New Bird Sexing Strategy Developed in the Order Psittaciformes Involves Multiple Markers to Avoid Sex Misidentification: Debunked Myth of the Universal DNA Marker

Sexing of birds is indispensable for scientific, breeding and conservation programs but is difficult in many species and is particularly problematic in the case of nestlings showing no sexual dimorphism. Most useful and efficient methods of sex determination are based on unique features of the Z and W sex chromosomes detected via PCR to distinguish males (ZZ) and females (ZW). During the last twenty-five years researchers searched for the universal marker capable of sexing a maximally wide spectrum of species in a single PCR assay. We screened the phylogenetically representative set of 135 Psittaciformes species including 59 species sexed for the first time. Two known (P2P8, CHD1iA) PCR markers and four additional W/Z polymorphisms (CHD1iE, CHD1i16, CHD1i9 and NIPBLi16) located within the Chromo Helicase DNA binding CHD1 or the Nipped-B homolog NIPBL genes were applied. We present the electrophoretic patterns obtained for the PCR products of the analyzed markers including most typical and atypical patterns allowing sex determination, as well as those obtained when the given marker failed in sexing. Technical aspects of molecular sex determination are discussed: the optimization of amplification conditions, direct PCR and potential misinterpretations. A truly universal marker has not been found, and therefore, we propose a sexing strategy based on multiple CHD1i16, NIPBLi16, CHD1i9 and CHD1iE markers. This new strategy confirms the sex of a given bird with at least two markers detecting independent Z/W polymorphisms, reduces the number of necessary PCR reactions and minimizes the risk of sex misidentification.

Application of RAPD Markers on Sex Determination of Papaya (Carica papaya)

Molecular sex determination of five varieties of Indonesian papaya were investigated using RAPD (Random Amplified Polymorphism DNA) markers. Overall, 12 of 14 primers produced polymorphic bands on either several or all tested varieties. The OPC04 and RAPD2 markers could be used determined sex types on all varieties, whereas others primers are only on certain varieties. The Tangkai Ungu variety can be differentiate by markers: OPA11, OPA14, OPC14, RAPD2, RAPD3, and RAPD5; the Lokal Sumani can be determine using markers: OPA01, OPA11, OPA14, OPC01, OPC04, RAPD2, RAPD3, RAPD5, and RAPD6; the Merah Delima could be determined using OPC04, OPN09, RAPD2, and RAPD5; the Dampit could be determined using OPC01, OPC04, RAPD2, and RAPD6; whereas the Sicincing Panjang could be determined using OPA04, OPA11, OPA14, OPC04, RAPD2, and RAPD3.

Morphological Characterisation And Molecular Sex Determination Of Human Remains From The 15th–17th Centuries In Latvia

Sex determination is one of the most important and initial steps in human profile identification from archaeological material. The aim of the current study was to evaluate the application of molecular approaches alongside morphological methods for sex determination in archaeological human skeletal remains. Human skeletal remains were excavated from three cemeteries: St Gertrude Old Church, Dom Square and St Peter’s Church, of 15th–17th century burials in Rīga, Latvia. Morphological and molecular genetic methods, including amplification of genes AMELX/Y and SRY were used to analyse seven skeletal remains. The conducted analyses of morphological features identified sex in all seven cases (two females and five males). By molecular analyses of mediaeval DNA it was possible to determine sex in five of seven (71%) samples. In all positive cases full agreement between morphological estimation and molecular genetic methods was observed. To conclude, DNA analysis can be considered for sex identification in cases with no signs of sexual dimorphism (juvenile skeletons) or partially preserved skeletons.