Comment on "Population size does not influence mitochondrial genetic diversity in animals"

Bazin et al. (Reports, 28 April, 2006, p. 570) found no relationship between mitochondrial DNA (mtDNA) diversity and population size when comparing across large groups of animals. We show empirically that species with smaller populations, as represented by eutherian mammals, exhibit a positive correlation between mtDNA and allozyme variation, suggesting that mtDNA diversity may correlate with population size in these animals.     

Zinc uptake and distribution in tomato plants in response to foliar supply of Zn hydroxide‐nitrate nanocrystal suspension with controlled Zn solubility

The present study investigated the foliar uptake rate, distribution, and retranslocation patterns of novel, synthesized zinc hydroxide‐nitrate nanocrystals (ZnHN; solubility 30–50 mg Zn L^?1) applied on to the adaxial surface of tomato leaves (Solanum lycopersicum L. cv. Roma). The total Zn absorption from ZnHN suspension positively increased with ZnHN application rates, but the relative efficacy started to decline at > 400 mg Zn L^?1. Within the 3 weeks, total Zn recovery in the ZnHN‐treated plants was 16% of the total ZnHN‐Zn applied, compared to the near 90% total Zn recovery in the Zn(NO₃)₂‐plants at the same Zn rate. Foliar‐absorbed ZnHN‐Zn was distributed from the treated leaves into other plant parts and preferentially translocated into the roots. Distribution of Zn from ZnHN‐treated leaves to apical parts was not limited by Zn deficiency. These results demonstrate that ZnHN crystals with controlled solubility provided some sort of slow‐release Zn over a certain growth period at a rate slower (but quantitatively effective) than the soluble Zn(NO₃)₂. The efficacy of the prolonged foliar Zn supply could be enhanced if the ZnHN suspension is sprayed over a large leaf surface area at the peak vegetative or early flowering stage.     

Evaluation of the GrazeIn model of grass dry‐matter intake and milk production prediction for dairy cows in temperate grass‐based production systems. 2 – Animal characteristics

This study evaluated the prediction accuracy of grass dry‐matter intake (GDMI) and milk yield predicted by the GrazeIn model using a large database representing 8787 per cow GDMI measurements. In this study, the animal input variables (age, parity, week of lactation, potential peak milk yield, milk fat content, milk protein content, bodyweight, body condition score (BCS), week of conception, BCS at calving and calf birth weight) were investigated. The mean actual GDMI of the database was 15·9 kg DM per cow d^?1 and GrazeIn predicted a mean GDMI for the database of 15·5 kg DM per cow d^?1. The mean bias was ?0·4 kg DM per cow d^?1. GrazeIn predicted GDMI for the total database with an RPE of 15·5% at cow level. The mean actual daily milk yield of the database was 21·3 kg per cow d^?1 and GrazeIn predicted a daily milk yield for the database of 22·2 kg per cow d^?1. The mean bias was +0·9 kg per cow d^?1. GrazeIn predicted milk yield for the total database with an RPE of 16·7% at cow level. From the evaluation, GrazeIn predicted milk yield of all cows in late lactation with a larger level of error than in early and mid‐lactation. This error appears to be due to the persistency of the lactation curve used by the model, which results in a higher predicted milk yield in late lactation compared with the actual milk yield.     

Effects of two different dietary sources of long chain omega-3, highly unsaturated fatty acids on incorporation into the plasma, red blood cell, and skeletal muscle in horses

The objective of this study was to examine the effects of different sources of dietary omega-3 (n-3) fatty acid supplementation on plasma, red blood cell, and skeletal muscle fatty acid compositions in horses. Twenty-one mares were blocked by age, BW, and BCS and assigned to 1 of 3 dietary treatments with 7 mares per treatment. Dietary treatments were: 1) control or no fatty acid supplement (CON), 2) 38 g of n-3 long chain, highly unsaturated fatty acid (LCHUFA) supplement/d provided by algae and fish oil (MARINE) containing alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and docosapentaenoic acid (DPA), and 3) 38 g of n-3 LCHUFA supplement/d provided by a flaxseed meal (FLAX) containing ALA. Each supplement was added to a basal diet consisting of hay and barley and was fed for 90 d. Blood samples and muscle middle gluteal biopsies were taken at d 0, 30, 60 and 90 of supplementation. Plasma, red blood cell and skeletal muscle fatty acid profiles were determined via gas chromatography. Plasma linoleic acid (LA) and ALA were at least 10 and 60% less (P < 0.01), respectively, in the MARINE compared with the FLAX and CON groups. Plasma EPA and DHA were only detected in the MARINE group, and EPA increased 40% (P < 0.001) from d 30 to 60, and DHA 19% (P < 0.01) from d 30 to 90. Red blood cell LA and ALA were not different among treatments. Red blood cell EPA and DHA were only detected in the MARINE group, where EPA increased 38% (P < 0.01) from d 30 to 60, and DHA increased 56% (P < 0.001) between d 30 and 90. Skeletal muscle LA was at least 17% less (P < 0.001) in the MARINE group compared with the other treatments. Skeletal muscle ALA was 15% less (P = 0.03) in the MARINE group compared with FLAX and CON groups. Skeletal muscle EPA was at least 25% greater (P < 0.001) in MARINE group compared with other treatments and increased (P < 0.001) by 71% from d 30 to 60. Skeletal muscle DHA was at least 57% greater (P < 0.001) in the MARINE group compared with other groups and increased (P < 0.001) by 40% between d 30 and 90. As far as the authors are aware, this is the first study to demonstrate that dietary fatty acid supplementation will affect muscle fatty acid composition in horses. Incorporation of n-3 LCHUFA into blood and muscle depends directly on dietary supply of specific fatty acids.     

High level methoprene resistance in the mosquito Ochlerotatus nigromaculis (Ludlow) in central California

In the summer of 1998, failures of methoprene field applications to control the mosquito Ochlerotatus nigromaculis (Ludlow) were noticed in several pastures in the outskirts of Fresno, California, USA. Effective control with methoprene had been achieved for over 20 years prior to this discovery. Susceptibility tests indicated that the Fresno Oc nigromaculis populations had developed several thousand‐fold higher LC₅₀ and LC₉₀ tolerance levels to methoprene compared with methoprene‐naïve populations. The synergists piperonyl butoxide (PBO), S,S,S‐tributyl phosphorotrithioate and 3‐octylthio‐1,1,1‐trifluoro‐2‐propanone had little synergistic effect, suggesting that the mechanism of methoprene tolerance was not mediated by P450 monooxygenase or carboxylesterase enzyme degradation. As part of initiating a resistance management strategy, partial reversion back to methoprene susceptibility was achieved in a resistant population after six consecutive applications of Bacillus thuringiensis israelensis Goldberg & Marga coupled with two oil and two pyrethrum + PBO applications. © 2002 Society of Chemical Industry     

Mammary cancer in the dog: a study of 120 cases.

Of the 120 cases of mammary cancer occurring in 117 female dogs (15 spayed), 2 male dogs, and 1 dog of undetermined sex, 107 (nearly 90%) were observed in dogs 8 to 15 years old. Mammary tumors occurred in nearly 14% of 875 female dogs with neoplasms. Nearly 60% of 128 neoplasms were located in the 4th and 5th mammary glands. Of the 128 cancers in these 120 dogs, 85 were classified as duct carcinoma, 38 as lobular carcinoma, 3 as malignant mixed tumor, and 2 as duct and lobular carcinomas. Most duct carcinomas originated in the epithelial cells of ducts at all levels, and a few arose in previously benign duct papillomas. The lobular carcinomas arose in alveoli and developed into progressively larger lobules. A negative factor in the development of mammary cancer is ovariectomy before or shortly after the first estrous cycle in the dog and before the age of 40 in women. In both dog and man, aging is a positive factor in the development of mammary cancer. In women, other positive factors are nulliparity and inheritance; e.g., a high rate of breast cancer in close female relatives of Jewish extraction. An epidemiologic study of breast cancer in man and dog in high-risk countries(e.g., United States) and low-risk countries (e.g., Japan) is indicated.