Differences in trabecular bone of leptin-deficient ob/ob mice in response to biomechanical loading

Objective: It is known that bone mineral density (BMD) and the strength of bone is predicted by body mass. Fat mass is a significant predictor of bone mineral density which correlates with body weight. This suggests that body fat regulates bone metabolism first by means of hormonal factors and second that the effects of muscle and loading are signaling factors in mechanotransduction. Leptin, a peptide hormone produced predominantly by white fat cells, is one of these hormonal factors. The aim of this study was to investigate and measure by micro-CT the different effects of weight-bearing on trabecular bone formation in mice without the stimulation of leptin.     

Seasonal Changes of Vocal Rates and Their Relation to Territorial Status in Male Galápagos Sea Lions (Zalophus wollebaeki)

Male vocal displays play an important role in sexual selection through both male–male competition and female choice. While this is supported by numerous studies in birds, much less attention has been paid to the role of such displays in mammals. We investigated the function of vocal displays in a polygynous mammal, the Galápagos sea lion (Zalophus wollebaeki). In our study population a large proportion of mature males are unable to establish a territory, providing the opportunity to compare the vocal behaviour between territorial and non‐territorial males. We examined how seasonal patterns of vocalizations differed between territorial and non‐territorial males and how the number of females present in a territory influenced behaviour of territorial males. We found that territorial males vocalized at higher rates than non‐territorial males, and territorial males vocalized more at the onset than towards the end of territory tenure. During the onset of territory‐tenure vocalizations of territorial males were directed more often towards other males than females. Furthermore, we found that vocalizations of territorial males were not only given in male–male interactions, but were also actively directed towards females. Territorial males vocalized at higher rates when more females were present in their territory. Our results suggest that vocalizations are important in male–male interactions, are relevant in territorial disputes and are used as a proxy for females to assess a male’s quality.     

Focus on Weed Control: Herbicides as Weed Control Agents: State of the Art: I. Weed Control Research and Safener Technology: The Path to Modern Agriculture

The purpose of modern industrial herbicides is to control weeds. The species of weeds that plague crops today are a consequence of the historical past, being related to the history of the evolution of crops and farming practices. Chemical weed control began over a century ago with inorganic compounds and transitioned to the age of organic herbicides. Targeted herbicide research has created a steady stream of successful products. However, safeners have proven to be more difficult to find. Once found, the mode of action of the safener must be determined, partly to help in the discovery of further compounds within the same class. However, mounting regulatory and economic pressure has changed the industry completely, making it harder to find a successful herbicide. Herbicide resistance has also become a major problem, increasing the difficulty of controlling weeds. As a result, the development of new molecules has become a rare event today.Modern industrial herbicide research begins with the analysis and definition of research objectives. A major part of this lies in the definition of economically important weeds in major arable crops (Kraehmer, 2012). Weed associations change slowly over time. It is important, therefore, to foresee such changes. Today’s weed associations result from events in the distant past. They are associated with the history of crops and the evolution of farm management. In Europe and the Americas, some large-acre crops such as winter oilseed rape and spring oilseed rape (canola), both derived from Brassica spp., and soybean (Glycine max) have attained their current importance only within the last 100 years. Other Old World crops, such as cereals, have expanded over a very long time span and were already rather widespread in Neolithic times (Zohary et al., 2012). The dominance of crop species in agricultural habitats only left room for weed species that could adapt to cultivation technologies. Changes in crop management and the global weed infestation have happened in waves. A major early factor in Europe was presumably the grain trade in the Roman period (Erdkamp, 2005). The Romans spread their preferred crops and, unintentionally, associated weed seeds throughout Europe, Asia, and Africa. A second wave of global vegetation change started in the 16th century after the discovery of the Americas. Crops and weeds were distributed globally by agronomists and botanists. Alien species started to spread on all continents. A third phase can be seen in the 19th century with the industrialization of agriculture and the breeding of competitive crop varieties. The analysis of weed spectra in arable fields grew from this historical background. Weeds are plants interfering with the interests of people (Kraehmer and Baur, 2013), which is why they have been controlled by farmers for millennia.Chemical weed control began just about a century ago with a few inorganic compounds, such as sulfuric acid, copper salts, and sodium chlorate (Cremlyn, 1991). The herbicidal activity of 2,4-dichlorophenoxyacetic acid was detected in the 1940s (Troyer, 2001). Büchel et al. (1977) and Cremlyn (1991), Worthington and Hance (1991). Targeted herbicide research began in the 1950s. In the early days, herbicide candidates progressed from screens purely on the basis of their having biology that would satisfy farmers’ requirements. Mode of action (MoA) studies did not play a major role in the chemical industry prior to the 1970s. Analytical tools were developed and the rapid elucidation of plant pathways and in vitro-based screen assays were used from the 1980s onward. However, in the 1990s and beyond, ever-increasing regulatory and economic pressures have changed the situation of the industry completely, and to satisfy the new requirements, selection criteria beyond biological activity have needed to be applied. Herbicide resistance in weeds has developed into a more serious problem that now constrains the application of certain types of herbicides in some markets. Finally, the introduction of crops resistant to cheap herbicides and of glyphosate-resistant soybean, in particular, took value out of the market and resulted in an enormous economic pressure on the herbicide-producing industry. As a result of this changing and more difficult landscape, the development of new molecules is now a rare event.

Table I.

History of chemical weed control innovationsPost, Postemergence application; Pre, preemergence application, based on data from Cremlyn (1991), Worthington and Hance (1991), Büchel et al. (1977), Herbicide Resistance Action Committee (www.hracglobal.com), and others.

Biocatalyzed approach for the surface functionalization of poly(L‐lactic acid) films using hydrolytic enzymes

Poly(lactic acid) as a biodegradable thermoplastic polyester has received increasing attention. This renewable polyester has found applications in a wide range of products such as food packaging, textiles and biomedical devices. Its major drawbacks are poor toughness, slow degradation rate and lack of reactive side‐chain groups. An enzymatic process for the grafting of carboxylic acids onto the surface of poly(L‐lactic acid) (PLLA) films was developed using Candida antarctica lipase B as a catalyst. Enzymatic hydrolysis of the PLLA film using Humicola insolens cutinase in order to increase the number of hydroxyl and carboxylic groups on the outer polymer chains for grafting was also assessed and showed a change of water contact angle from 74.6 to 33.1° while the roughness and waviness were an order of magnitude higher in comparison to the blank. Surface functionalization was demonstrated using two different techniques, ¹⁴C‐radiochemical analysis and X‐ray photoelectron spectroscopy (XPS) using ¹⁴C‐butyric acid sodium salt and 4,4,4‐trifluorobutyric acid as model molecules, respectively. XPS analysis showed that 4,4,4‐trifluorobutyric acid was enzymatically coupled based on an increase of the fluor content from 0.19 to 0.40%. The presented ¹⁴C‐radiochemical analyses are consistent with the XPS data indicating the potential of enzymatic functionalization in different reaction conditions.     

DNS-Gehalt und Chromosomenstruktur bei Amphibien

Comparative karyotype analysis and cytophotometric DNA measurements on further amphibian species (Hyla arborea, Bombina variegata, B. bombina, Triturus vulgaris, T. alpestris, and Salamandra salamandra) were carried out. The relative DNA values of the genomes determined for these species and other amphibians investigated earlier (Ullerich, 1966, 1967), already do nearly exclude the hypothesis that the interspecific differences in DNA content in frogs, toads, and salamanders are caused by differential polynemy of their chromosomes. Electron microscopic investigations on the DNA axes of lampbrush chromosomes of Bufo calamita, B. viridis, B. bufo, Rana esculenta, Bombina variegata, and Triturus alpestris treated with trypsin and ribonuclease confirm that the chromosomes of these species are not polynemic; in all species analysed the lampbrush chromosomes consist of the same number of DNA strands. The double-strandedness observed regularly in several segments of the chromatid axes in the loops as well as in the interchromomeric regions of all species suggest that the chromatids possibly are divided into half-chromatids. The minimum diameter of these two deoxyribonuclease-sensitive fibrills is 20–35 Å, whereas the chromatid axes in those segments which do not show double-strandedness mostly measure 40–65 Å. The high DNA amounts and interspecific differences in DNA content in the amphibian species analysed, probably in all amphibians, therefore must be caused during evolutionary processes by local increase (perhaps in a smaller extent also by-local decrease) in DNA in the chromosomes.     

Analysis of a recessive mutation on the Y chromosome of the fly Caliphora erythrocephala

Summary In a strain of the mutantw (yellow eye colour, sex-linked and sex-limited to the females) ofCalliphora erythrocephala yellow-eyed males have been found. In connexion with the mechanism of sex-determination in this fly, their origin is explained by an alteration on the Y-chromosome (one of the III^rd large chromosomes) in form of either a pre-meiotic cross-over or a spontaneous mutation on thew ⁺-locus. For being recessive, it can become manifest only in thew strain.     

Die genetische Grundlage der Monogenie bei der Schmei?fliege Chrysomya rufifacies (Calliphoridae, Diptera)

Summary Recently in our wild stock of the monogenic blowfly Chrysomya rufifacies a recessive mutation white (w) causing white instead of red-brown eyes spontaneously appeared (Fig. 1). This marker gene enabled us to clarify the genetic basis of monogeny in this species. F₁ offspring produced by reciprocal crossings between normal (+/+) and white-eyed (w/w) flies were phenotypically wildtype (Table 1). In F₂ offspring of female-producing (thelygenic) and male-producing (arrhenogenic) F₁ females wildtype and white-eyed flies appeared in the expected 3:1 ratio; in several crossings a slight deviation of this ratio indicated a reduced viability of the w/w individuals (Table 2). Examination of F₂ progeny of thelygenic F₁+/w females, which had received the w allele from their father, showed that most of the F₂+/+ females were thelygenic, whereas most of the F₂ w/w females were arrhenogenic; among F₂+/w females thelygenic and arrhenogenic individuals occurred in almost equal numbers (Table 3). On the other hand, when F₂ offspring of thelygenic F₁+/w females which had inherited the w allele from their mother were tested, most of the F₂+/+ females turned out to be arrhenogenic and most of the F₂ w/w females thelygenic; among F₂+/w females thelygenic and arrhenogenic flies also were found in almost equal frequencies (Table 4). the sex-linked inheritance of the factor w following from these results was also confirmed by an analysis of the progeny of thelygenic F₁+/w females backcrossed with w/w males. Among the R₁ offspring of F₁+/w females, which had received the w allele from their father, the +/w females were predominantly thelygenic compared to their predominantly arrhenogenic w/w sisters (Table 5). Analysis of R₁ progeny of F₁+/w females, which had inherited the w allele from their mother, yielded reciprocal results (Table 6).This mode of incomplete sex-linkage of the mutation white observed in C. rufifacies (Figs. 2–5) supports the hypothesis that thelygenic females are heterozygous for a dominant female sex realizer (F') with predetermined sex-determining properties, and that arrhenogenic females as well as the males are homozygous for the recessive allele f (Fig. 6). The recombination frequency between F'/f and the w-Locus was calculated to be 12.72±0.72 per cent.

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