Resolving the genetic basis of invasiveness and predicting invasions

Considerable effort has been invested in determining traits underlying invasiveness. Yet, identifying a set of traits that commonly confers invasiveness in a range of species has proven elusive, and almost nothing is known about genetic loci affecting invasive success. Incorporating genetic model organisms into ecologically relevant studies is one promising avenue to begin dissecting the genetic underpinnings of invasiveness. Molecular biologists are rapidly characterizing genes mediating developmental responses to diverse environmental cues, i.e., genes for plasticity, as well as to environmental factors likely to impose strong selection on invading species, e.g., resistance to herbivores and competitors, coordination of life-history events with seasonal changes, and physiological tolerance of heat, drought, or cold. Here, we give an overview of molecular genetic tools increasingly used to characterize the genetic basis of adaptation and that may be used to begin identifying genetic mechanisms of invasiveness. Given the divergent traits that affect invasiveness, “invasiveness genes” common to many clades are unlikely, but the combination of developmental genetic advances with further evolutionary studies and modeling may provide a framework for identifying genes that account for invasiveness in related species.     

三个玉米合成群体选系的配合力及杂种优势分析

采用NCⅡ遗传交配设计,通过在黑龙江省哈尔滨和泰来的两点试验,以玉米自交系Mo17、B73、444和丹340为测验种,对从群体品综1号、中综3号和陕综5号选育的18份自交系进行配合力及杂种优势分析,以探讨群体选系在我国东北早熟玉米区的利用途径。结果表明,供试自交系间一般配合力存在较大差异;陕综5号群体选系HR14、HR17和HR15、中综3号选系HR9和HR8、品综1号选系HR4的一般配合力较高。在供试的72个组合中HR15×丹340、HR17×丹340、HR9×Mo17、HR14×丹340、HR7×B73、HR8×B73、HR6×444、HR5×丹340产量的特殊配合力及对照优势较高,表现出较高的利用潜力。依据特殊配合力及对照优势分析,中综3号选系与旅大红骨群、陕综5号选系与兰卡斯特群、品综1号选系与瑞德群遗传关系较近。结合育种实践,在我国北方早熟春玉米区陕综5号×旅大红骨、中综3号×瑞德或兰卡斯特、品综1号×旅大红骨或唐四平头可能组成较大利用潜力的杂种优势模式。     

The use of killer sensitivity patterns for biotyping yeast strains: the state of the art, potentialities and limitations

In recent years molecular techniques have been the most useful tools for the unequivocal identification of undetermined strains at the species level. In many instances, however, a further discrimination at the strain level (biotyping) is required, such as during epidemiological investigations, in which the distribution of pathogenic microorganisms is studied, and for patent protection purposes. Although molecular methods are routinely used also for yeast biotyping, several nonmolecular techniques have been proposed. One of these, the determination of the killer sensitivity pattern (KSP) towards a panel of selected killer toxins has proven to be a good auxiliary method. Despite the plethora of studies published, the potential and limitations of the determination of KSPs have never been critically evaluated. In this review the use of this nonmolecular technique as a biotyping tool is discussed and compared with some currently used DNA-based procedures. In addition, methodological, mechanistic and ecological implications are evaluated.     

Direct and indirect impacts of wildfire on faunal communities of Mediterranean temporary ponds

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Discrimination between extreme chronotypes using the full and reduced version of the Morningness-Eveningness Questionnaire

The aim of this study was to carry out a comparison of the ability to discriminate between extreme chronotypes, i.e., morning- and evening-types, among the Morningness-Eveningness Questionnaire (MEQ) and its reduced version (rMEQ). To this end a secondary analysis of cohort studies, using two different approaches, was carried out. The first, subjective, relied on the computing of overlap between extreme chronotypes according to their hourly ideal bedtime, get-up time and midpoint of sleep reported at the MEQ and rMEQ, while the second, objective, on the corresponding actual-actigraphic times. At the subjective approach, 2706 participants filled in the MEQ, while 940 the rMEQ (age range of both groups: 18–30 years). The overlap was significantly lower among those who filled the rMEQ than MEQ when considering ideal midpoint of sleep (13.70% and 46.28%, respectively) and get-up time (47.04% and 62.34%, respectively). At the objective approach, 51 participants filled in the MEQ while 52 the rMEQ (age range: 19–30 years in both groups) at the end of one week of actigraphic recording. No significantly different overlap across those who filled the MEQ or rMEQ was observed with reference to the examined actigraphic times. Results of subjective assessment showed as rMEQ more clearly discriminated between extreme chronotypes than MEQ. The attempt to find an objective confirmation did not provide the same results, probably as a consequence of a masking effect by social rhythms.     

利用SNP标记及配合力划分超甜玉米自交系的杂种优势群

划分超甜玉米自交系的杂种优势群,筛选配合力高的甜玉米自交系,构建新的杂种优势更强的甜玉米群体,为优良甜玉米的选育提供依据.本研究选用23个自育超甜玉米自交系,采用NC Ⅱ设计得到60(3×20)个组合,研究它们的产量配合力效应并结合56K SNP标记将供试材料进行杂种优势群的划分.结果表明23个自交系的平均杂合率为2....     

Genetic improvement of peanut (Arachis hypogea L.) genotypes by developing short duration hybrids

Peanut, the only cash crop of rainfed areas of Pakistan, is facing immense challenges due to global warming. Climatic factors particularly the temperature fluctuations and rain pattern shift significantly impact the production and yield of peanut and unavailability of resilient varieties exacerbate this impact. To deal with the cropping pattern change and yield losses, due to climate vagaries, a study was conducted to develop early maturing hybrids using line into tester mating design. The F₁ hybrids from the parental lines were produced in the year 2018 using Line × Tester mating design and then grown in the field in the year 2019 for further evaluation. The hybrids were evaluated based on the early maturity and yield-related attributes in comparison with the parental lines. Based on the general combining ability estimate, line V-3 (Golden), was found as best parent with highly significant values for plant height, days to peg formation, days to maturity, number of pegs per plant, number of pods per plants, number of seeds per plant, 100 pod weight 100 seed weight. Similarly, tester V-7 (PI 635006 01 SD) showed highly significant results of GCA for days to germination, day to 50% flowering, plant height, days to peg formation, days to maturity, number of pegs per plant, number of pods per plants, number of seeds per plant, 100 kernel weight, shelling percentage. All the combinations were evaluated for specific combining ability and significant results were observed for V-3 × V-4 (Golden × PI 619175 01 SD) and V-1 × V-6 (BARI-2000 × PI 564846 01 SD) by developing or maturity and yield-related attributes. The hybrid combinations V-3 × V-5 (Golden × PI 635006 01 SD) followed by V-3 × V-6 showed highly significant results for mid parent heterosis and better parent heterosis for days to 50% flowering, plant height, days to peg formation, number of pegs, days to maturity, number of mature seeds per plant, shelling ratio, 100 pod weight and 100 kernel weight. These parents and hybrid combinations with early maturity genes and high yield attributes can further be used for the development of short duration variety.     

Unraveling the essential role in conjugation of the Tra protein of Streptomyces lividans plasmid pIJ101

Plasmid pIJ101 from Streptomyces lividans encodes a single gene, tra, that is essential for both plasmid transfer and mobilization of chromosomes during mating. The tra gene product (Tra) is a membrane protein, a portion of which shows similarity to transfer proteins of other streptomycete plasmids as well as additional bacterial chromosome partitioning proteins. This paper reviews past and present work that has focused on elucidating the precise role of the Tra protein of pIJ101 in conjugation in Streptomyces.     

Abscess forming ability of streptococcus milleri group: synergistic effect with Fusobacterium nucleatum.

The abscess forming abilities of "Streptococcus milleri" strains (Streptococcus constellatus, Streptococcus anginiosus, and Streptococcus intermedius) isolated from dentoalveolar abscesses and the synergistic effect of Fusobacterium nucleatum co-inoculated with the isolates were examined on a mouse subcutaneous abscess model. Five days after inoculation, all S. milleri strains formed abscesses, which showed less pathological spread to surrounding connective tissues than those formed by Staphylococcus aureus 209P strain and were similar to those by F. nucleatum ATCC25586. When each S. milleri strain and F. nucleatum were co-inoculated, abscess sizes and each bacterial number recovered from abscesses increased in comparison to those treated by bacterial mono-inoculation of each S. milleri strain or F. nucleatum alone. The strongest synergistic effect was observed in the combination of S. constellatus and F. nucleatum. In a time course experiment with this combination, the recovery of S. constellatus subsequently decreased after the decrement of F. nucleatum, and it appeared that the association with F. nucleatum maintained the bacterial number of S. constellatus in the abscess. The cell-free supernatant of F. nucleatum had a tendency to increase the abscess size caused by S. constellatus in this model. When S. constellatus was cultured with F. nucleatum culture supernatant in vitro, growth enhancement in the early phase was observed. Furthermore, the phagocytic killing of S. constellatus by human polymorphonuclear leukocytes (PMNs) was significantly suppressed and the PMN membranes appeared to be injured by addition of the F. nucleatum culture supernatant. These results suggest that the pathogenicity of S. milleri strains in odontogenic infections may be enhanced by the co-existence of F. nucleatum.     

Fermentative capacity of baker's yeast exposed to hyperbaric stress

Baker's yeast suspensions were incubated at different pressures (from 1 bar to 6 bar) and different gases [air, O(2) and a mixture of 8% (v/v) CO(2), 21% O(2) and N(2)]. Raising the air pressure from 1 bar to 6 bar stimulated cell growth but had no effect on leavening ability or viability of the cells. A 50% reduction of the CO(2) produced in dough occurred with 6 bar O(2) which also stopped growth. The fermentative capacity of the cells was stimulated by the cells exposure to increased CO(2) partial pressure up to 0.48 bar.