A pear rootstock trial in Israel

The pear cultivars ‘Spadona Estiva’, ‘Coscia’, ‘Beurré Superfin’ and a ‘Bartlett’ clone of South African origin (termed ‘Bartlett Sport’) were tested on 5 quince rootstock types, 5 Pyrus species and on 5 or 30 cm long interstocks of the pear cultivars ‘Bergamotte Esperen’ and ‘Spadona Estiva’ on quince MA, while ‘Dr. Jules Guyot’ was used as an interstock on ‘Bartlett’ seedlings.At the age of 10 years only ‘Spadona Estiva’ showed no signs of decline on quince rootstocks, ‘Coscia’ showed moderate decline, while the remaining cultivars had already declined severely. When the trunk circumference of ‘Beurré Superfin’ trees on the various quince clones was taken as an indicator for the degree of graft incompatibility, a negative correlation was found between this parameter and cyanogenic glycoside content in the stem bark of ungrafted quince plants belonging to the same clones. Pear interstocks on quince MA rootstocks did in some cases increase crops compared to the same quince alone, but did not prevent the decline of ‘Beurré Superfin’ and Bartlett Sport' on quince.The most vigorous and most prolific rootstock was Pyrus betulaefolia. However, with ‘Spadona Estiva’ differences in vigor between the rootstocks were only small and crops on the Israeli quince CI 7 were similar to those on Pyrus betulaefolia, but fruit size was larger on quince. Cropping of this cultivar at the age of 4 years was closely related to the intensity of flowering, whereas with ‘Coscia’ this relation was much less evident.Leaf fall in autumn and the opening of the vegetative buds of ‘Beurré Superfin’ in spring were earlier on quince than on Pyrus rootstocks.     

Effect of gradual acclimation to high ambient temperatures on egg‐shell quality of the Sinai Bedouin fowl,the commercial white leghorn and their crossbreds

1. The effect of gradual acclimation to high ambient temperatures on egg‐shell quality was studied in the Sinai fowl, the commercial White Leghorn, and their reciprocal crossbreds.

2. The Leghorn egg was characterised by a thinner and weaker shell compared with the Sinai and the crossbreds, at all the experimental temperatures.

3. In contrast to other reports, high ambient temperatures for a long period had only mild effects on egg‐shell quality.

4. The results suggest that gradual acclimation to high ambient temperatures might improve the efficiency of the physiological mechanisms involved in the hen's response to heat. Consequently, the reproductive process adapts to the hot environmental conditions.

5. The results indicate that the Sinai breed might be used for future selection of a breed, highly resistant to extreme environmental conditions and with an improved shell quality.     

A yellows disease system with differing principal host plants for the obligatory pathogen and its vector

A stolbur‐type phytoplasma is the putative pathogen of grapevine yellows disease that causes economic damage to vineyards in most growing areas around the world. The pathogen is known to be transmitted to vines by two planthoppers, Hyalesthes obsoletus and Reptalus panzer; the latter is found in Europe but has not yet been observed in Israel. The establishment of a vector–pathogen–plant relationship requires that the pathogen and the vector meet on a shared host plant. This does not happen in the ecosystem examined here, where two different principal host plants for the obligate pathogen and its vector exist: the pathogen is established on vines, while its vector, H. obsoletus, develops on Vitex agnus‐castus. The present study verified that: (i) the vector cannot complete its life cycle on vines; (ii) V. agnus‐castus does not grow in the immediate vicinity of vines, and does not harbour the pathogen; and (iii) the pathogen is not vertically transmitted from mother to offspring. Moreover, in a thorough search of plants in vine growing areas, no other plants were found that host both the vector and the pathogen. However, it was found that the planthopper can acquire the phytoplasma from infected vines. Nonetheless, this does not prove the ability of the planthopper to further transmit the pathogen to vines and does not explain the presence of the vector on the non‐preferred vines. Thus, the enigma of the pathogen–vector–host triangle in this system remains unresolved.     

Egg‐shell water Vapour conductance of the domestic fowl: Comparison between two breeds and their crosses

1. A comparison of egg water loss and egg‐shell water vapour conductance was made between the Sinai fowl (a desert inhabiting breed) and the commercial White Leghorn, together with their reciprocal crossbreds.

2. The Sinai egg was found to be smaller and less permeable to water vapour than the eggs of the Leghorn and crossbreds. The differences were statistically significant.

3. The measured egg‐shell water vapour conductance of the Sinai breed was 25% lower than predicted on the basis of egg mass.

4. The low permeability of the Sinai egg shell might be related to its higher than predicted thickness, which did not interfere with the shell functional pore area.

5. The low water vapour conductance of the Sinai egg shell may reflect adaptations to its dry habitat.     

Differences in egg‐shell quality among the Sinai Bedouin fowl,the commercial white leghorn and their crossbreds

1. A comparison of egg‐shell characteristics was made among the Sinai breed (a desert inhabiting strain), the commercial White Leghorn and their reciprocal crossbreds.

2. The Sinai egg was smaller and its shell thicker and stronger than the Leghorn egg. All the differences were statistically significant.

3. Shell thickness and strength of Leghorn eggs were in accordance with values predicted on the basis of egg mass, while those of the Sinai and the two crosses were considerably higher than predicted.

4. The apparent differences in mean egg mass between Sinai and Leghorn breeds did not explain the differences in egg‐shell quality, neither did the shape index which was very similar among all breeds.

5. The findings suggest that the differences in egg‐shell properties are of a genetic origin.

6. The thick, strong and less permeable egg‐shell of the Sinai breed may reflect adaptations to its arid environmental origin and to incubation in the open.

7. These genetically‐determined egg‐shell characteristics might serve in a future selection for improved egg‐shell quality in poultry.     

Effect of acute heat exposure on blood flow and its distribution in the unrestrained laying fowl (Gallus domesticus)

1. The effect of heat exposure (air temperature 35–45°C) for 1.5 h on blood flow distribution between the abdominal viscera and the muscles of abdominal wall and hind leg was investigated in unanaesthetised, unrestrained laying fowl.

2. Heat stressed fowl showed a significant hyperthermia (+ 1.3°C), rapid shallow breathing (229 breaths/min) and significant hypocapnia ( ? 8 Torr).

3. Significant increases in absolute blood flow (ml/g per min) were measured in the kidneys, spleen, liver and duodenum during hyperthermia, but there was no change in the absolute blood flow to the reproductive tract or the relative perfusion of the reproductive tract compared with the other tissues sampled.

4. We conclude that in these acute conditions of heat exposure, blood flow to the reproductive tract of the laying fowl is not compromised by any simultaneous thermoregulatory needs.     

Effect of acute heat exposure on triglyceride transfer to the preovulatory follicles of the laying fowl (Gallus Domesticus)

1. The effect of acute heat exposure on triglyceride (TG) transfer to preovulatory follicles was studied in the laying fowl.

2. Heat exposure of laying fowl resulted in a 1.1°C rise in body temperature, a 10‐fold increase in respiration frequency and mild hypocapnia and hypoxaemia.

3. Plasma and follicular tissue TG concentrations were not significandy affected by heat exposure, but plasma TG specific radioactivity decreased significantly and was negatively correlated with body temperature.

4. The transfer rate of TG to the preovulatory follicles was not affected significantly by hyperthermia.

5. We conclude that nutrient supply to the developing follicles is not compromised in acutely heat‐exposed laying fowl.     

Complexes of Cu–Polysaccharide of a Marine Red Microalga Produce Spikes with Antimicrobial Activity

Metal–polysaccharides have recently raised significant interest due to their multifunctional bioactivities. The antimicrobial activity of a complex of Cu₂O with the sulfated polysaccharide (PS) of the marine red microalga Porphyridium sp. was previously attributed to spikes formed on the complex surface (roughness). This hypothesis was further examined here using other Cu–PS complexes (i.e., monovalent-Cu₂O, CuCl and divalent-CuO, CuCl₂). The nanostructure parameters of the monovalent complexes, namely, longer spikes (1000 nm) and greater density (2000–5000 spikes/µm²) were found to be related to the superior inhibition of microbial growth and viability and biofilm formation. When Escherichia coli TV1061, used as a bioluminescent test organism, was exposed to the monovalent Cu–PS complexes, enhanced bioluminescence accumulation was observed, probably due to membrane perforation by the spikes on the surface of the complexes and consequent cytoplasmic leakage. In addition, differences were found in the surface chemistry of the monovalent and divalent Cu–PS complexes, with the monovalent Cu–PS complexes exhibiting greater stability (ζ-potential, FTIR spectra, and leaching out), which could be related to spike formation. This study thus supports our hypothesis that the spikes protruding from the monovalent Cu–PS surfaces, as characterized by their aspect ratio, are responsible for the antimicrobial and antibiofilm activities of the complexes.     

Ontogeny of brain temperature regulation in chicks (Gallus gallus domesticus)

1. Development of brain temperature regulation was studied in the domestic fowl (Gallus gallus domesticus) from hatching to 21 d of age. 2. Body and brain temperature at hatching were relatively low compared with adult levels. However, both were effectively regulated at ambient temperatures of 30 and 35 degrees C, with only a minor difference between the 2 temperatures. 3. Body and brain temperature increased as a power function of age at significantly different rates, approaching adult levels at around 10 d of age and resulting in a linear increase in body-to-brain temperature difference with age. 4. The results indicated the existence of different patterns of post-hatching development of brain temperature regulation in relation to the degree of precocity of a species.