Attempts to Diminish the Drawbacks of Polylactic Acid Designed for 3D/4D Printing Technology-Fused Deposition Modeling

In order to improve thermal behavior and dimensional strability of polylactic acid (PLA) designed both for 3D and 4D printing technology-fused deposition modeling (FDM) using a scalable procedure, the polymer was melt compounded with additives which control the morphology by crystallization and/or reinforcing. Using the formulations which provide polylactic acid (PLA) improved thermo-mechanical properties and desired dimensional stability, the new materials were shaped, on a laboratory line, as filaments for printing technology. The selected compounds were than scaled up on a 50 kg/h compounding line into granules which prove to have good shapability as filaments for printing technology (1.85 +/- 0.05 mm diameter, required ovality, good appearance and smooth surface) and performed properly at 3D printing. The obtained results proved that functional properties of PLA can be improved by various methods so that, depending on the reached performances, the new material can be converted through printing technology into items for performance applications. The novelty of the article is related to the fact that it identifies a modifying solution for controlling the morphology of a type of PLA designed for 3D printing that already has an advanced crystallinity.

Rapid comeback of males: evolution of male-killer suppression in a green lacewing population

Evolutionary theory predicts that the spread of cytoplasmic sex ratio distorters leads to the evolution of host nuclear suppressors, although there are extremely few empirical observations of this phenomenon. Here, we demonstrate that a nuclear suppressor of a cytoplasmic male killer has spread rapidly in a population of the green lacewing Mallada desjardinsi . An M. desjardinsi population, which was strongly female-biased in 2011 because of a high prevalence of the male-killing Spiroplasma endosymbiont, had a sex ratio near parity in 2016, despite a consistent Spiroplasma prevalence. Most of the offspring derived from individuals collected in 2016 had 1 : 1 sex ratios in subsequent generations. Contrastingly, all-female or female-biased broods appeared frequently from crossings of these female offspring with males derived from a laboratory line founded by individuals collected in 2011. These results suggest near-fixation of a nuclear suppressor against male killing in 2016 and reject the notion that a non-male-killing Spiroplasma variant has spread in the population. Consistently, no significant difference was detected in mitochondrial haplotype variation between 2011 and 2016. These findings, and earlier findings in the butterfly Hypolimnas bolina in Samoa, suggest that these quick events of male recovery occur more commonly than is generally appreciated.

Novel series os pea symbiotic mutants induced in the SGE line

Using ethylmethansulphonate the chemical mutagenesis of the pea laboratory line SGE was performed. During analysis of 425 families (2069 plants) of М₂ progeny 45 putative mutants were selected, among them 30 mutants forming ineffective nodules (Fix^– phenotype), 13 mutantsunable to form nodules (Nod^– phenotype), and 2 mutants forming a few nodules (Nod^+/– phenotype). For 1 Nod^– and 5 Fix^– mutants monogenic inheritance and recessive phenotype manifestation were demonstrated. For Fix^–mutant SGEFix^––9 an additional mutation leading to Nod^+/– phenotype was shown. Complementation analysis showed that the mutant phenotype of the SGEFix<span style="font-size:11px">^- - </span>5 line is caused by a mutation in the sym33 gene, of theSGEFix^––6 linein the sym40 gene, of the SGEFix^––7 line in the sym27 gene, and of the SGEFix^––8 linein the sym25 gene.

Warsaw Wild Captive Pisula Stryjek rats (WWCPS) - Establishing a breeding colony of Norway Rat in captivity

Warsaw Wild Captive Pisula Stryjek rats (WWCPS) - Establishing a breeding colony of Norway Rat in captivity It is believed that the history of laboratory rat dates back to 1820-ies, which is about 300 generations. This relatively short evolutionary distance, drastically different environment and selective breeding could have caused differences in behaviour between the laboratory rat and his wild counterpart - Norway rat (Rattus norvegicus). The vast majority of research concerning differences between wild and laboratory rats was conducted over 30 years ago. The knowledge acquired as a result of that research seems far from being complete. Over a quarter of a century could have deepened the described differences. Nowadays the change in experimental approach, in favour of low stress conditions, can give a new insight into this problem. This article describes process of establishing a laboratory line of wild Norway rat, which will take part in a broad series of comparative studies. 16 wild rats were trapped in 5 distant parts of Warsaw. Most of wild rats successfully adapted to captive conditions, mating successfully and producing litters, which have survived to adolescence.

The Genetic Structure of the Raleigh Natural Population of Drosophila melanogaster Revisited

The Raleigh natural population of Drosophila melanogaster was reanalyzed with special attention to possible dysgenic effects during the extraction of chromosomes. About 600 second chromosomes were extracted from the Raleigh natural population, half in the cytoplasm of wild-caught females (native genetic background) and half in the cytoplasm of the laboratory line, C160(In(2LR)SM1, Cy/In(2LR)bwV1) (foreign genetic background). We could not find significant differences between the two extraction schemes in the frequency of lethal second chromosomes (Q = 0.252 for the lines with the negative genetic background vs. 0.231 for the lines with the foreign genetic background) or in the homozygous detrimental (D) and lethal (L) loads (D = 0.210 vs. 0.251; L = 0.287 vs. 0.264). The effective size of the population was estimated to be ~19,000, based on the allelism rate of lethal-bearing chromosomes. The homozygous load markedly decreased in the 15 years since a previous study of the same population.