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There is a strong innate immunity in calves to infection with Babesia bovis. Interleukin (IL)-12 and IL-10 have been shown in vitro to be important immunoregulatory cytokines. Here we demonstrate in vivo that the protective innate response in young calves to infection with virulent B. bovis involves the early appearance of IL-12 and interferon-gamma (IFN-gamma) transcripts in the spleen. In contrast, IL-12 and IFN-gamma mRNA expression in the spleens of adult cattle that succumbed to the infection was delayed and depressed and occurred within the context of IL-10 expression. Also in contrast with calves, there was no detectable antibody response before death in adults. A vigorous CD8+ T-cell expansion occurred in the spleens of both calves and adults.

SUMMARY Young calves possess a strong innate immunity against Babesia bovis infection that lasts for approximately 6 months after birth and is abrogated with the removal of the spleen. This immunity is characterized as cellular involving a soluble mediator. Nitric oxide has been implicated by virtue of its babesiacidal affects in vitro, but questioned to be as effective in vivo, due to its ability to downregulate type-1 immunity. Spleen cells were obtained from 4-month-old calves and adult steers and processed for monitoring cytokine and inducible nitric oxide synthase (iNOS) mRNA expression during the response to initial B. bovis infection. The data provided evidence of a transient role for nitric oxide in innate immunity, characterized by brief iNOS induction in the spleen of calves that was not detectable in the spleens of adults. The iNOS message followed the early induction of interleukin (IL)-12 and interferon (IFN)-g message in calves. The induction of IL12 and IFN-g message in adults was delayed until IL-10 message was induced. Transformation growth factor-b mRNA expression levels were greater in spleen cells from adults early in infection and then declined, whereas expression levels increased in spleen cells from calves later in the infection process. Together, the data support the concept of ‘first come, first serve’ cytokine influence over cellular activities, the importance of a type-1 response in the control of an initial infection and the need for tight regulation in order to prevent pathology associated with over production of nitric oxide and inflammatory cytokines.

IL-10 has been shown to have profound immunoregulatory attributes and in the bovine appears to downregulate both Th1- and Th2-like responses. Using RT-PCR, we demonstrate IL-10 in vitro down-regulation of mRNA expression of iNOS, the cytokines involved in nitric oxide signal transduction initiation (IFN-gamma and TNF-alpha), and other mononuclear phagocyte associate cytokines. In addition, using RT-PCR with peripheral blood leukocytes and spleen leukocytes, the Griess reaction, and a killing assay, we provide evidence for the importance of iNOS in a successful immune response to B. bovis infection and for high and persistent IL-10 mRNA expression when the immune response is unsuccessful. We also provide evidence that antibody developed early after an initial infection appears to lack protective attributes (neutralizing and opsonic). Together, the data suggests that IL-10 and IFN-gamma are critical molecules involved in the response to this intraerythrocytic protozoan infection.

Growth rate of irrigated grain sorghum with moisture not limiting was measured in the field between August 11 and September 4, 1965, near Amarillo, Texas. A growth sensor was used which converted the extension of a grain sorghum leaf from the whorl, or of a head from the boot, into an electrical signal which was continuously recorded on a strip chart recorder.The minimum growth rate occurred between 7:00 and 9:00 AM on individual days. The growth rate increased rapidly after that and reached a maximum value for the day near noon. The growth rate decreased sharply during a 3- or 4-hr period which began on different days between 4:00 and 7:30 PM and lasted until 8:00 to 10:00 PM. After this evening period of sharp growth rate decline, the growth rate decreased more gradually and paralleled the air temperature decline until the morning growth minimum was reached. (Times stated are Central Standard Time, or true solar time + 50 min.) There was evidence of a double peak in the growth rate curve in the afternoon of a clear day and of a temporary acceleration of growth rate in the early morning when moisture condensed on the foliage.

Attachment and design of two types of growth sensors for obtaining a continuous record of circumference change of sugarbeet () roots are described.