Cytochemical investigation of genic male-sterility in Chinese cabbage

A genic male sterile Chinese cabbage, Brassica campestris L. ssp. chinensis Makino, was examined using cytological and cytochemical methods to characterize the process of pollen abortion in this plant. Thick sections of both fertile and sterile anthers at different developmental stages were stained using Toluidine Blue O, Periodic Acid-Schiff’s (PAS) reaction and Sudan Black B to detect cytochemical changes that may occur in the distribution of insoluble polysaccharide and lipid storage bodies. Pollen abortion in sterile anthers occurs at an early stage of microspore development. During early microspore development, reductions in the number of starch grains in the connective tissue of fertile anthers coincide with the accumulation of starch grains in cells of the anther wall. In the late microspore stage, a large vacuole forms in the microspore, and tapetal cells synthesize and accumulate lipid droplets. The cellular organization of tapetal cells in sterile anthers appears similar to that in fertile anthers, except for the absence of lipid droplets in cells of sterile anthers and diffusely labeled tapetal polysaccharides, suggesting defects in nutrient storage. Supported by National Natural Science Foundation of CHINA (30170060)     

Fatal Attraction of Short-Tailed Shearwaters to Artificial Lights

Light pollution is increasing around the world and altering natural nightscapes with potential ecological and evolutionary consequences. A severe ecological perturbation caused by artificial lights is mass mortalities of organisms, including seabird fledglings that are attracted to lights at night on their first flights to the sea. Here, we report on the number of fledging short-tailed shearwaters Ardenna tenuirostris found grounded in evening and morning rescue patrols conducted at Phillip Island, Australia, during a 15-year period (1999–2013). We assessed factors affecting numbers of grounded birds and mortality including date, moon phase, wind direction and speed, number of visitors and holiday periods. We also tested experimentally if birds were attracted to lights by turning the lights off on a section of the road. Of 8871 fledglings found, 39% were dead or dying. This mortality rate was 4–8 times higher than reported elsewhere for other shearwater species, probably because searching for fledglings was part of our systematic rescue effort rather than the opportunistic rescue used elsewhere. Thus, it suggests that light-induced mortality of seabirds is usually underestimated. We rescued more birds (dead and alive) in peak fledging, moonless and windy nights. Mortality increased through the fledging period, in the mornings and with increased traffic on holiday periods. Turning the road lights off decreased the number of grounded birds (dead and alive). While moon, wind and time are uncontrolled natural constraints, we demonstrated that reduction of light pollution and better traffic management can mitigate artificial light-induced mortality.     

Population trends in a substantial colony of Little Penguins: three independent measures over three decades

Estimating long-term population trends is vital for the conservation and management of species, yet few trends exist and fewer still are verified with independent measures. We compared three independent measures of change in population size over 27 years (1984–2011) for a significant Little Penguin Eudyptula minor colony in south-eastern Australia: (1) a series of 13 colony-wide surveys conducted in eight separate years, (2) mean nightly counts of penguins returning to breeding sites (365 counts × 27 years) and (3) population growth rates from a demographic model based on survival and recruitment rates measured at three sites each year. Colony-wide surveys of burrows were used as a benchmark of change in population size in the 8 years they were conducted as they were a robust measure of population size corrected for intra-annual variation in burrow occupancy using mark-recapture modelling at six reference sites. However, the demographic model matched the trend from colony-wide surveys with greater resolution in years and with less effort. Beach counts were unreliable for monitoring trends for the entire population due to its singular and peripheral location in the colony. Trends indicate a doubling of the population from 1984 to 2011 despite a marked population contraction linked to a mass mortality of a key prey species. The colony appears secure but remains subject to changes in the marine and terrestrial environments in the longer term.     

Molecular dissection of the epsilon subunit of the chloroplast ATP synthase of spinach.

The gene encoding the epsilon subunit (atpE) of the chloroplast ATP synthase of Spinacia oleracea has been overexpressed in Escherichia coli. The recombinant protein can be solubilized in 8 M urea and directly diluted into buffer containing ethanol and glycerol to obtain epsilon that is as biologically active as epsilon purified from chloroplast-coupling factor 1 (CF1). Recombinant epsilon folded in this manner inhibits the ATPase activity of soluble and membrane-bound CF1 deficient in epsilon and restores proton impermeability to thylakoid membranes reconstituted with CF1 deficient in epsilon. Site-directed mutagenesis was used to generate truncations and single amino acid substitutions in the primary structure of epsilon. In the five mutants tested, alterations that weaken ATPase inhibition by recombinant epsilon affect its ability to restore proton impermeability to a similar extent, with one exception. Substitution of histidine-37 with arginine appears to uncouple ATPase inhibition and the restoration of proton impermeability. As in the case of E. coli, it appears that N-terminal truncations of the epsilon subunit have more profound effects than C-terminal deletions on the function of epsilon. Recombinant epsilon with six amino acids deleted from the C terminus, which is the only region of significant mismatch between the epsilon of spinach and the epsilon of Pisum sativum, inhibits ATPase activity with a reduced potency similar to that of purified pea epsilon. Four of the six amino acids are serine or threonine. These hydroxylated amino acids may be important in epsilon-CF1 interactions.     

Hypercholesterolemia in five Israeli Christian-Arab kindreds is caused by the “Lebanese” allele at the low density lipoprotein receptor gene locus and by an additional independent major factor

Summary Segregation analyses were performed for plasma low density lipoprotein cholesterol (LDL-C), triglycerides (TG) and high density lipoprotein cholesterol (HDL-C) in five Christian Arab kindreds identified through probands with familial hypercholesterolemia. In this subset of the Christian Arab community, the results were consistent with major gene determination of LDL-C with allele frequency (q) of 0.042 (95% confidence interval 0.008–0.079) in addition to polygenic transmission (h ²= 0.34). The Lebanese allele was identified directly by polymerase chain reaction and HinfI restriction analysis. Analysis of this mutation permits direct diagnosis of familial hypercholesterolemia in most affected individuals although our results indicated the possible existence of an additional independent factor leading to elevated LDL-C levels. The segregation results for TG indicated the presence of a major effect, although the existence of a major gene could not be demonstrated. There was also no evidence of a major locus effect on HDL-C levels.     

Decline of activity and quantity of ribulose bisphosphate carboxylase/oxygenase and net photosynthesis in ozone-treated potato foliage

The effect of ozone (O₃) on ribulose bisphosphate carboxylase/oxygenase (Rubisco) activity and quantity and net photosynthesis in greenhouse-grown Solanum tuberosum L. cv `Norland' foliage was studied in relation to oxidant-induced premature senescence. Plants, 26 days old, were exposed to 0.06 to 0.08 microliters per liter O₃ from 1000 to 1600 hours for 4 days in a controlled environment chamber. On day 5, plants were exposed to a 6-hour simulated inversion in which O₃ peaked at 0.12 microliters per liter. Net photosynthesis declined in response to O₃ but recovered to near control levels 3 days after the exposure ended. Rubisco activity and quantity in control potato foliage increased and then decreased during the 12-day interval of the study. In some experiments foliage studied was physiologically mature and Rubisco activity had peaked when O₃ exposure commenced. In those cases, O₃ accelerated the decline in Rubisco activity. When less mature foliage was treated with O₃, the leaves never achieved the maximal level of Rubisco activity observed in control foliage and also exhibited more rapid decline in initial and total activity. Percent activation of Rubisco (initial/total activity) was not affected significantly by treatment. Quantity of Rubisco decreased in concert with activity. The decrease in activities is most likely due to a decrease in available protein rather than a decrease in the percentage of Rubisco activated in vivo. The reduction in the quantity of Rubisco, an important foliar storage protein, could contribute to premature senescence associated with toxicity of this air pollutant.     

The specificity of the S1 subsite of papain

The specificity of the S(1)' subsite of the proteolytic enzyme papain was investigated by studying the effect of l-alpha-amino acid amides on the enzyme-catalysed hydrolysis of N-benzyloxycarbonylglycine p-nitrophenyl ester and by determining the kinetic parameters for the enzyme-catalysed hydrolysis of some N-benzyloxycarbonylglycyl-l-amino acid amides. These studies showed that the S(1)' subsite has a predilection for hydrophobic residues, in particular l-leucine and l-tryptophan. The specificity for these residues is manifest in both the binding and acylation steps. N-Benzyloxycarbonylglycine amide is not hydrolysed under comparable conditions, indicating that the amide group adjacent to and on the C-terminal side of the peptide bond about to be cleaved makes an important contribution to the rate of the papain-catalysed hydrolysis of peptides.     

DIPI and DAPI: Fluorescence banding with only negligible fading

Summary DIPI and DAPI produce distinct fluorescent bands in human chromosomes similar to quinacrine banding patterns. Additionally, the AT rich secondary constrictions in the chromosomes Nos. 1, 9 and 16 are brightly fluorescent. On the other hand the brilliantly fluorescent regions after staining with quinacrine mustard in the chromosomes Nos. 3 and 4, satellites and some other regions in the acrocentric chromosomes are less striking. The distal part of the Y, however, is clearly discernible. Thus DIPI and DAPI seem to be strictly AT specific fluorochromes like Hoechst 33258.In interphase nuclei the Y chromosome can be identified. However, quinacrines are superior for Y-body analysis in buccal, hair cell and sperm smears.BrdU labeled chromatids show reduced fluorescence intensity. The difference, however, is less apparent than after staining with Hoechst 33 258.DAPI and especially DIPI are highly resistant to UV-irradiation; there is almost no fading within 30 min when using DIPI. Moreover, fluorescence intensity is stronger than in quinacrines. When photographing, exposure times may be reduced to about one quarter compared to quinacrine mustard.     

Corvids congregate to breeding colonies of a burrow‐nesting seabird

Egg predation is a major cause of reproductive failure among birds, and can compromise the viability of affected populations. Some egg predators aggregate near colonially breeding birds to exploit the seasonal increase of prey resources. We investigated spatial and temporal variations in the abundance of an egg predator (little raven Corvus mellori; Corvidae) to identify whether ravens aggregate spatially or temporally to coincide with any of three potential prey species: burrow‐nesting little penguin (Eudyptula minor; Spheniscidae), short‐tailed shearwater (Ardenna tenuirostris; Procellariidae), and surface‐nesting silver gull (Chroicocephalus novaehollandiae; Laridae). We derived spatially explicit density estimates of little ravens using distance sampling along line transects throughout a calendar year, which encompassed little penguin, short‐tailed shearwater and silver gull breeding and non‐breeding seasons. High raven abundance coincided temporally with penguin and gull egg laying periods but not with that of shearwaters. The spatial distribution of raven density corresponded with the little penguin colony but not with shearwater or gull colonies. Thus, the presence of little penguin eggs in burrows correlated strongly with little raven activity, and this implies that little ravens may have learnt to exploit the plentiful subsurface food resource of little penguin eggs. Corvid management may be required to maintain the viability of this socially and economically important penguin colony.