hornfly development. Manure from the -FIELD Rrnett cows had the highest number 01 West -17 Bull8 (medicated) immature-stage flies while manure from Goldstein _____47 Cons (control) HORNFLY POPULATION COUNTS ON Arnett 20 Cons the North and Indian herds showed much ______(control) TEST PLOT ANIMALS FROM JUNE 28 North - 69 Cows (medicated) less hornfly development throughout. TO OCTOBER 18 On March 1 and 2, 1966, the backs of Indian 39 Dry Cows (medicated) 55% of the treated COWS from the North field, and 4'8% of the cows from the Gold- stein control field, were examined for grubs. In the treated group, four head had 1400 one grub each and one head had two grubs for an average of 0.18 grub per lPo0 head. The head counted in the control 23 looo group had a total of only 40 grubs or an average of 1.7 grubs per head (range, 0 Roo to 4). Ronnel is not yet recommended by 600 University of California for systemic con- trol of hornflies or grubs on range cattle. 400

R. F. Miller Jr. is Farm Advisor, Tu- zoo lare County; and E. C. Loomis is Exten- sion Parasitologist, University of Califor- 0 nia, Davis. 6/28 1 5 7/12 7/19 7/26 8/2 8/9 8/16 8/23 8/30 9/7 9/13 9/20 9/27 10/4 10/11 10/18

ORGANIC ACID SYNTHESIS IN LEMON FRUITS

E. BOGIN A. WALLACE

UALITY OF LEMONS and of other Major problem a net synthesis of organic acids in cells. Q citrus fruits is affected by the con- One of the major problems in the These particular results demonstrated centrations of acids in the fruit juice. For studies involved isolation of the enzyme that the organic acids could be synthe- this reason information concerning thc systems from the highly acid citrus fruits. sized in fruits. synthesis and accumulation of the acids is This was accomplished by the proper use Many biochemical mechanisms have important and has been the subject of of buffers and special grinding tech- been explored by the use of mutants, intensive studies. Until recently organic niques. Mitochondria, which have the particularly mutants of microorganisms, acids were thought to be synthesized in ability to oxidize all the tricarboxylic and this approach was applied to the leaves and then later translocated to the acid cycle intermediates, were prepared study of acid synthesis in lemon fruits. fruit. Sufficient biochemical systems have from lemon fruits. Soluble enzymes which Comparative studies were made with now been isolated from fruits to warrant have the capacity to fix carbon dioxide Eureka lemon and Tunisian swcet lemon the conclusion that lemon and other citrus into organic acids were also isolated from fruits (see table). The latter is generally fruits are quite capable of the acid syn- the fruit. Fixation of carbon dioxide is considered to be a mutant of a sour thesis. one of two mechanisms that can result in lemon. In the mutant, some biochemical

10 CALIFORNIA AGRICULTURE, AUGUST, 1966 mechanism which regulates acid accumu- DIFFERENCES IN SOUR AND SWEET LEMON FRUITS lation has obviously been lost. By com- Characteristics Sour Lemon Sweet Lemon paring biochemical reactions in the regu- Organic acid content, Oh of fresh weight 5-9 less than 1 PH 2.5-3.0 5.0-5.5 lar lemon with those in the mutant, we Amino acids, mglml iuice 0.5 1.5 hope to learn how acid synthesis is Oxygen uptake by intact vesicles, pI O?/hr/gram fresh weight 191 282 achieved in the regular lemon. Oxygen uptake by mitochondria with succinate, pl O?/hr/mg protein nitrogen 230 318 Organic acids CO? fixation with radioactive ~140~ by phosphoenolpyruvic acid carboxylose, The total amount of organic acids in cpmlmg protein nitrogen 36660 66230 sour lemon juice is far greater than that by isocitric dehydrogenase, cpm per aliquot 4770 1620 Am'nation of pyruvate low high in the sweet lemon. In contrast, the amino Main amino acid asportate olanine acid level in juice from sweet lemon is Catolase activity low high about three times as high as in the sour Citramalate oroduction hish low lemon. This could be an important factor, not only in determining the acid content malic acid content and the amount of car- better control thc factors influencing or- of the juice but also in determining the bon dioxide fixation decrease with age of ganic acid contents of the fruits. pH of the juice. The pH of sweet lemon fruit on both the fresh and dry weight juice is much higher than that of sour bases. The sour lemon, which has the high E. Bogin is Postgraduate Research lemon (see table) When the juice of both Fellow and Wallace is Professor of . acid content, had a higher capacity for A. fruits was passed over a cation exchange Plant Nutrition, Department of Agricul- carbon dioxide fixation than the sweet resin to remove the amino acids, the re- lemon, which has the low acid content. tural Sciences, University of California, sulting pH of the filtrate from both fruits Distribution of activity among different Los Angeles. was very nearly the same-sour lemon carbon dioxide fixing mechanisms, how- being 0.5 unit lower than the sweet ever. is vastlv different for the two fruitq lemon. and one of the mechanisms may he the Sweet lemon regulating factor. NEW PUBLICATIONS A metabolic inhibitor, citramalate, was ready for distribution The sweet lemon, which is low in acids, found to be synthesized in much greater a greater oxygen uptake (respiration Single copies of these publications-except Manuals had quantities in preparations from sour than and books-or a catalog of Agricultural Publications rate) than the sour lemon. An analogy is may be obtained without charge from the local ofice in those from sweet lemon. This com- of a known with iron-deficient plant leaves the Farm Advisor or by addresslng request to: pound is sufficiently similar to citric acid Agricultural Publications, 207 University Hall, Univer- where organic acids are increased and sity of California, Berkeley, California 94720. When that it is a competitive inhibitor with ordering sale items, please enclose payment. Make oxypcn uptake is decreased (relative to citrate for the enzyme aconitase. This is checks or money orders payable to The Regents of the green leaves). This provides a clue as to University of California. a promising hypothesis to explain why how the organic acid build-up is regu- citric acid accumulates in great quantities MUSKMELON PRODUCTION IN CALIFORNIA. lated, and the resulting hypothesis is be- in the sour lemon. Cir. 536. Supplies information on the ing studied. varieties adapted to Calilornia, and dis- Intact fruit vesicles and biochemically Cell storage cusses all cultural operations, diseases, actile preparations from the vesicles When organic acids accumulate in the insect pests, harvesting, and packing and readily fix carbon dioxide. There are fruits, they are stored in a cellular com- shipping. several mechanisms by which this occurs, partment called the vacuole. membrane and one or more are of major importance A WOOD RESIDUE USES IN THE CALIFORNIA separates the vacuole from the protoplasm in the net synthesis of organic acids. Both PINE REGION. Bul. 817. AS timber supplies of the cell. This membrane is extremely become less available and competition efficient because it must maintain a gradi- with other materials bccomes more in- ent of about 10,000 times for the hydro- tense, alternate uses for wood residues CALIFORNIA AGRICULTURE gen ion concentration between the two will become a more important and neces- Progress Reports of Agricultural Research, published monthly by the University of Cali- sides in sour lemon. Just how the cell can sary part of the forest products industry. fornia Division of A~ricnltnralSciences. do this is also being studied. Bulletin 817 explores and evaluates the William W. Paul ...... Vanuger Even though acids are most likely syn- possibilities of several alternative appli- Agricultural Publications Jerry Lester ...... Editor thesized within the fruits, leaves do have cations. Chispa Olsen ...... Assistant Editor a great effect in regulating thc content. California Agriculture This observation was made by varying A TECHNICAL STUDY OF INSECTS AFFECT- Articles published herein may be republished ING THE SYCAMORE TREE IN SOUTHERN or reprinted provided no advertisement for a the number of leaves in proximity to a coiniiiercial prodnct is implied or imprinted. fruit by girdling the branches leading to CALIFORNIA. Bd. 818. Includes identifica- Please credit: University of California tion of, and insecticide dosages for con- Division of Agricultural Sciences. a fruit. Whether thr determining factor Cdifornia Agriculture will be sent free upon trol of, sycamore pests. Amply illustrated. request addressed to: Editor, California is the supply of photosynthate or of a Agriculture, 207 University Hall, 2200 Uni- versity Avenue, Berkeley, California 94720. regulator of some kind is not yet known. SOCIAL DOMINANCE IN RANGE COWS AND To simplify the information in California The acid content of lemon and other ITS EFFECT ON SUPPLEMENTAL FEEDING. Agriculture it is sonietimos necessary to use trade names of product6 or equipment. No citrus fruits is influenced by climate, root- Bul. 819. Reports studies of variation in endorsement of named products is intended nor is criticism implied of similar products stock, several different plant nutrients, social dominance among different agc which are not montioned. and variety. These factors are of consider- classes of cows-and the problems en- 111 able importance in determining fruit countered when a mixed-age herd is sup- quality. Continued studies may help to plemented on the range.

CALIFORNIA AGRICULTURE, AUGUST, 1966 11