Skinny hedgehog, an acyltransferase required for palmitoylation and activity of the hedgehog signal

One of the most dominant influences in the patterning of multicellular embryos is exerted by the Hedgehog (Hh) family of secreted signaling proteins. Here, we identify a segment polarity gene in Drosophila melanogaster, skinny hedgehog (ski), and show that its product is required in Hh-expressing cells for production of appropriate signaling activity in embryos and in the imaginal precursors of adult tissues. The ski gene encodes an apparent acyltransferase, and we provide genetic and biochemical evidence that Hh proteins from ski mutant cells retain carboxyl-terminal cholesterol modification but lack amino-terminal palmitate modification. Our results suggest that ski encodes an enzyme that acts within the secretory pathway to catalyze amino-terminal palmitoylation of Hh, and further demonstrate that this lipid modification is required for the embryonic and larval patterning activities of the Hh signal.     

Antithrombin 3. Protection against death after injection of thromboplastin

Intravenous injection of autologous lipoprotein (thromboplastin) or thrombin produced a lethal, hemorrhagic syndrome in chicken embryos. The embryos could be protected from this fatal result by injection of antithrombin III, an alpha(2)-globulin (molecular weight 60,000 to 80,000) purified from human, bovine, and guinea pig blood. Heparin also protected the embryos, but other inhibitors were less protective.     

The silage yield potential of hybrid ryegrass over a 5-year period in Northern Ireland relative to other ryegrasses and timothy

The yield and persistency of grass species within a managed sward are a major consideration when determining species mixtures for either long-term or short-term sward management systems. Perennial ryegrass is lower yielding but more persistent than Italian ryegrass. Hybrid ryegrass, an interspecies cross between perennial and Italian ryegrass, may be higher yielding than perennial ryegrass and more persistent than Italian ryegrass. Therefore, the yield and persistency of hybrid ryegrass was investigated in Northern Ireland in five experiments, each harvested over five consecutive years, and compared with that of Italian ryegrass, perennial ryegrass and timothy. The performance of the five grass species were in the expected order; Italian ryegrass was higher yielding than hybrid ryegrass, which was higher than perennial ryegrass, with timothy the lowest, whereas perennial ryegrass and timothy had significantly higher sward densities than the hybrid and Italian ryegrasses. In addition, it was found that the rate of decline in yield and sward density with age was the same for all species. Consequently, this study indicated that the higher yielding Italian and hybrid ryegrasses could continue to out-perform perennial ryegrass for 5 years, opening the possibility of more extensive farming use of these species, particularly in Northern Ireland.     

The cooling of potatoes packed in hessian and in paper sacks

Summary By determining the germinating power of potatoes of the Bintje variety it could be clearly demonstrated that seed potatoes (also when stored without sprouts at 2 C)-undergo changes in their germinating power and exhibit senility symptoms about twelve months after being harvested.

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Zusammenfassung Durch die Bestimmung der Keimf?higkeit von Kartoffeln der Sorte Bintje konnte deutlich nachgewiesen werden, dass bei Saatkartoffeln (auch wenn ungekeimt lagernd bei 2 C) Ver?nderung ihrer Keimf?higkeit eintritt und 1 Jahr nach der Ernte Alterserscheinungen zutage treten.

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Resume En déterminant le pouvoir germinateur de pommes de terre de la variété Bintje, on a pu prouver d'une fa?on évidente que les plants de pommes de terre (même si elles sont conservées à une température de 2 C, exempts de gérmes) changent dans leur faculté germinative, tout en démontrant des phénomènes de vieillesse un an environ après avoir été récoltées.

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Ditton Laboratory, Department of Scientific and Industrial Research     

Molecular data from up to 130-year-old herbarium specimens do not support the presence of cherry powdery mildew in Australia

A strain of Podosphaera clandestina has been highlighted as a priority pest threat to the Australian cherry industry. Australia currently has no records of powdery mildew on cherry (Prunus avium). P. clandestina is reported to cause disease on a range of Rosaceae genera including Crataegus and Prunus; in Australia, P. clandestina has only been recorded on Crataegus. A recent species revision identified Podosphaera cerasi on P. avium as a separate species from P. clandestina. Therefore, a revision of which powdery mildew species is present in Australia on Crataegus is required to inform Australian plant biosecurity. Reference collection specimens from the Victorian Plant Pathology Herbarium (VPRI) recorded as Podosphaera spp. collected between 1889 to 2008 on cherry and three other host plant genera from Australia and overseas were sampled for DNA extraction and next-generation sequencing (NGS). Sequence data from preserved specimens were successfully mapped to internal transcribed spacer (ITS) sequences of P. clandestina in the strict sense, P. cerasi, and Podosphaera prunicola, and chloroplast matK sequences were used to identify plant hosts. Australian specimens on Crataegus hosts were P. clandestina in the strict sense and specimens on Prunus from the USA were identified as P. cerasi and P. prunicola. The outcome of this study confirmed the powdery mildew on Australian Crataegus specimens to be P. clandestina and none of the cherry powdery mildews (Podosphaera pruni-avium, P. cerasi, or P. prunicola) are present on Australian specimens in the VPRI collection, which suggests they are not present in Australia.     

Pregnancy rates during experimentation in dairy cows

This study investigated pregnancy rates on day 16 in dairy cows following artificial insemination and blood sampling to monitor hormonal status. Collection of blood samples by jugular venepuncture coupled with single fixed time insemination resulted in a poor pregnancy rate (27.8%). Modification of the protocol to include double insemination and collection of blood samples from jugular cannulae inserted four days prior to insemination did not improve pregnancy rate (27.3%). Acclimatization of cows to the experimental facility, however, resulted in a dramatic increase in pregnancy rate (85.7%;P < 0.005). This improvement was not associated with any difference in plasma progesterone but was associated with a marked advancement in the decline in oestradiol at the end of the follicular phase, indicative of earlier ovulation. Non-pregnancy was associated with a delayed fall in oestradiol and reduced plasma concentrations of progesterone. The results support a role for inadequate progesterone in early embryo mortality but suggest that impaired ovulation is a more important problem in cows under the 'stress' of experimentation.     

Timing of follicular phase events and the postovulatory progesterone rise following synchronisation of oestrus in cows

In cows the timing of both ovulation and the subsequent postovulatory progesterone rise are critical to successful fertilisation and early embryo development. The aim of this study was to determine the degree of variability in the timing of ovulation relative to other follicular phase events and to determine how variations in the timing of follicular phase events contribute to the timing of the postovulatory progesterone rise. Plasma concentrations of progesterone, oestradiol and luteinising hormone (LH) and the timing of oestrus and ovulation were determined following induction of luteolysis were determined in 18 mature, non-lactating Holstein-Friesian cows. Four cows were excluded on the basis of abnormal reproductive function. In the remaining 14 cows oestrus occurred at 57.4+/-4.3h and the LH surge at 54.6+/-4.0h following luteolysis (progesterone <1ngmL(-1)) followed by a fall in circulating oestradiol concentration at 64.6+/-4.4h. Cows ovulated at 88.0+/-4.7h with the postovulatory progesterone rise (to >1ngmL(-1)) occurring 159+/-7.2h after luteolysis. There was considerable variation in the timing of ovulation following luteolysis (range 64-136h) onset of oestrus (range 24-40h) and onset of the LH surge (range 24-44h). Cows were then split on the basis of interval from progesterone fall to progesterone rise giving groups (n=7 per group) with intervals of 180.6+/-6.7 and 138.3+/-5.7h (P<0.001). Between groups, both the intervals from luteolysis to ovulation (98.3+/-6.9 vs 77.7+/-3.4h; P<0.05) and ovulation to progesterone rise (82.3+/-4.2 vs. 60.6+/-5.5h; P<0.01) were longer in late rise cows. There was no difference between groups in the interval from oestrus or LH surge to ovulation. In conclusion the results of this study further highlight the high variability that exists in the timing and interrelationships of follicular phase events in the modern dairy cow, reemphasising the challenges that exist in optimising mating strategies. However, the data do suggest that in cows with poor post ovulatory progesterone secretion, the key problem appears to be poor post ovulatory development rather than a delay in ovulation.