conserved among species. We show that HEI10 is structurally and functionally related to the yeast Zip3 ZMM and that it is absolutely required for class I crossover (CO) formation in Arabidopsis thaliana. Furthermore, we show that it is present as numerous foci on the chromosome axes and the synaptonemal complex central element until pachytene. Then, from pachytene to diakinesis, HEI10 is retained at a limited number of sites that correspond to class I COs, where it co-localises with MLH1. Assuming that HEI10 early staining represents an early selection of recombination intermediates to be channelled into the ZMM pathway, HEI10 would therefore draw a continuity between early chosen recombination intermediates and final class I COs

Effect of dairy matrices on the survival of Streptococcus thermophilus, Brevibacterium aurantiacum and Hafnia alvei during digestion

This study evaluated the ability of dairy matrices, different in composition (with and without fat) and structure (liquid and gel), to enhance microorganisms survival through digestion. The viability of three dairy microorganisms Streptococcus thermophilus, Brevibacterium aurantiacum and Hafnia alvei was measured during in vitro and in vivo digestion. S. thermophilus was highly sensitive to gastric stress, and was not found in the duodenal compartment. B. auranticum was moderately sensitive to gastric stress but resistant to duodenal stress. H. alvei was highly resistant to both stresses. LIVE/DEAD confocal microscopy´s images, probed the effect of low pH on microorganisms survival. However, in vivo analyses (16S rRNA gene metabarcoding) failed to confirm in vitro observations since tested microorganisms were not detected. Despite of the different evolutions during digestion on buffer capacity, lipolysis, and rheological characteristics, we did not observe any protective effect of the dairy matrices on microorganisms survival

Chiasma shortage in <i>hei10</i> mutants.

<p>SD: Standard Deviation.</p

Characterisation of mutations in the HEI10 genomic region.

<p>Arrows indicate the orientation of the open reading frame, arrowheads indicate primer locations, and exons are shown as boxes (red: UTR, black: CDS). The mutations linked to a meiotic defect are shown in green, while insertions that do not induce a detectable phenotype are indicated in black. For T-DNA inserts, the FST name is given, together with the orientation of the sequenced flanking border. Lb: T-DNA left border.</p

<i>hei10</i> mutants show a reduction in chiasma formation.

<p>DAPI Staining of wild-type (Wt, Ws-4, A-H) and <i>hei10-1</i> (I, P) PMCs during meiosis. A, I: leptotene; B, J: Pachytene; C, K: Diplotene; D, L: Diakinesis; E, M: Metaphase I; F, N: Metaphase II; G,O: Anaphase II; H, P: Telophase II. Heterochromatin (rDNA and centromeres) is stained more brightly than euchromatic arm regions. Bar: 10 µm.</p

HEI10 and MLH1 co-localise from late pachytene to diakinesis.

<p>Co-immunolocalisation of HEI10 (red) and MLH1 (green) on wild-type (Col-0) PMC chromosomes after acetic acid spreading. Bar: 10 µm. For each cell, individual signals are shown as well as the overlay of both signals (HEI10 and MLH1) and merged signals of both antibodies together with DAPI. A:Zygotene, B–C: early Pachytene, D: Late pachytene, E: Diplotene, F–G: Diakinesis. With DAPI, heterochromatin (centromeres and repeated rDNA regions) is stained more brightly than euchromatin. Bar: 10 µm.</p

Class I crossovers are absent in <i>hei10</i> mutants.

<p>Immunolocalisation of MLH1 in wild type (Wt, A–B) and <i>hei10-2</i> (C–D) mutant PMCs at diakinesis. For each genotype the MLH1 signal alone (A, C) or a merge signal with DAPI staining is shown. With DAPI, centromeres are stained more intensively than the chromosome arms. The arrow indicates a residual chiasma in <i>hei10-2</i>. Bar: 10 mm.</p

HEI10 is a ZMM protein.

<p>SD: Standard Deviation.</p>1<p>ratio between map distance with and without adj CO.</p

Early recombination defects are not detected in <i>hei10</i> mutants.

<p>DAPI staining of Metaphase I (A, C) and Anaphase I (B, D) PMCs in <i>rad51</i> (A, B) or <i>rad51hei10</i> (hei10-2 allele, C, D) mutants. Bar: 10 µm. Co-immunolocalisation of ASY1 (red) and AtDMC1 (green) in wild-type (wt, E) and mutant meiocytes (<i>hei10-2</i>, F). Bar: 5 µm.</p

Recombination rates in the <i>hei10</i> mutant.

1<p>calculated using the Perkin equation (Perkins 1949 Genetics 34:607).</p><p>PD: Parental Ditype, TT: TetraType, NPD: Non Parental Ditype.</p