Meiotic recombination, including crossovers (COs) and gene conversions (GCs), impacts natural variation and is an important evolutionary force. COs increase genetic diversity by redistributing existing variation, whereas GCs can alter allelic frequency. Here, we sequenced Arabidopsis Landsberg erecta (Ler) and two sets of all four meiotic products from a Columbia (Col)/Ler hybrid to investigate...

GC-biased gene conversion (gBGC) is a process associated with recombination that favors the transmission of GC alleles over AT alleles during meiosis. gBGC plays a major role in genome evolution in many eukaryotes. However, the molecular mechanisms of gBGC are still unknown. Different steps of the recombination process could potentially cause gBGC: the formation of double-strand breaks (DSBs), ...

High-resolution low-power Direct Digital Frequency Synthesizers (DDFS) with small chip area are investigated. Lookup tables for sine and cosine yield the leading bits of the amplitudes. A CORDIC interpolation scheme enhances the amplitude precision. Systematic case studies using VHDL – models and synthesis indicate, that optimum LUT/CORDIC ratios can minimize use of power and silicon area. Intr...

In most organisms, meiotic chromosome segregation is dependent on crossovers (COs), which enable pairs of homologous chromosomes to segregate to opposite poles at meiosis I. In mammals, the majority of meiotic chromosome segregation errors result from a lack of COs between homologs. Observations in Homo sapiens and Drosophila melanogaster have revealed a second class of exceptional events in wh...

Meiotic recombination involves the repair of double-strand break (DSB) precursors as crossovers (COs) or noncrossovers (NCOs). The proper number and distribution of COs is critical for successful chromosome segregation and formation of viable gametes. In budding yeast the majority of COs occurs through a pathway dependent on the ZMM proteins (Zip2-Zip3-Zip4-Spo16, Msh4-Msh5, Mer3), which form f...

Spo11 is the topoisomerase-like enzyme responsible for the induction of the meiosis-specific double strand breaks (DSBs), which initiates the recombination events responsible for proper chromosome segregation. Nineteen PCR-induced alleles of SPO11 were identified and characterized genetically and cytologically. Recombination, spore viability and synaptonemal complex (SC) formation were decrease...

During meiotic recombination, double-strand breaks (DSBs) are formed in chromosomal DNA and then repaired as either crossovers (COs) or non-crossovers (NCOs). In most taxa, the number of DSBs vastly exceeds the number of COs. COs are required for generating genetic diversity in the progeny, as well as proper chromosome segregation. Their formation is tightly controlled so that there is at least...

Meiotic recombination is the most important source of genetic variation in higher eukaryotes. It is initiated by formation of double-strand breaks (DSBs) in chromosomal DNA in early meiotic prophase. The DSBs are subsequently repaired, resulting in crossovers (COs) and noncrossovers (NCOs). Recombination events are not distributed evenly along chromosomes but cluster at recombination hotspots. ...

When programmed meiotic DNA double-strand breaks (DSBs) undergo recombinational repair, genetic crossovers (COs) may be formed. A certain level of this is required for the faithful segregation of chromosomes, but the majority of DSBs are processed toward a safer alternative, namely noncrossovers (NCOs), via nonreciprocal DNA exchange. At the crossroads between these two DSB fates is the Msh4-Ms...

This paper reviews spur reduction techniques used in direct digital synthesizers (DDSs) or numerically controlled oscillators (NCOs). First, the classification and operation of conventional DDSs are reviewed. Covered are the pulse output DDS, sine output DDS, fractional divider, and phase interpolation DDS. It is shown that DDSs produce spurs as well as the desired output frequency due to the a...