An intriguing outcome of hybridisation is the emergence of clonally and hemiclonally reproducing hybrids, that can sustain, reproduce, and lead to the emergence of polyploid forms. However, the ...maintenance of diploid and polyploid hybrid complexes in natural populations remains unresolved. We selected water frogs from the Pelophylax esculentus complex to study how diploid and triploid hybrids, which reproduce hemiclonally via hybridogenesis, are maintained in natural populations. During gametogenesis in diploid hybrids, one of the parental genomes is eliminated, and the remaining genome is endoreplicated. In triploid hybrids, the single-copy genome is typically eliminated, while genome endoreplication does not occur. To investigate how diploid and triploid hybrid frogs reproduce in populations without parental species, we crossed these hybrid animals from two separate pure hybrid populations located in Poland. Using cytogenetic analysis of tadpoles that emerged from the crosses, we established which gametes were produced by parental hybrids. The majority of hybrid females and hybrid males produced one type of gamete with the P. ridibundus genome. However, in both studied populations, approximately half of the diploid and triploid hybrids simultaneously produced gametes with different genome compositions and ploidy levels, specifically, the P. ridibundus and P. lessonae genomes, as well as diploid gametes with genomes of both parental species. Triploid hybrid males and females mostly produced haploid gametes with the P. lessonae genome; however, gametes with the P. ridibundus genome have also been observed. These results suggest that not all hybrids follow the classical hybridogenetic reproduction program and reveal a significant level of alterations in the gametogenesis pathways. In addition, we found a variable survival rate of particular progeny genotypes when we crossed hybrid females with different males suggesting the important role of postzygotic barriers on the maintenance of pure hybrid systems. We suggest that the observed variability in produced gametes and the different survival rate of the progeny with certain genotypes is crucial for the existence of pure hybrid systems.
DNA elimination is a radical form of gene silencing and occurs both in somatic and germ cells. The programmed DNA elimination occurs during gametogenesis in interspecies hybrids that reproduce by ...hybridogenesis (stick insects, fishes, and amphibians) and concerns removal of whole genomes of one of the parental species and production of clonal gametes propagating the genome of the other species. The cellular mechanisms differ considerably in hybridogenetic insects and fishes but remains unknown in edible frogs Pelophylax esculentus, natural hybrids between Pelophylax lessonae and Pelophylax ridibundus. Here we report DNA elimination mechanism in early developing gonads of diploid and triploid hybrid frogs, studied by TEM, immunofluorescence, and cytochemistry. In gonocytes of both sexes (primary oogonia and prespermatogonia), micronuclei emerge as detached nuclear buds formed during interphase. We found depletion of nuclear pore complexes in micronuclear membrane and chromatin inactivation via heterochromatinization followed by degradation of micronuclei by autophagy. Micronuclei formation does not lead to apoptotic cell death showing that genome elimination is a physiological process. Chromatin elimination via micronuclei in P. esculentus is unique among hybridogenetic animals and contributes to broadening the knowledge about reproductive modes in animals.
Hybridogenesis is a hemiclonal reproductive strategy in diploid and triploid hybrids. Our study model is a frog
P. esculentus
(diploid RL and triploids RLL and RRL), a natural hybrid between
P. ...lessonae
(LL) and
P. ridibundus
(RR). Hybridogenesis relies on elimination of one genome (L or R) from gonocytes (G) in tadpole gonads during prespermatogenesis, but not from spermatogonial stem cells (SSCs) in adults. Here we provide the first comprehensive study of testis morphology combined with chromosome composition in the full spectrum of spermatogenic cells. Using genomic
in situ
hybridization (GISH) and FISH we determined genomes in metaphase plates and interphase nuclei in Gs and SSCs. We traced genomic composition of SSCs, spermatocytes and spermatozoa in individual adult males that were crossed with females of the parental species and gave progeny. Degenerating gonocytes (24%–39%) and SSCs (18%–20%) led to partial sterility of juvenile and adult gonads. We conclude that elimination and endoreplication not properly completed during prespermatogenesis may be halted when gonocytes become dormant in juveniles. After resumption of mitotic divisions by SSCs in adults, these 20% of cells with successful genome elimination and endoreplication continue spermatogenesis, while in about 80% spermatogenesis is deficient. Majority of abnormal cells are eliminated by cell death, however some of them give rise to aneuploid spermatocytes and spermatozoa which shows that hybridogenesis is a wasteful process.
Baler-wrappers are machines designed to produce high-quality forage, in accordance with the requirements of sustainable agriculture. Their complicated structure, and significant loads occurring ...during operation, prompted the creation of systems for controlling the machines' processes and measuring the most important work parameters, in this work. The compaction control system is based on a signal from the force sensors. It allows for detection differences in the compression of the bale and additionally protects against overload. The method of measuring the swath size, with the use of a 3D camera, was presented. Scanning the surface and travelled distance allows for estimating the volume of the collected material-making it possible to create yield maps (precision farming). It is also used to vary the dosage of ensilage agents, that control the fodder formation process, in relation to the moisture and temperature of the material. The paper also deals with the issue of measuring the weight of the bales-securing the machine against overload and collecting data for planning the bales' transport. The machine, equipped with the above-mentioned systems, allows for safer and more efficient work, and provides information about the state of the crop in relation to a geographical position, which allows for further inferences.
Agrotechnological procedures related to forest management, including planting, are burdensome and the energy expenditure of the people working is very high. Nowadays, planting is usually carried out ...manually, and sometimes with the use of planters coupled to universal tractors. Occasionally, planters mounted on high-power carriers are used, and usually the seedlings are removed from their cassettes and placed manually into the planter’s storage unit. In connection with the above, the prototype of a mobile automatic device for performing forest regeneration tasks and afforestation of post-agricultural and reclaimed areas (RoboFoR) was designed. The main task of this vehicle is planting forest tree seedlings with a covered root system, which are collected directly from their nursery cassettes. This study presents the structure, principle of operation and results of operational tests of the seedling storage and feeding unit. It was found that the unit achieved the expected work efficiency. However, imperfections in the system related to the non-centralized distribution of seedlings in containers and the high variability of biometric characteristics of the seedlings were also identified. A new solution for this unit was proposed, which will increase the reliability of collecting the seedlings. A new solution requires greater computational power of the control unit as well as equipping the sensor system with a technologically advanced root neck detection system. The new concept also assumes the possibility of independent movement of each gripper.
The aim of the study conducted upon completion of obligatory palliative medicine courses among 588 medical students at two universities was to compare their attitudes toward euthanasia. Four hundred ...ninety-two (84.97 %) students were Catholics; 69 (11.73 %) declared they would practice euthanasia, 303 (51.53 %) would not, and 216 students (36.73 %) were not sure. The idea of euthanasia legalisation was supported by 174 (29.59 %) respondents, opposed by 277 (47.11 %), and 137 (23.30 %) were undecided. Five hundred fifty-six (94.56 %) students did not change their attitudes toward euthanasia after palliative medicine courses. Students from the two universities were found to have different opinions on practicing euthanasia, euthanasia law and possible abuse which might follow euthanasia legalisation, but they shared similar views on the choice of euthanasia if they themselves were incurably ill and the legalisation of euthanasia. Gender and religion influenced students’ answers. Differences observed between medical students at the two universities might be related to gender and cultural differences.
Gold(I) complexes with phosphine ligands—Au(TrippyPhos)Cl (1) (TrippyPhos = 1-2-bis(tert-butyl)phosphinophenyl-3,5-diphenyl-1H-pyrazole), Au(BippyPhos)Cl0.5CH2Cl2 (2) (BippyPhos = ...5-(di-tert-butylphosphino)-1′, 3′, 5′-triphenyl-1′H-1,4′bipyrazole), and Au(meCgPPh)Cl (3) (meCgPPh = 1,3,5,7-tetramethyl-6-phenyl-2,4,8-trioxa-6-phosphaadamantane—were investigated as types of bioactive gold metallodrugs. Complexes (1)–(3) were characterized using IR, 1H, 13C, 31P NMR spectroscopy, elemental analysis and mass spectrometry (FAB-MS). Complexes of (1) and (2) exhibited substantial in vitro cytotoxicity (IC50 = 0.5–7.0 μM) against both the cisplatin-sensitive and -resistant variants of the A2780 human ovarian carcinoma cell line, as well as against the A549 human lung carcinoma, K562 chronic myelogenous leukemia, and HeLa (human cervix carcinoma) cells. However, among the compounds studied, complex (2) showed the most promising biological properties: the highest stability in biologically relevant media, selectivity towards cancer cells over the non-cancer cells (HUVEC, human umbilical vein endothelial cells), and the highest inhibitory effect on cytosolic NADPH-dependent reductases in A2780 and A2780cis cells among the gold complexes under analysis.
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